We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
Refined parameters of the HD 22946 planetary system and the true orbital peri...Sérgio Sacani
Multi-planet systems are important sources of information regarding the evolution of planets. However, the long-period
planets in these systems often escape detection. These objects in particular may retain more of their primordial characteristics compared
to close-in counterparts because of their increased distance from the host star. HD 22946 is a bright (G = 8.13 mag) late F-type star
around which three transiting planets were identified via Transiting Exoplanet Survey Satellite (TESS) photometry, but the true orbital
period of the outermost planet d was unknown until now.
Aims. We aim to use the Characterising Exoplanet Satellite (CHEOPS) space telescope to uncover the true orbital period of HD 22946d
and to refine the orbital and planetary properties of the system, especially the radii of the planets.
Methods. We used the available TESS photometry of HD 22946 and observed several transits of the planets b, c, and d using CHEOPS.
We identified two transits of planet d in the TESS photometry, calculated the most probable period aliases based on these data, and
then scheduled CHEOPS observations. The photometric data were supplemented with ESPRESSO (Echelle SPectrograph for Rocky
Exoplanets and Stable Spectroscopic Observations) radial velocity data. Finally, a combined model was fitted to the entire dataset in
order to obtain final planetary and system parameters.
Results. Based on the combined TESS and CHEOPS observations, we successfully determined the true orbital period of the planet d
to be 47.42489 ± 0.00011 days, and derived precise radii of the planets in the system, namely 1.362 ± 0.040 R⊕, 2.328 ± 0.039 R⊕, and
2.607 ± 0.060 R⊕ for planets b, c, and d, respectively. Due to the low number of radial velocities, we were only able to determine 3σ
upper limits for these respective planet masses, which are 13.71 M⊕, 9.72 M⊕, and 26.57 M⊕. We estimated that another 48 ESPRESSO
radial velocities are needed to measure the predicted masses of all planets in HD 22946. We also derived stellar parameters for the host
star.
Conclusions. Planet c around HD 22946 appears to be a promising target for future atmospheric characterisation via transmission
spectroscopy. We can also conclude that planet d, as a warm sub-Neptune, is very interesting because there are only a few similar
confirmed exoplanets to date. Such objects are worth investigating in the near future, for example in terms of their composition and
internal structure.
Two warm Neptunes transiting HIP 9618 revealed by TESS and CheopsSérgio Sacani
This document summarizes the discovery of two warm Neptunes transiting the bright star HIP 9618, as revealed by TESS and CHEOPS observations. TESS observed two transits of one planet (HIP 9618 b), separated by an 11.8 day gap, and one transit of a second planet (HIP 9618 c). Follow-up photometry and reanalysis of the TESS data determined the true period of HIP 9618 b to be 20.77291 days. CHEOPS then performed targeted photometry to determine the true 52.56349 day period of HIP 9618 c. High-resolution spectroscopy found HIP 9618 b has a mass of 10.0 ± 3.
TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf ...Sérgio Sacani
We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461,
TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing
two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet,
HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up
observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the
radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has
a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93+0.07 −0.06 R⊕ and a period
of 21.583298+0.000052
−0.000055 d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanetsystems with two warm ( 700 K)sub-Neptune sized planetstransiting a brightstar (G ≤ 10 mag). It is an excellent target for detailed
characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
LHS 475 b: A Venus-sized Planet Orbiting a Nearby M DwarfSérgio Sacani
Based on photometric observations by TESS, we present the discovery of a Venussized planet transiting LHS 475, an M3 dwarf located 12.5 pc from the Sun. The mass
of the star is 0.274 ± 0.015 M. The planet, originally reported as TOI 910.01, has an
orbital period of 2.0291025 ± 0.0000020 days and an estimated radius of 0.955 ± 0.053
R⊕. We confirm the validity and source of the transit signal with MEarth ground-based
follow-up photometry of five individual transits. We present radial velocity data from
CHIRON that rule out massive companions. In accordance with the observed massradius distribution of exoplanets as well as planet formation theory, we expect this
Venus-sized companion to be terrestrial, with an estimated RV semi-amplitude close to
1.0 m/s. LHS 475 b is likely too hot to be habitable but is a suitable candidate for
emission and transmission spectroscopy.
HD 20329b: An ultra-short-period planet around a solar-type star found by TESSSérgio Sacani
This document summarizes the discovery and characterization of HD 20329b, an ultra-short period planet orbiting a solar-type star. Key findings include:
1) HD 20329b was discovered using transit data from the TESS space telescope. It has an orbital period of 0.9261 days.
2) Follow-up observations with HARPS-N measured the planet's mass as 7.42 Earth masses. Its radius is 1.72 Earth radii, giving it a density of 8.06 g/cm3.
3) HD 20329b joins the roughly 30 known ultra-short period planets (orbital period <1 day) that have both mass and radius measurements, helping
The kepler 10_planetary_system_revisited_by_harpsSérgio Sacani
This document discusses observations of the Kepler-10 planetary system made with the HARPS-N spectrograph. The observations resulted in improved precision for the masses of Kepler-10b and Kepler-10c. Kepler-10b's mass was determined to be 3.33 ± 0.49 Earth masses, confirming its rocky composition. Kepler-10c's mass of 17.2 ± 1.9 Earth masses makes it the first strong evidence of a class of more massive solid Neptune-sized planets with longer orbital periods. The improved mass measurements will help constrain models of the internal structure and composition of these planets.
Refined parameters of the HD 22946 planetary system and the true orbital peri...Sérgio Sacani
Multi-planet systems are important sources of information regarding the evolution of planets. However, the long-period
planets in these systems often escape detection. These objects in particular may retain more of their primordial characteristics compared
to close-in counterparts because of their increased distance from the host star. HD 22946 is a bright (G = 8.13 mag) late F-type star
around which three transiting planets were identified via Transiting Exoplanet Survey Satellite (TESS) photometry, but the true orbital
period of the outermost planet d was unknown until now.
Aims. We aim to use the Characterising Exoplanet Satellite (CHEOPS) space telescope to uncover the true orbital period of HD 22946d
and to refine the orbital and planetary properties of the system, especially the radii of the planets.
Methods. We used the available TESS photometry of HD 22946 and observed several transits of the planets b, c, and d using CHEOPS.
We identified two transits of planet d in the TESS photometry, calculated the most probable period aliases based on these data, and
then scheduled CHEOPS observations. The photometric data were supplemented with ESPRESSO (Echelle SPectrograph for Rocky
Exoplanets and Stable Spectroscopic Observations) radial velocity data. Finally, a combined model was fitted to the entire dataset in
order to obtain final planetary and system parameters.
Results. Based on the combined TESS and CHEOPS observations, we successfully determined the true orbital period of the planet d
to be 47.42489 ± 0.00011 days, and derived precise radii of the planets in the system, namely 1.362 ± 0.040 R⊕, 2.328 ± 0.039 R⊕, and
2.607 ± 0.060 R⊕ for planets b, c, and d, respectively. Due to the low number of radial velocities, we were only able to determine 3σ
upper limits for these respective planet masses, which are 13.71 M⊕, 9.72 M⊕, and 26.57 M⊕. We estimated that another 48 ESPRESSO
radial velocities are needed to measure the predicted masses of all planets in HD 22946. We also derived stellar parameters for the host
star.
Conclusions. Planet c around HD 22946 appears to be a promising target for future atmospheric characterisation via transmission
spectroscopy. We can also conclude that planet d, as a warm sub-Neptune, is very interesting because there are only a few similar
confirmed exoplanets to date. Such objects are worth investigating in the near future, for example in terms of their composition and
internal structure.
Two warm Neptunes transiting HIP 9618 revealed by TESS and CheopsSérgio Sacani
This document summarizes the discovery of two warm Neptunes transiting the bright star HIP 9618, as revealed by TESS and CHEOPS observations. TESS observed two transits of one planet (HIP 9618 b), separated by an 11.8 day gap, and one transit of a second planet (HIP 9618 c). Follow-up photometry and reanalysis of the TESS data determined the true period of HIP 9618 b to be 20.77291 days. CHEOPS then performed targeted photometry to determine the true 52.56349 day period of HIP 9618 c. High-resolution spectroscopy found HIP 9618 b has a mass of 10.0 ± 3.
TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf ...Sérgio Sacani
We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461,
TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing
two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet,
HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up
observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the
radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has
a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93+0.07 −0.06 R⊕ and a period
of 21.583298+0.000052
−0.000055 d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanetsystems with two warm ( 700 K)sub-Neptune sized planetstransiting a brightstar (G ≤ 10 mag). It is an excellent target for detailed
characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
LHS 475 b: A Venus-sized Planet Orbiting a Nearby M DwarfSérgio Sacani
Based on photometric observations by TESS, we present the discovery of a Venussized planet transiting LHS 475, an M3 dwarf located 12.5 pc from the Sun. The mass
of the star is 0.274 ± 0.015 M. The planet, originally reported as TOI 910.01, has an
orbital period of 2.0291025 ± 0.0000020 days and an estimated radius of 0.955 ± 0.053
R⊕. We confirm the validity and source of the transit signal with MEarth ground-based
follow-up photometry of five individual transits. We present radial velocity data from
CHIRON that rule out massive companions. In accordance with the observed massradius distribution of exoplanets as well as planet formation theory, we expect this
Venus-sized companion to be terrestrial, with an estimated RV semi-amplitude close to
1.0 m/s. LHS 475 b is likely too hot to be habitable but is a suitable candidate for
emission and transmission spectroscopy.
HD 20329b: An ultra-short-period planet around a solar-type star found by TESSSérgio Sacani
This document summarizes the discovery and characterization of HD 20329b, an ultra-short period planet orbiting a solar-type star. Key findings include:
1) HD 20329b was discovered using transit data from the TESS space telescope. It has an orbital period of 0.9261 days.
2) Follow-up observations with HARPS-N measured the planet's mass as 7.42 Earth masses. Its radius is 1.72 Earth radii, giving it a density of 8.06 g/cm3.
3) HD 20329b joins the roughly 30 known ultra-short period planets (orbital period <1 day) that have both mass and radius measurements, helping
The kepler 10_planetary_system_revisited_by_harpsSérgio Sacani
This document discusses observations of the Kepler-10 planetary system made with the HARPS-N spectrograph. The observations resulted in improved precision for the masses of Kepler-10b and Kepler-10c. Kepler-10b's mass was determined to be 3.33 ± 0.49 Earth masses, confirming its rocky composition. Kepler-10c's mass of 17.2 ± 1.9 Earth masses makes it the first strong evidence of a class of more massive solid Neptune-sized planets with longer orbital periods. The improved mass measurements will help constrain models of the internal structure and composition of these planets.
Two super-Earths at the edge of the habitable zone of the nearby M dwarf TOI-...Sérgio Sacani
The main scientific goal of TESS is to find planets smaller than Neptune around stars bright enough to allow further characterization studies. Given
our current instrumentation and detection biases, M dwarfs are prime targets to search for small planets that are in (or nearby) the habitable zone
of their host star. Here we use photometric observations and CARMENES radial velocity measurements to validate a pair of transiting planet
candidates found by TESS. The data was fitted simultaneously using a Bayesian MCMC procedure taking into account the stellar variability
present in the photometric and spectroscopic time series. We confirm the planetary origin of the two transiting candidates orbiting around TOI-
2095 (TIC 235678745). The star is a nearby M dwarf (d = 41:90 0:03 pc, Te = 3759 87 K, V = 12:6 mag) with a stellar mass and radius
of M? = 0:44 0:02 M and R? = 0:44 0:02 R, respectively. The planetary system is composed of two transiting planets: TOI-2095b with an
orbital period of Pb = 17:66484 (7 105) days and TOI-2095c with Pc = 28:17232 (14 105) days. Both planets have similar sizes with
Rb = 1:250:07 R and Rc = 1:330:08 R for planet b and c, respectively.We put upper limits on the masses of these objects with Mb < 4:1 M
for the inner and Mc < 7:4 M for the outer planet (95% confidence level). These two planets present equilibrium temperatures in the range of 300
- 350 K and are close to the inner edge of the habitable zone of their star.
TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS...Sérgio Sacani
A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few
dozen of these planets have a precise radius measurement. Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and, more importantly, for shedding light on the formation and evolution
of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are
unaltered by intense stellar irradiation and tidal effects.
Aims. We aim to identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as single or duo-transit events.
Our goal is to solve the orbital periods of TESS duo-transit candidates with the use of additional space-based photometric observations
and to collect follow-up spectroscopic observations in order to confirm the planetary nature and measure the mass of the candidates.
Methods. We use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. Once a period is confirmed, we jointly model the TESS and CHEOPS light curves
along with the radial velocity datasets to measure the orbital parameters of the system and obtain precise mass and radius measurements.
Results. We report the discovery of a long-period transiting Neptune-mass planet orbiting the G7-type star TOI-5678. Our spectroscopic analysis shows that TOI-5678 is a star with a solar metallicity. The TESS light curve of TOI-5678 presents two transit events
separated by almost two years. In addition, CHEOPS observed the target as part of its Guaranteed Time Observation program. After
four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Follow-up
radial velocity observations were carried out with the ground-based high-resolution spectrographs CORALIE and HARPS. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet, and we measure an orbital eccentricity consistent with zero at 2σ. The
planet TOI-5678 b has a mass of 20 ± 4 Earth masses (M⊕) and a radius of 4.91 ± 0.08 R⊕. Using interior structure modeling, we find
that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2
+1.7
−1.3 M⊕.
Conclusions. TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar
insolation (11 S ⊕). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars
are suitable targets to study the atmospheric composition of cooler gas giants.
Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Three Ultra-...Sérgio Sacani
We present deep Hubble Space Telescope (HST) imaging of five faint dwarf galaxies associated with the nearby
spiral NGC 253 (D ≈ 3.5 Mpc). Three of these are newly discovered dwarf galaxies, while all five were found in
the Panoramic Imaging Survey of Centaurus and Sculptor, a Magellan+Megacam survey to identify faint dwarfs
and other substructures in resolved stellar light around massive galaxies outside of the Local Group. Our HST data
reach 3 magnitudes below the tip of the red giant branch for each dwarf, allowing us to derive their distances,
structural parameters, and luminosities. All five systems contain mostly old, metal-poor stellar populations
(age ∼12 Gyr, [M/H] −1.5) and have sizes (rh ∼ 110–3000 pc) and luminosities (MV ∼ −7 to −12 mag) largely
consistent with Local Group dwarfs. The three new NGC 253 satellites are among the faintest systems discovered
beyond the Local Group. We also use archival H I data to place limits on the gas content of our discoveries. Deep
imaging surveys such as our program around NGC 253 promise to elucidate the faint end of the satellite luminosity
function and its scatter across a range of galaxy masses, morphologies, and environments in the decade to come
This summarizes a scientific study on long-distance quantum teleportation between two laboratories separated by 55 meters but connected by 2 kilometers of fiber optic cable. The key points are:
1) Researchers teleported quantum states (qubits) carried by photons at 1.3 micrometer wavelengths onto photons at 1.55 micrometer wavelengths between the two laboratories.
2) The qubits were encoded in time-bin superpositions and entanglement rather than polarization to make them more robust against decoherence in optical fibers.
3) A partial Bell state measurement was performed using linear optics at the receiving end to probabilistically teleport the quantum states over the long distance.
A super earth_sized_planet_orbiting_in_or_near_the_habitable_zone_around_sun_...Sérgio Sacani
This document summarizes the discovery of a super-Earth-sized planet orbiting in or near the habitable zone of a Sun-like star called Kepler-69. Using data from the Kepler spacecraft, astronomers detected two planets transiting Kepler-69, called Kepler-69b and Kepler-69c. Kepler-69c is estimated to have a radius of 1.7 Earth radii and orbit every 242.5 days, placing it close to the star's habitable zone where liquid water could exist on the surface. At 1.7 Earth radii, Kepler-69c represents the smallest planet found by Kepler to be potentially habitable, and is an important discovery on the path to finding the first true Earth analog.
NGTS-1b: A hot Jupiter transiting an M-dwarfSérgio Sacani
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf
host (Teff,∗=3916 +71
−63 K) in a P = 2.647 d orbit discovered as part of the Next Generation
Transit Survey (NGTS). The planet has a mass of 0.812 +0.066
−0.075MJ and radius
of 1.33 +0.61
−0.33 RJ , making it the largest and most massive planet discovered transiting
any M-dwarf. NGTS-1b is the third transiting giant planet found around an M-dwarf,
reinforcing the notion that close-in gas giants can form and migrate similar to the
known population of hot Jupiters around solar type stars. The host star shows no
signs of activity, and the kinematics hint at the star being from the thick disk population.
With a deep (2.5%) transit around a K = 11.9 host, NGTS-1b will be a strong
candidate to probe giant planet composition around M-dwarfs via JWST transmission
spectroscopy.
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2Sérgio Sacani
This document reports the discovery of three transiting super-Earth planets orbiting a nearby bright M0 dwarf star, EPIC 201367065, using data from the K2 mission. Photometry from K2 reveals three planetary candidates with orbital periods of 10.056, 24.641, and ~45 days and radii between 1.5-2.1 Earth radii. Spectroscopy of the host star determines it has a mass of 0.601 solar masses, radius of 0.561 solar radii, and is located about 45 parsecs away, making the planets some of the coolest small planets known around a nearby star. The system presents an opportunity to measure the planet masses and constrain atmospheric compositions via future observations
We present the 2020 version of the Siena Galaxy Atlas (SGA-2020), a multiwavelength optical and infrared
imaging atlas of 383,620 nearby galaxies. The SGA-2020 uses optical grz imaging over ≈20,000 deg2 from the
Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9 and infrared imaging in
four bands (spanning 3.4–22 μm) from the 6 year unWISE coadds; it is more than 95% complete for galaxies larger
than R(26) ≈ 25″ and r < 18 measured at the 26 mag arcsec−2 isophote in the r band. The atlas delivers precise
coordinates, multiwavelength mosaics, azimuthally averaged optical surface-brightness profiles, model images and
photometry, and additional ancillary metadata for the full sample. Coupled with existing and forthcoming optical
spectroscopy from the DESI, the SGA-2020 will facilitate new detailed studies of the star formation and mass
assembly histories of nearby galaxies; enable precise measurements of the local velocity field via the Tully–Fisher
and fundamental plane relations; serve as a reference sample of lasting legacy value for time-domain and
multimessenger astronomical events; and more.
Validation of twelve_small_kepler_transiting_planets_in_the_habitable_zoneSérgio Sacani
Artigo descreve a análise dos mais novos exoplanetas descobertos pela missão Kepler, incluindo o Kepler-438b, o exoplaneta mais parecido com a Terra já descoberto até o momento.
The harps n-rocky_planet_search_hd219134b_transiting_rocky_planetSérgio Sacani
Usando o espectrógrafo HARPS-N acoplado ao Telescopio Nazionale Galileo no Observatório de Roque de Los Muchachos, nas Ilhas Canárias, os astrônomos descobriram três exoplanetas, classificados como Super-Terras e um gigante gasoso orbitando uma estrela próxima, chamada de HD 219134.
A HD 219134, também conhecida como HR 8832 é uma estrela do tipo anã-K de quinta magnitude, localizada a aproximadamente 21 anos-luz de distância da Terra, na constelação de Cassiopeia.
A estrela é levemente mais fria e menos massiva que o nosso sol. Ela é tão brilhante que pode ser observada a olho nu.
O sistema planetário HD 219134, abriga um planeta gigante gasoso externo e três planetas internos classificados como super-Terras, um dos quais transita em frente à estrela.
The Sparkler: Evolved High-redshift Globular Cluster Candidates Captured by JWSTSérgio Sacani
This document discusses compact red sources detected around a strongly lensed galaxy ("the Sparkler") at a redshift of 1.378 using JWST data. Photometry and morphological fits of the sources suggest they are spatially unresolved, very red, and consistent with old stellar populations. Spectroscopy shows emission from the galaxy but no signs of star formation in the red sources. The sources are most likely evolved globular clusters dating back to formation redshifts between 7-11, corresponding to ages of 3.9-4.1 billion years at the time of observation. If confirmed, these would be the first observed globular clusters at high redshift, opening a window into early globular cluster formation in the first billion years of
Star formation at the smallest scales; A JWST study of the clump populations ...Sérgio Sacani
We present the clump populations detected in 18 lensed galaxies at redshifts 1 to 8.5 within the lensing cluster field SMACS0723.
The recent JWST Early Release Observations of this poorly known region of the sky have revealed numerous point-like sources
within and surrounding their host galaxies, undetected in the shallower HST images. We use JWST multiband photometry and
the lensing model of this galaxy cluster to estimate the intrinsic sizes and magnitudes of the stellar clumps. We derive optical
restframe effective radii from <10 to hundreds pc and masses ranging from ∼ 105
to 109 M, overlapping with massive star
clusters in the local universe. Clump ages range from 1 Myr to 1 Gyr. We compare the crossing time to the age of the clumps
and determine that between 45 and 60 % of the detected clumps are consistent with being gravitationally bound. On average,
the dearth of Gyr old clumps suggests that the dissolution time scales are shorter than 1 Gyr. We see a significant increase in the
luminosity (mass) surface density of the clumps with redshift. Clumps in reionisation era galaxies have stellar densities higher
than star clusters in the local universe. We zoom in into single galaxies at redshift < 6 and find for two galaxies, the Sparkler and
the Firework, that their star clusters/clumps show distinctive colour distributions and location surrounding their host galaxy that
are compatible with being accredited or formed during merger events. The ages of some of the compact clusters are between
1 and 4 Gyr, e.g., globular cluster precursors formed around 9-12 Gyr ago. Our study, conducted on a small sample of galaxies,
shows the potential of JWST observations for understanding the conditions under which star clusters form in rapidly evolving
galaxies.
TOI-4600 b and c: Two Long-period Giant Planets Orbiting an Early K DwarfSérgio Sacani
We report the discovery and validation of two long-period giant exoplanets orbiting the early K dwarf TOI-4600
(V = 12.6, T = 11.9), first detected using observations from the Transiting Exoplanet Survey Satellite (TESS) by
the TESS Single Transit Planet Candidate Working Group. The inner planet, TOI-4600 b, has a radius of
6.80 ± 0.31 R⊕ and an orbital period of 82.69 days. The outer planet, TOI-4600 c, has a radius of 9.42 ± 0.42 R⊕
and an orbital period of 482.82 days, making it the longest-period confirmed or validated planet discovered by
TESS to date. We combine TESS photometry and ground-based spectroscopy, photometry, and high-resolution
imaging to validate the two planets. With equilibrium temperatures of 347 K and 191 K, respectively, TOI-4600 b
and c add to the small but growing population of temperate giant exoplanets that bridge the gap between hot/warm
Jupiters and the solar system’s gas giants. TOI-4600 is a promising target for further transit and precise RV
observations to measure the masses and orbits of the planets as well as search for additional nontransiting planets.
Additionally, with Transit Spectroscopy Metric values of ∼30, both planets are amenable for atmospheric
characterization with JWST. Together, these will lend insight into the formation and evolution of planet systems
with multiple giant exoplanets.
Kepler-1647b is the largest and longest-period Kepler transiting circumbinary planet discovered to date. It orbits an eclipsing binary star system with an orbital period of approximately 1100 days, making it one of the longest-period transiting planets known. The planet is around 1.06 times the size of Jupiter and perturbes the times of the stellar eclipses, allowing its mass to be measured at 1.52 times that of Jupiter. Despite its long orbital period compared to Earth, the planet resides in the habitable zone of the binary star system throughout its orbit. The discovery of this unusual planetary system provides insights into theories of planet formation and dynamics in multiple star systems.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
The Exoplanet Radius Valley from Gas-driven Planet Migration and Breaking of ...Sérgio Sacani
This paper aims to test whether the exoplanet radius valley can be explained by planet formation models, particularly the gas-driven migration model. The migration model proposes that planets formed in resonant chains during the gas disk phase and most chains became unstable after gas dispersal, leading to collisions. Simulations of this model produce systems with rocky, water-rich, or mixed compositions. By combining the simulation outcomes with mass-radius relationships and assuming atmospheric loss in late impacts, the authors show the migration model can account for the observed bimodal radius distribution and uniform sizes within systems. This suggests planets around 1.4 Earth radii are rocky while those around 2.4 Earth radii contain water, challenging an exclusively rocky composition for "mini-Neptunes
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
More Related Content
Similar to Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TESS and CHEOPS
Two super-Earths at the edge of the habitable zone of the nearby M dwarf TOI-...Sérgio Sacani
The main scientific goal of TESS is to find planets smaller than Neptune around stars bright enough to allow further characterization studies. Given
our current instrumentation and detection biases, M dwarfs are prime targets to search for small planets that are in (or nearby) the habitable zone
of their host star. Here we use photometric observations and CARMENES radial velocity measurements to validate a pair of transiting planet
candidates found by TESS. The data was fitted simultaneously using a Bayesian MCMC procedure taking into account the stellar variability
present in the photometric and spectroscopic time series. We confirm the planetary origin of the two transiting candidates orbiting around TOI-
2095 (TIC 235678745). The star is a nearby M dwarf (d = 41:90 0:03 pc, Te = 3759 87 K, V = 12:6 mag) with a stellar mass and radius
of M? = 0:44 0:02 M and R? = 0:44 0:02 R, respectively. The planetary system is composed of two transiting planets: TOI-2095b with an
orbital period of Pb = 17:66484 (7 105) days and TOI-2095c with Pc = 28:17232 (14 105) days. Both planets have similar sizes with
Rb = 1:250:07 R and Rc = 1:330:08 R for planet b and c, respectively.We put upper limits on the masses of these objects with Mb < 4:1 M
for the inner and Mc < 7:4 M for the outer planet (95% confidence level). These two planets present equilibrium temperatures in the range of 300
- 350 K and are close to the inner edge of the habitable zone of their star.
TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS...Sérgio Sacani
A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few
dozen of these planets have a precise radius measurement. Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and, more importantly, for shedding light on the formation and evolution
of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are
unaltered by intense stellar irradiation and tidal effects.
Aims. We aim to identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as single or duo-transit events.
Our goal is to solve the orbital periods of TESS duo-transit candidates with the use of additional space-based photometric observations
and to collect follow-up spectroscopic observations in order to confirm the planetary nature and measure the mass of the candidates.
Methods. We use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. Once a period is confirmed, we jointly model the TESS and CHEOPS light curves
along with the radial velocity datasets to measure the orbital parameters of the system and obtain precise mass and radius measurements.
Results. We report the discovery of a long-period transiting Neptune-mass planet orbiting the G7-type star TOI-5678. Our spectroscopic analysis shows that TOI-5678 is a star with a solar metallicity. The TESS light curve of TOI-5678 presents two transit events
separated by almost two years. In addition, CHEOPS observed the target as part of its Guaranteed Time Observation program. After
four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Follow-up
radial velocity observations were carried out with the ground-based high-resolution spectrographs CORALIE and HARPS. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet, and we measure an orbital eccentricity consistent with zero at 2σ. The
planet TOI-5678 b has a mass of 20 ± 4 Earth masses (M⊕) and a radius of 4.91 ± 0.08 R⊕. Using interior structure modeling, we find
that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2
+1.7
−1.3 M⊕.
Conclusions. TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar
insolation (11 S ⊕). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars
are suitable targets to study the atmospheric composition of cooler gas giants.
Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Three Ultra-...Sérgio Sacani
We present deep Hubble Space Telescope (HST) imaging of five faint dwarf galaxies associated with the nearby
spiral NGC 253 (D ≈ 3.5 Mpc). Three of these are newly discovered dwarf galaxies, while all five were found in
the Panoramic Imaging Survey of Centaurus and Sculptor, a Magellan+Megacam survey to identify faint dwarfs
and other substructures in resolved stellar light around massive galaxies outside of the Local Group. Our HST data
reach 3 magnitudes below the tip of the red giant branch for each dwarf, allowing us to derive their distances,
structural parameters, and luminosities. All five systems contain mostly old, metal-poor stellar populations
(age ∼12 Gyr, [M/H] −1.5) and have sizes (rh ∼ 110–3000 pc) and luminosities (MV ∼ −7 to −12 mag) largely
consistent with Local Group dwarfs. The three new NGC 253 satellites are among the faintest systems discovered
beyond the Local Group. We also use archival H I data to place limits on the gas content of our discoveries. Deep
imaging surveys such as our program around NGC 253 promise to elucidate the faint end of the satellite luminosity
function and its scatter across a range of galaxy masses, morphologies, and environments in the decade to come
This summarizes a scientific study on long-distance quantum teleportation between two laboratories separated by 55 meters but connected by 2 kilometers of fiber optic cable. The key points are:
1) Researchers teleported quantum states (qubits) carried by photons at 1.3 micrometer wavelengths onto photons at 1.55 micrometer wavelengths between the two laboratories.
2) The qubits were encoded in time-bin superpositions and entanglement rather than polarization to make them more robust against decoherence in optical fibers.
3) A partial Bell state measurement was performed using linear optics at the receiving end to probabilistically teleport the quantum states over the long distance.
A super earth_sized_planet_orbiting_in_or_near_the_habitable_zone_around_sun_...Sérgio Sacani
This document summarizes the discovery of a super-Earth-sized planet orbiting in or near the habitable zone of a Sun-like star called Kepler-69. Using data from the Kepler spacecraft, astronomers detected two planets transiting Kepler-69, called Kepler-69b and Kepler-69c. Kepler-69c is estimated to have a radius of 1.7 Earth radii and orbit every 242.5 days, placing it close to the star's habitable zone where liquid water could exist on the surface. At 1.7 Earth radii, Kepler-69c represents the smallest planet found by Kepler to be potentially habitable, and is an important discovery on the path to finding the first true Earth analog.
NGTS-1b: A hot Jupiter transiting an M-dwarfSérgio Sacani
We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf
host (Teff,∗=3916 +71
−63 K) in a P = 2.647 d orbit discovered as part of the Next Generation
Transit Survey (NGTS). The planet has a mass of 0.812 +0.066
−0.075MJ and radius
of 1.33 +0.61
−0.33 RJ , making it the largest and most massive planet discovered transiting
any M-dwarf. NGTS-1b is the third transiting giant planet found around an M-dwarf,
reinforcing the notion that close-in gas giants can form and migrate similar to the
known population of hot Jupiters around solar type stars. The host star shows no
signs of activity, and the kinematics hint at the star being from the thick disk population.
With a deep (2.5%) transit around a K = 11.9 host, NGTS-1b will be a strong
candidate to probe giant planet composition around M-dwarfs via JWST transmission
spectroscopy.
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2Sérgio Sacani
This document reports the discovery of three transiting super-Earth planets orbiting a nearby bright M0 dwarf star, EPIC 201367065, using data from the K2 mission. Photometry from K2 reveals three planetary candidates with orbital periods of 10.056, 24.641, and ~45 days and radii between 1.5-2.1 Earth radii. Spectroscopy of the host star determines it has a mass of 0.601 solar masses, radius of 0.561 solar radii, and is located about 45 parsecs away, making the planets some of the coolest small planets known around a nearby star. The system presents an opportunity to measure the planet masses and constrain atmospheric compositions via future observations
We present the 2020 version of the Siena Galaxy Atlas (SGA-2020), a multiwavelength optical and infrared
imaging atlas of 383,620 nearby galaxies. The SGA-2020 uses optical grz imaging over ≈20,000 deg2 from the
Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9 and infrared imaging in
four bands (spanning 3.4–22 μm) from the 6 year unWISE coadds; it is more than 95% complete for galaxies larger
than R(26) ≈ 25″ and r < 18 measured at the 26 mag arcsec−2 isophote in the r band. The atlas delivers precise
coordinates, multiwavelength mosaics, azimuthally averaged optical surface-brightness profiles, model images and
photometry, and additional ancillary metadata for the full sample. Coupled with existing and forthcoming optical
spectroscopy from the DESI, the SGA-2020 will facilitate new detailed studies of the star formation and mass
assembly histories of nearby galaxies; enable precise measurements of the local velocity field via the Tully–Fisher
and fundamental plane relations; serve as a reference sample of lasting legacy value for time-domain and
multimessenger astronomical events; and more.
Validation of twelve_small_kepler_transiting_planets_in_the_habitable_zoneSérgio Sacani
Artigo descreve a análise dos mais novos exoplanetas descobertos pela missão Kepler, incluindo o Kepler-438b, o exoplaneta mais parecido com a Terra já descoberto até o momento.
The harps n-rocky_planet_search_hd219134b_transiting_rocky_planetSérgio Sacani
Usando o espectrógrafo HARPS-N acoplado ao Telescopio Nazionale Galileo no Observatório de Roque de Los Muchachos, nas Ilhas Canárias, os astrônomos descobriram três exoplanetas, classificados como Super-Terras e um gigante gasoso orbitando uma estrela próxima, chamada de HD 219134.
A HD 219134, também conhecida como HR 8832 é uma estrela do tipo anã-K de quinta magnitude, localizada a aproximadamente 21 anos-luz de distância da Terra, na constelação de Cassiopeia.
A estrela é levemente mais fria e menos massiva que o nosso sol. Ela é tão brilhante que pode ser observada a olho nu.
O sistema planetário HD 219134, abriga um planeta gigante gasoso externo e três planetas internos classificados como super-Terras, um dos quais transita em frente à estrela.
The Sparkler: Evolved High-redshift Globular Cluster Candidates Captured by JWSTSérgio Sacani
This document discusses compact red sources detected around a strongly lensed galaxy ("the Sparkler") at a redshift of 1.378 using JWST data. Photometry and morphological fits of the sources suggest they are spatially unresolved, very red, and consistent with old stellar populations. Spectroscopy shows emission from the galaxy but no signs of star formation in the red sources. The sources are most likely evolved globular clusters dating back to formation redshifts between 7-11, corresponding to ages of 3.9-4.1 billion years at the time of observation. If confirmed, these would be the first observed globular clusters at high redshift, opening a window into early globular cluster formation in the first billion years of
Star formation at the smallest scales; A JWST study of the clump populations ...Sérgio Sacani
We present the clump populations detected in 18 lensed galaxies at redshifts 1 to 8.5 within the lensing cluster field SMACS0723.
The recent JWST Early Release Observations of this poorly known region of the sky have revealed numerous point-like sources
within and surrounding their host galaxies, undetected in the shallower HST images. We use JWST multiband photometry and
the lensing model of this galaxy cluster to estimate the intrinsic sizes and magnitudes of the stellar clumps. We derive optical
restframe effective radii from <10 to hundreds pc and masses ranging from ∼ 105
to 109 M, overlapping with massive star
clusters in the local universe. Clump ages range from 1 Myr to 1 Gyr. We compare the crossing time to the age of the clumps
and determine that between 45 and 60 % of the detected clumps are consistent with being gravitationally bound. On average,
the dearth of Gyr old clumps suggests that the dissolution time scales are shorter than 1 Gyr. We see a significant increase in the
luminosity (mass) surface density of the clumps with redshift. Clumps in reionisation era galaxies have stellar densities higher
than star clusters in the local universe. We zoom in into single galaxies at redshift < 6 and find for two galaxies, the Sparkler and
the Firework, that their star clusters/clumps show distinctive colour distributions and location surrounding their host galaxy that
are compatible with being accredited or formed during merger events. The ages of some of the compact clusters are between
1 and 4 Gyr, e.g., globular cluster precursors formed around 9-12 Gyr ago. Our study, conducted on a small sample of galaxies,
shows the potential of JWST observations for understanding the conditions under which star clusters form in rapidly evolving
galaxies.
TOI-4600 b and c: Two Long-period Giant Planets Orbiting an Early K DwarfSérgio Sacani
We report the discovery and validation of two long-period giant exoplanets orbiting the early K dwarf TOI-4600
(V = 12.6, T = 11.9), first detected using observations from the Transiting Exoplanet Survey Satellite (TESS) by
the TESS Single Transit Planet Candidate Working Group. The inner planet, TOI-4600 b, has a radius of
6.80 ± 0.31 R⊕ and an orbital period of 82.69 days. The outer planet, TOI-4600 c, has a radius of 9.42 ± 0.42 R⊕
and an orbital period of 482.82 days, making it the longest-period confirmed or validated planet discovered by
TESS to date. We combine TESS photometry and ground-based spectroscopy, photometry, and high-resolution
imaging to validate the two planets. With equilibrium temperatures of 347 K and 191 K, respectively, TOI-4600 b
and c add to the small but growing population of temperate giant exoplanets that bridge the gap between hot/warm
Jupiters and the solar system’s gas giants. TOI-4600 is a promising target for further transit and precise RV
observations to measure the masses and orbits of the planets as well as search for additional nontransiting planets.
Additionally, with Transit Spectroscopy Metric values of ∼30, both planets are amenable for atmospheric
characterization with JWST. Together, these will lend insight into the formation and evolution of planet systems
with multiple giant exoplanets.
Kepler-1647b is the largest and longest-period Kepler transiting circumbinary planet discovered to date. It orbits an eclipsing binary star system with an orbital period of approximately 1100 days, making it one of the longest-period transiting planets known. The planet is around 1.06 times the size of Jupiter and perturbes the times of the stellar eclipses, allowing its mass to be measured at 1.52 times that of Jupiter. Despite its long orbital period compared to Earth, the planet resides in the habitable zone of the binary star system throughout its orbit. The discovery of this unusual planetary system provides insights into theories of planet formation and dynamics in multiple star systems.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
The Exoplanet Radius Valley from Gas-driven Planet Migration and Breaking of ...Sérgio Sacani
This paper aims to test whether the exoplanet radius valley can be explained by planet formation models, particularly the gas-driven migration model. The migration model proposes that planets formed in resonant chains during the gas disk phase and most chains became unstable after gas dispersal, leading to collisions. Simulations of this model produce systems with rocky, water-rich, or mixed compositions. By combining the simulation outcomes with mass-radius relationships and assuming atmospheric loss in late impacts, the authors show the migration model can account for the observed bimodal radius distribution and uniform sizes within systems. This suggests planets around 1.4 Earth radii are rocky while those around 2.4 Earth radii contain water, challenging an exclusively rocky composition for "mini-Neptunes
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
2. Temperate Earth-size planet Gliese 12 b 1277
MNRAS 531, 1276–1293 (2024)
and-narrow observing strategy of Kepler, TESS observes a much
larger 2300 deg2
area of the sky using its four refractive 10 cm
CCD cameras, with sky coverage divided in time into ‘sectors’ with
durations of 27.4 d. This means that TESS is sensitive to short-period
planets orbiting bright stars. Furthermore, the red-optimized 600–
1000 nm TESS bandpass increases its photometric sensitivity for
cool stars such as M-dwarfs (Ricker et al. 2014).
TESS has discovered a significant number of small exoplanets
orbiting M-dwarfs throughout both its two-year prime mission and
subsequent extended mission (e.g. Günther et al. 2019; Kostov
et al. 2019; Luque et al. 2019; Vanderspek et al. 2019; Win-
ters et al. 2019; Cloutier et al. 2020; Gan et al. 2020; Gilbert
et al. 2020; Shporer et al. 2020; Burt et al. 2021; Cloutier et al.
2021; Trifonov et al. 2021; Silverstein et al. 2022; Gilbert et al.
2023). TESS detections have demonstrated that terrestrial planets
are common around the nearest M-dwarfs (Ment Charbon-
neau 2023), though the number of these planets detected around
mid-late M-dwarfs (0.3 R) is lower than anticipated (Brady
Bean 2022). Now in its sixth year of operations, TESS contin-
ues to extend its observational baseline as it re-observes much
of the sky. This enables the discovery of new exoplanets with
longer orbital periods and, hence, lower equilibrium tempera-
tures.
The CHaracterizing ExOPlanets Satellite (CHEOPS; Benz et al.
2021) has found great success in taking precise transit photometry
and determining accurate planetary parameters of TESS discoveries
that enables further characterization by JWST and other instruments
(Lacedelli et al. 2022; Wilson et al. 2022; Tuson et al. 2023;
Fairnington et al. 2024; Palethorpe et al. 2024). CHEOPS utilizes
a 30 cm telescope to perform high-precision, targeted photometry
in order to refine transit ephemerides, ascertain orbital periods, and
improve on the radius precision of planets detected by TESS and
other transit surveys (Benz et al. 2021), as well discovering new
planets. The larger aperture of CHEOPS compared to TESS also
provides high-signal-to-noise transits that may be challenging or
impossible to obtain from the ground. Due to TESS’s scanning
strategy, transits of longer period exoplanets are often missed,
rendering the orbital period ambiguous. Follow-up observations
by CHEOPS can ascertain the orbital periods of these planets.
A network of ground-based photometers and spectrographs also
complements CHEOPS in targeting TESS Objects of Interest (TOIs)
in order to confirm, validate, and refine the characteristics of the
systems.
In this work, we present the discovery of a temperate (F
= 1.6 ± 0.2 S⊕) Earth-sized (Rb = 1.0 ± 0.1 R⊕) planet orbiting the
M-dwarf Gliese 12 found and validated through TESS and CHEOPS
observations. Gliese 12 is bright (V = 12.6 mag, K = 7.8 mag), nearby
(12.162 ± 0.005 pc), and is characterized by low-magnetic activity;
these factors establish Gliese 12 b as a prime target for further
characterization, such as mass measurement via RV observations
and atmospheric study through transmission spectroscopy.
We organize this work as follows: In Section 2, we de-
tail the space- and ground-based photometry, spectroscopy, and
imaging data for this target. In Section 3, we compile and de-
rive the properties of Gliese 12. Section 4 enumerates and pre-
cludes the possible scenarios of a false-positive exoplanet detec-
tion with the available data, validating Gliese 12 b as a gen-
uine exoplanet. We then describe our approach to modelling
the transits of Gliese 12 b from the available data in Sec-
tion 5. In Section 6, we comment on Gliese 12 b’s prospects
for further study, including future mass measurement, atmospheric
characterization, and this target’s utility to exoplanet demog-
raphy. Finally, in Section 7, we summarize and conclude the
work.
2 OBSERVATIONS
2.1 Photometry
2.1.1 TESS
Gliese 12 (TIC 52005579, TOI-6251) was first observed by TESS
during ecliptic plane observations in sectors 42 and 43 of year 4 in
its first extended mission (Ricker et al. 2014; Ricker 2021), between
2021 August 21 and 2021 October 11 (BJD 2459447.19 – BJD
2459498.39). It was then re-observed during sector 57 of year 5 in
the second TESS extended mission between 2022 September 30 and
2022 October 29 (BJD 2459852.85 – BJD 2459881.62). Over a total
of 82.2 d, TESS observations of Gliese 12 were combined into 20 s
cadence target pixel frames.1
The data observed in sector 42 were
taken on CCD 2 of camera 2, whilst the data observed in sectors 43
and 57 were taken on CCD 3 of camera 1.
The data were processed in the TESS Science Processing Op-
erations Centre (SPOC; Jenkins et al. (2016)) pipeline at NASA
Ames Research Centre. The SPOC conducted a transit search of
the TESS data upto sector 57 on 2023 February 04 with an adaptive,
noise-compensating matched filter (Jenkins 2002; Jenkins et al. 2010,
2020). The search identified a Threshold Crossing Event (TCE) with
12.76148 d period. The TCE was reported with a Multiple Event
Statistic (MES) S/N statistic of 8.0, above the lower limit of 7.1
required for a TCE to undergo further vetting. An initial limb-
darkened transit model was fitted (Li et al. 2019) and a suite of
diagnostic tests were conducted to help assess the planetary nature
of the signal (Twicken et al. 2018). The transit depth associated
with the TCE was 1180 ± 173 ppm. Inspection of the SPOC Data
Validation (DV) report reveals two possible periods for the transit
signal, either 12.76 d or a factor of two larger (25.52 d), due to gaps
in the photometry coincident with alternating transits.
TESS photometry in sectors 42 and 43 was strongly affected
by crossings of the Earth and Moon in the field-of-view (Faus-
naugh et al. 2021a, b). As a result observations of Gliese 12 in
both sectors contain large mid-sector gaps, 7.6 d between BJD
2459453.64 – BJD 2459461.24 in sector 42 and 5.1 d between
BJD 2459482.11 – BJD 2459487.19 in sector 43 (Fig. 1), and
there is likewise a large observing gap between the two sec-
tors. The phasing of these gaps means that only one transit
of the Gliese 12 planet candidate (BJD 2459497.18) was ob-
served, with up to 3 transits falling outside of active observa-
tion. During sector 57 TESS entered safe mode for 3.13 d be-
tween BJD 2459863.28 – BJD 2459866.41; there are also three
smaller gaps for data downlinks between BJD 2459860.58 –
BJD 2459860.80, BJD 2459867.25 – BJD 2459867.47, and BJD
2459874.61 – BJD 2459874.82, spanning a total of 0.63 d (Faus-
naugh et al. 2022). Two transits were successfully observed towards
the beginning and end of sector 57 (BJD 2459854.51 and BJD
2459880.03), however the location of a possible transit at BJD
2459867.27 falls into the data gap caused by the second data
downlink.
1This star has been observed by TESS as part of Guest Investigator pro-
grammes G04033 (PI: Winters), G04148 (PI: Robertson), G04191 (PI: Burt),
G04211 (PI: Marocco), and G04214 (PI: Cloutier) in year 4; programmes
G05087 (PI: Winters), G05109 (PI: Marocco), and G05152 (PI: Cloutier) in
year 5; and programme G06131 (PI: Shporer) in year 6.
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Figure 1. TESS photometry of Gliese 12. Figure shows the 20 s cadence PDCSAP light curve for sectors 42, 43, and 57 and the 120 s cadence PDCSAP light
curve for sector 70, where systematic errors have been removed, but the resulting light curve has not been corrected for low-frequency variations such as stellar
activity. Overplotted are the possible periods of the transiting planet, where the red solid line shows the transit centre, the orange dashed-dotted lines shows
times consistent with a 12.76 and 25.52 d period, and the solid orange line shows times consistent with only a 12.76 d period.
The incidence of these data gaps, visualized in Fig. 1, caused
the initial ambiguity in the orbital period between 12.76 and
25.52 d. Despite this uncertainty, the TCE passed an initial triage
with the TESS-ExoClass (TEC) classification algorithm2
and was
subsequently vetted by the TESS team. The TCE was then duly
promoted to TOI (Guerrero et al. (2021)) planet candidate status
and alerted as TOI-6251.01 on 2023 April 03. The TOI was alerted
with the 25.52 d period, but a note was included on the factor-of-two
orbital period ambiguity.
TESS observed Gliese 12 again in sector 70, during its second
ecliptic plane survey in year 6. Observations were captured with a
120 s cadence on CCD 3 of camera 2 between 2023 September 20
and 2023 October 16 (BJD 2460208.79 – BJD 2460232.97). The
TESS sector 70 photometry covers two consecutive transits of TOI-
6251.01 (also known as Gliese 12 b) separated by 12.76 d, confirming
the short-period orbital solution.
For the photometric analysis, we download the TESS photometry
from the Mikulski Archive for Space Telescopes (MASTs)3
and
use the Pre-search Data Conditioning Simple Aperture Photometry
(PDCSAP; Smith et al. (2012); Stumpe et al. (2012, 2014)) light-
curve reduced by the SPOC. We use the quality flags provided by the
SPOC pipeline to filter out poor-quality data.
2.1.2 CHEOPS
To confirm and characterize the planet in the Gliese 12 system we
obtained five visits covering transits of planet b with the CHEOPS
spacecraft (Benz et al. 2021) through the CHEOPS AO-4 guest
observers programmes with ID:07 (PI: Palethorpe) and ID:12 (PI:
Venner). The observation log for our CHEOPS observations is
presented in Table 1.
2https://github.com/christopherburke/TESS-ExoClass
3https://archive.stsci.edu/tess
The data were processed using the CHEOPS Data Reduction
Pipeline (DRP 14.1.3; Hoyer et al. 2020) that conducts frame
calibration, instrumental and environmental correction, and aperture
photometry using a pre-defined range of radii (R = 15–40
). For
all visits of Gliese 12 we selected the DEFAULT aperture, which
has a radius of 25 pixels. The DRP produced flux contamination
(see Hoyer et al. 2020 and Wilson et al. 2022 for computation
and usage) that was subtracted from the light curves. We retrieved
the data and corresponding instrumental bases vectors, assessed the
quality using the pycheops PYTHON package (Maxted et al. 2022),
and decorrelated with the parameters suggested by this package,
which can be found in Table 1. Outliers were also trimmed from the
light curves, with points that were 4σ away from the median value
removed. We then used these detrended data for further analysis.
Table 3 shows which of the possible periods the various CHEOPS
transits cover, whilst three of the transits observed occurred when
both a 12.76 and 25.5 d period were possible, a further two transits
were observed when only a 12.76 d period was possible, confirming
this as the orbital period of Gliese 12 b.
2.1.3 MINERVA-Australis
We used three telescopes of the MINERVA-Australis array (Addison
et al. 2019) in clear bands to simultaneously observe a full transit of
Gliese 12 b on the night of 2023 September 11. Telescopes 1 and 2
are both equipped with ZWO1600 CMOS cameras, each with a field
of view of 27’ × 18’, and plate scale of 0.67 arcsec pixel–1
. Telescope
3 is equipped with ZWO295 CMOS camera, with a field-of-view of
21’ × 14’, and a plate scale of 0.3 arcsec pixel–1
. We used exposure
durations of 30 s for Telescope 1 and 2 and 60 s for telescope 3.
We used astroImageJ (Collins et al. 2017) to extract the light
curves. The aperture radii are ∼8.7” for all three telescopes. The
observation of telescope 3 was interrupted during the transit event,
therefore did not achieve the necessary precision for the independent
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Table 1. Log of CHEOPS Observations of Gliese 12 b. The column Texp gives the exposure time in terms of the integration time per image multiplied
by the number of images stacked onboard prior to download. Nobs is the number of frames. Effic. is the proportion of the time in which unobstructed
observations of the target occurred. Rap is the aperture radius used for the photometric extraction. RMS is the standard deviation of the residuals from the
best fit after the DRP has been applied. The variables in the final column are as follows: time, t; spacecraft roll angle, φ, PSF centroid position, (x, y);
smear correction, smear; aperture contamination, contam; image background level, bg.
Start date Duration Texp Nobs Effic. File key APER Rap RMS Decorrelation
(UTC) (h) (s) (per cent) (pixels) (ppm)
2023 Sep 24, T00:04 11.41 60 513 74.9 CH PR240007 DEFAULT 25 801 sin(φ), cos(φ),
TG000101 V0300 contam, smear, bg
2023 Oct 06, T18:20 12.76 60 481 62.8 CH PR240007 DEFAULT 25 846 t, t2, x, x2, y, y2, sin(φ),
TG000102 V0300 sin(2φ), cos(φ), cos(2φ),
contam, smear, bg
2023 Oct 19, T16:33 6.80 60 222 54.3 CH PR240012 DEFAULT 25 752 t2, contam, smear, bg
TG000701 V0300
2023 Nov 14, T06:30 6.92 60 241 57.9 CH PR240012 DEFAULT 25 910 t, x, y, sin(φ), cos(φ), bg
TG000702 V0300
2023 Nov 27, T18:35 7.44 60 248 55.5 CH PR240012 DEFAULT 25 1114 t, x, y, sin(φ), cos(φ), bg
TG000101 V0300
detection of the transit. Thus, we do not include data from telescope
3 for our global analysis. We detrend using the x- and y-positions,
airmass, and quadratic time-series terms. A log of these observations
and decorrelations can be found in Table 2, and the possible period
of the transiting planet covered by these observations can be found
in Table 3.
2.1.4 SPECULOOS
We observed two transits of Gliese 12 b with the SPECULOOS
Southern Observatory (SSO; Delrez et al. 2018; Gillon 2018; Jehin
et al. 2018; Murray et al. 2020; Sebastian et al. 2021). SSO is
composed of four 1 m-class telescopes named after the Galilean
moons (Io, Europa, Ganymede, and Callisto), it is located at ESO
Cerro Paranal Observatory in Chile. The telescopes are identical,
each equipped with a 2K×2K Andor CCD camera with a pixel scale
of 0.35
pixel–1
, resulting in a field-of-view of 12
× 12
. We obtained
a transit of Gliese 12 b on 2023 September 23 with Europa with
10 s exposures in the Sloan-r’ filter, totalling 1213 measurements.
A second transit was obtained simultaneously with Io, Europa and
Ganymede on the 2023 November 26, also with 10 s exposures in
the Sloan-r’ filter. These observations represent 754, 741, and 751
measurements, respectively. All the data analysis was done using
a custom pipeline built with the prose4
package (Garcia et al.
2021, 2022). We performed differential photometry and the optimum
apertures were 3.26
, 3.45
, 3.23
, and 3.17
, respectively for the
Europa observation on the night of the 2023 September 23, and the Io,
Europa, and Ganymede observations on the night of 2023 November
26. A log of these observations and their decorrelation parameters
can be found in Table 2, and the possible period of the transiting
planet covered by these observations can be found in Table 3.
2.1.5 Purple Mountain Observatory
We observed one transit with Purple Mountain Observatory (PMO)
on the night of 2023 September 01. The telescope is an 80 cm
azimuthal-mounting high-precision telescope at PMO Yaoan Station
in Yunnan Province, in the south-west of China. The telescope’s
field of view is 11.8 arcmin. It is a Ritchey–Chretien telescope
4https://github.com/lgrcia/prose
with a 2048×2048 pixel PI CCD camera. The spatial resolution
for each axis is 0.347 arcsec pixel–1
. We used the Ic broad-band filter
for the observation. The cadence of the observations was 55 s and
the exposure time was 50 s. A log of these observations and their
decorrelation parameters can be found in Table 2, and the possible
period of the transiting planet covered by these observations can be
found in Table 3.
2.2 Spectroscopy
2.2.1 TRES
We obtained an additional 4 observations of Gliese 12 via the
Tillinghast Reflector Echelle Spectrograph (TRES; Fűrész, Szentgy-
orgyi Meibom (2008)) on the 1.5 m reflector at the Fred Lawrence
Whipple Observatory in Arizona, USA. TRES is a fibre-fed echelle
spectrograph with a spectral resolution of 44 000 over the wavelength
range of 390–910 nm. The observations were taken between 2016
October 13 and 2021 September 11 as part of the M-dwarf survey
of Winters et al. (2021), using the standard observing procedure
of obtaining a set of three science observations surrounded by
ThAr calibration spectra. The science spectra were then combined
to remove cosmic rays and wavelength calibrated using the ThAr
spectra, with the extraction technique following procedures outlined
in Buchhave et al. (2010). The spectra had signal-to-noise ratios
(SNRs) in the range 20–24 (average SNR = 21) at ∼716 nm and are
presented in Appendix Table A1.
2.2.2 HARPS-N
We obtained 13 spectra for Gliese 12 with the HARPS-N spec-
trograph (R = 115 000) (Cosentino et al. 2012) installed on the
3.6 m Telescopio Nazionale Galileo (TNG) at the Observatorio de
los Muchachos in La Palma, Spain. These observations were taken
between 2023 August 09 and 2023 October 01 (BJD 2460165.66
– BJD 2460218.56) as part of the HARPS-N Collaboration’s Guar-
anteed Time Observations (GTOs) programme. The observational
strategy consisted of exposure times of 1800 s per observation. We
obtained spectra with SNR in the range 12–35 (average SNR = 25)
at 550 nm.
The spectra were reduced with two different methods. The first
used version 2.3.5 of the HARPS-N Data Reduction Software (DRS)
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Table 2. Log of ground-based photometric observations of Gliese 12 b. The column Texp gives the exposure time in terms of the integration time per image
multiplied by the number of images stacked onboard prior to download. Nobs is the number of frames. The variables in the final column are as follows: time,
t; position of the target star on the CCD (x, y), and the full width at half-maximum (FWHM) of the PSF.
Start date Duration Texp Nobs Observatory/Telescope Decorrelation
(UTC) (h) (s)
2023 Sep 11, T11:39 3.852 30.0 197 MINERVA T1 t, x, y, airmass
2023 Sep 11, T11:39 3.852 60.0 266 MINERVA T2 t, x, y, airmass
2023 Sep 24, T01:30 7.019 10.0 1207 SPECULOOS Europa t2, x2
2023 Nov 01, T13:01 3.000 55.0 210 PMO x, y, FWHM
2023 Nov 27, T00:01 4.251 10.0 754 SPECULOOS Io airmass, FWHM
2023 Nov 27, T00:02 4.234 10.0 741 SPECULOOS Europa t
2023 Nov 27, T00:02 4.239 10.0 751 SPECULOOS Ganymede t
Table 3. Log of photometric observations of Gliese 12 b relative to the
possible period of the transiting planet. The Period column relates to the
period ambiguity surrounding Gliese 12 b, where T0 refers to the transit
centre time of BJD 2459497.185, P1 refers to the possible 12.76 d period, and
P2 refers to the possible 25.5 d period.
Date Observatory/Telescope Period
(UTC)
2023 Sep 11 MINERVA (T1, T2) T0 + 55 P1
2023 Sep 24 CHEOPS T0 + 56 P1 or T0 + 28 P2
2023 Sep 24 SPECULOOS (Europa) T0 + 56 P1 or T0 + 28 P2
2023 Oct 06 CHEOPS T0 + 57 P1
2023 Oct 19 CHEOPS T0 + 58 P1 or T0 + 29 P2
2023 Nov 01 PMO T0 + 59 P1
2023 Nov 14 CHEOPS T0 + 60 P1 or T0 + 30 P2
2023 Nov 27 CHEOPS T0 + 61 P1
2023 Nov 27 SPECULOOS (Europa, T0 + 61 P1
Ganymede, Io)
(Dumusque et al. 2021), with a M4 mask used in the cross-correlation
function (CCF), resulting in an RV RMS of 2.60 ms–1
and RV
precision of 2.95 ms–1
. The second method used was the line-by-
line (LBL) method (Artigau et al. 2022). The LBL code5
performs a
simple telluric correction by fitting a TAPAS model (Bertaux et al.
2014), and has been shown to significantly improve the RV precision
of M-dwarfs observed with optical RV spectrographs (Cloutier et al.
2024). The LBL method resulted in an average RV RMS of 2.69 ms–1
,
which is similar to that of the CCF method, however the average RV
precision significantly improved to 1.15 ms–1
.
The HARPS-N data are presented in Appendix Table A2, which
includes the radial velocities as well as the activity indicators: FWHM
of the CCF, the line Bisector Inverse Slope (BIS), H α, and the
log R
HK converted from the S-index following Suárez Mascare˜
no
et al. (2015). RV observations with HARPS-N are still currently
ongoing with the GTO programme and will be presented in a mass
determination paper at a later date.
2.3 High resolution imaging
As part of our standard process for validating transiting exoplanets to
assess the possible contamination of bound or unbound companions
on the derived planetary radii (Ciardi et al. 2015), we observed
Gliese 12 with high-resolution near-infrared adaptive optics (AO)
imaging at Keck Observatory and with optical speckle observations at
WIYN.
5https://github.com/njcuk9999/lbl, version 0.61.0.
2.3.1 Optical speckle at WIYN
We observed Gliese 12 on 2018 November 21 using the NN-
EXPLORE Exoplanet Stellar Speckle Imager (NESSI; Scott et al.
(2018)) at the WIYN 3.5 m telescope on Kitt Peak. NESSI is a dual-
channel instrument and obtains a simultaneous speckle measurement
in two filters. In this case, we used filters with central wavelengths
of λc = 562 and 832 nm. The speckle data consisted of 5 sets of
1000 40 ms exposures in each filter, centred on Gliese 12. These
exposures were limited to a 256 × 256 pixel read-out section in each
camera, resulting in a 4.6 × 4.6 arcsec field-of-view. Our speckle
measurements, however, are further confined to an outer radius of
1.2 arcsec from the target star due the fact that speckle patterns lose
sufficient correlation at wider separation. To calibrate the shape of
the PSF, similar speckle data were obtained of a nearby single star
immediately prior to the observation of Gliese 12.
We reduced the speckle data using a pipeline described by Howell
et al. (2011). Among the pipeline products is a reconstructed image of
the field around Gliese 12 in each filter. The reconstructed images are
the basis of the contrast curves that set detection limits on additional
point sources that may lie in close proximity to Gliese 12. These
contrast curves are measured based on fluctuations in the noise-like
background level as a function of separation from the target star.
The data, including reconstructed images, were inspected to find any
detected companion stars to Gliese 12, but none were found. We
present the reconstructed images and contrast limits in Fig. 2.
2.3.2 Near-infrared AO at Keck
The observations were made with the NIRC2 instrument on Keck-II
behind the natural guide star AO system (Wizinowich et al. 2000)
on 2023 August 05 in the standard 3-point dither pattern that is
used with NIRC2 to avoid the left lower quadrant of the detector
which is typically noisier than the other three quadrants. The dither
pattern step size was 3
and was repeated twice, with each dither
offset from the previous dither by 0.5
. NIRC2 was used in the
narrow-angle mode with a full field-of-view of ∼10
and a pixel
scale of approximately 0.0099442
pixel–1
. The Keck observations
were made in the Kcont filter (λo = 2.2706; λ = 0.0296 μm) with
an integration time in each filter of 1 s for a total of 9 s. Flat fields
were generated from a median average of dark subtracted dome flats.
Sky frames were generated from the median average of the 9 dithered
science frames; each science image was then sky-subtracted and flat-
fielded. The reduced science frames were combined into a single
combined image using a intrapixel interpolation that conserves flux,
shifts the individual dithered frames by the appropriate fractional
pixels; the final resolution of the combined dithers was determined
from the FWHM of the point-spread function; 0.049
. To within the
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Figure 2. The 5σ contrast curves of WIYN/NESSI speckle high-resolution
images at 562 nm (blue) and 832 nm (red), with insets showing the central
region of the images centred on Gliese 12.
Figure 3. Companion sensitivity for the near-infrared AOs imaging. The
black points represent the 5σ limits and are separated in steps of 1 FWHM; the
purple represents the azimuthal dispersion (1σ) of the contrast determinations
(see text). The inset image is of the primary target showing no additional
close-in companions.
limits of the AO observations, no stellar companions were detected.
The final 5σ limit at each separation was determined from the average
of all of the determined limits at that separation and the uncertainty
on the limit was set by the rms dispersion of the azimuthal slices at
a given radial distance (Fig. 3).
3 STELLAR PROPERTIES
Here, we present our determinations of the stellar properties of Gliese
12. Our adopted parameters are summarized in Table 4.
3.1 Stellar parameters
We estimate the mass and radius of Gliese 12 using the empirical
relations of Mann et al. (2015, 2019). To begin, we used the
Ks-band apparent magnitude from 2MASS (7.807 ± 0.020 mag;
Skrutskie et al. 2006) and the stellar distance from the Gaia DR3
parallax (12.162 ± 0.005 pc; Gaia Collaboration et al. 2023), to
derive the corresponding absolute Ks-band magnitude of MKs =
7.382 ± 0.020 mag. Using Mann et al. (2019, equation 2 and tables
6 7) we convert this into a stellar mass M = 0.241 ± 0.006 M
(2.4 per cent uncertainty), and with Mann et al. (2015, table 1 and
equation 4) we determine R = 0.269 ± 0.008 R (3.0 per cent
uncertainty). From these values for the mass and radius we derive
the stellar density ρ = 17.55+1.60
−1.42 g cm−3
(9 per cent uncertainty) and
surface gravity log g = 4.96 ± 0.03 cm s−2
.
Our stellar mass and radius agree well with the values adopted
in the TESS Input Catalogue (TIC; M = 0.242 ± 0.020 M, R =
0.269 ± 0.008 R; Stassun et al. 2019), which is unsurprising as the
TIC Cool Dwarf list uses the Mann et al. (2015, 2019) MKs relations
to calculate these parameters (Stassun et al. 2019). However, our
estimate for the stellar density has a larger uncertainty than the TIC
value (17.46 ± 0.12 g cm−3
). The constraint on this parameter (0.7
per cent uncertainty) appears implausibly precise considering the
mass and radius uncertainties, so we prefer our characterization of
the stellar density precision. As we use priors on the stellar density
in our transit fits this bears significance for our global models (on
which see Section 5).
To further constrain the fundamental parameters of Gliese 12, we
perform a fit to the stellar spectral energy distribution (SED). We use
the astroARIADNE PYTHON package (Vines Jenkins 2022) to
fit the broad-band photometry of Gliese 12 to the following stellar
atmosphere models: BTSettl-AGSS2009 (Allard, Homeier Freytag
2011), Kurucz (Kurucz 1992), and Castelli Kurucz (ATLAS9)
(Castelli Kurucz 2003). This algorithm uses a Bayesian Model
Averaging method to derive best fit stellar parameters from the
weighted average of each model’s output. This is to mitigate the
biases present in an individual model that correlate with the star’s
spectral type. Additionally, mass and age are estimated via MIST
isochrones (Choi et al. 2016). We assign a broad Gaussian prior
of 3376 ± 157 K on Teff from the TIC (Stassun et al. 2019), and
a prior of [Fe/H] = −0.29 ± 0.09 from Maldonado et al. (2020).
From this analysis, we find values of Teff = 3253 ± 55 K and L =
0.0074 ± 0.008 L for Gliese 12, which we adopt in Table 4.
3.2 Kinematics
We calculate the space velocities of Gliese 12 relative to the sun
following Johnson Soderblom (1987), adopting stellar positions
and velocities as in Table 4. We find (U, V, W) = (−51.11 ± 0.02,
+27.31 ± 0.03, −31.62 ± 0.04) km s−1
, where U is defined as
positive in the direction of the galactic centre, V is positive towards
the galactic rotation, and W is positive in the direction of the north-
galactic pole. Assuming values for the solar space velocities from
Schönrich, Binney Dehnen (2010), we then find space motions
relative to the local standard of rest of (ULSR, VLSR, WLSR) =
(−40.0 ± 0.8, +39.5 ± 0.5, −24.3 ± 0.4) km s−1
. Following the
membership probabilities established by Bensby, Feltzing Lund-
ström (2003) these kinematics, in particular the strongly positive
value of VLSR, are consistent only with thin-disc membership for
Gliese 12. However, its kinematics are comparatively hot for a thin-
disc star; its Vtot ≡
U2
LSR + V 2
LSR + W2
LSR ≈ 61 km s−1
belongs to
the upper end of values found among nearby M-dwarfs (Newton
et al. 2016; Medina et al. 2022). This suggests a relatively old age
for Gliese 12.
We may extend this further by employing quantitative UVW–age
relationships, such as that of Almeida-Fernandes Rocha-Pinto
(2018) or Veyette Muirhead (2018). These two relations are
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Table 4. Stellar parameters of Gliese 12.
Parameter Value Reference
Gliese 12 Gliese (1956, 1969)
Giclas (G) 32–5 Giclas, Slaughter Burnham (1959); Giclas, Burnham Thomas (1971)
LHS 1050 Luyten (1976)
2MASS 00154919 + 1333218 Skrutskie et al. (2006)
Gaia DR3 2 768 048 564 768 256 512 Gaia DR3
TIC 52 005 579 Stassun et al. (2019)
TOI 6251 Guerrero et al. (2021)
R.A. 00:15:49.24 Gaia DR3
Dec. + 13:33:22.32 Gaia DR3
(mas) 82.194 ± 0.032 Gaia DR3
Distance (pc) 12.162 ± 0.005 Derived
μα (mas yr−1) +618.065 ± 0.039 Gaia DR3
μδ (mas yr−1) +329.446 ± 0.034 Gaia DR3
RV (km s−1) +51.213 ± 0.0036 Soubiran et al. (2018)
U (km s−1) −51.11 ± 0.02 This work
V (km s−1) +27.31 ± 0.03 This work
W (km s−1) −31.62 ± 0.04 This work
Spectral type M3.5V Lépine et al. (2013)
M4V Newton et al. (2014)
G (mag) 11.399 ± 0.003 Gaia DR3
BP (mag) 12.831 ± 0.003 Gaia DR3
RP (mag) 10.227 ± 0.004 Gaia DR3
B (mag) 14.265 ± 0.038 Stassun et al. (2019)
V (mag) 12.600 ± 0.042 Stassun et al. (2019)
T (mag) 10.177 ± 0.007 Stassun et al. (2019)
J (mag) 8.619 ± 0.002 Skrutskie et al. (2006)
H (mag) 8.068 ± 0.026 Skrutskie et al. (2006)
Ks (mag) 7.807 ± 0.020 Skrutskie et al. (2006)
M (M) 0.241 ± 0.006 This work
R (R) 0.269 ± 0.008 This work
ρ (g cm−3) 17.55+1.60
−1.42 This work
log g (cm s−2) 4.96 ± 0.03 This work
Teff (K) 3253 ± 55 This work
L (L) 0.0074 ± 0.0008 This work
[Fe/H] (dex) −0.29 ± 0.09 Maldonado et al. (2020)
Age (Gyr) 7.0+2.8
−2.2 This work
log R
HK −5.68 ± 0.12 This work
calibrated to the UVW velocity dispersion-versus-isochrone age for
the sun-like stars from the Geneva–Copenhagen survey (Nordström
et al. 2004; Casagrande et al. 2011). For the measured UVW space
velocities of Gliese 12, these relations return kinematic ages of
6.3+4.1
−3.1 Gyr (Almeida-Fernandes Rocha-Pinto 2018) or 7.0+2.8
−2.2 Gyr
(Veyette Muirhead 2018). These estimates are consistent with an
older, most likely super-solar age for Gliese 12. We adopt the age
from the Veyette Muirhead (2018) relation for this star.
3.3 Stellar activity
We measured the S-index of Gliese 12 from the 13 HARPS-N spectra
(Appendix Table A2) and, following the method outlined in Suárez
Mascare˜
no et al. (2015), used them to compute the values of log R
HK .
During the observation span of Gliese 12, we find an average log R
HK
of −5.68 ± 0.12. In comparison with the M-dwarf sample studied
by Mignon et al. (2023), Gliese 12 lies far towards the lower end
of the observed distribution in log R
HK . The S-index and associated
log R
HK are traditionally seen as an excellent indicator for a star’s
magnetic cycle and overall activity level, implying a low-level of
stellar activity for Gliese 12.
We also use the average value of log R
HK to estimate the expected
rotational period of Gliese 12. Using the log R
HK − Prot relation
for M3.5–M6 dwarfs from Suárez Mascare˜
no et al. (2018), we find
an estimated rotational period of 132+37
−25 d. We point out that this
estimate comes from a calibration relation and that the true rotation
period may thus be outside these bounds. The rotational period of
Gliese 12 has previously been measured from MEarth photometry
as 78.5 d (Irwin et al. 2011) or 81.2 d (Newton et al. 2016). There
are various possibilities for the discrepancies between the Suárez
Mascare˜
no et al. (2018) prediction and measured values, for example,
the manifestation of the rotation period in the data may not be the
same as the physical rotation period (Nava et al. 2020). Alternatively,
the log R
HK of Gliese 12 varies over time due to a magnetic cycle
(Mignon et al. 2023), therefore if it has been presently observed at a
low value, then the predicted rotational period could be brought into
agreement with the observed one.
Finally, we performed a Bayesian Generalized Lomb–Scargle
(BGLS) analysis (Boisse et al. 2011; Mortier et al. 2015) on the TESS
SAP and PDCSAP photometry to search for any stellar variability,
but did not detect any significant modulation. However, this analysis
is adversely affected by the short ∼27 d baseline of the TESS sectors.
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Figure 4. Historical images of the field surrounding Gliese 12. Left: 2MASS
J band image from 1998 (Skrutskie et al. 2006) Right: DSS image from 1949
(Lasker et al. 1990). The blue circle indicate the location of Gliese 12 when
it was observed by TESS. The blue cross indicates the location of Gliese 12
when it was observed by 2MASS. Blue dots indicate all the other stars in
the field-of-view within T Mag 7.5 of Gliese 12. A background eclipsing
binary that can mimic the 1.1 ppt transit signal needs to be within T Mag
7.5 of Gliese 12. These images can be used to rule out the existence of such
stars when TESS is observing Gliese 12.
Visual inspection of the TESS light-curves also shows no significant
evidence for flares, which is expected for inactive M-dwarfs in TESS
(Medina et al. 2020) and consistent with a low-magnetic activity level
for Gliese 12. This is consistent with the picture of an old stellar age
(Medina et al. 2022).
4 PLANET VALIDATION
To ascertain the planetary nature of Gliese 12 b, we enumerate below
several false-positive scenarios that we can rule out from the available
evidence:
(i) The discovery transit event is not an artefact of TESS instrument
systematics: We can rule this out from five independent CHEOPS
visits and three ground-based observations that successfully detect a
transit.
(ii) Gliese 12 b is not a stellar companion: The radial velocities
from the TRES spectra, presented in Appendix Table A1, vary by
only 50 ms–1
, largely ruling out a stellar companion and motivating
further observations with HARPS-N. From our HARPS-N radial-
velocity measurements outlined in subsection 2.2.2 and presented
in Appendix Table A2, we find that the data has an rms of only
2.60 ms–1
. From the peak-to-peak scatter in the RV observations, we
can place an upper limit on the companion mass of 10 M⊕, well
below the substellar limit. We also use TRICERATOPS (Giacalone
et al. 2021) to estimate the False Positive Probability (FPP) for Gliese
12 b. From TRICERATOPS we obtain a very low FPP of 5 × 10−4
.
(iii) The transit event is not caused by a background eclipsing
binary: We can preclude this scenario from archival imaging and high
proper motion of Gliese 12. In archival images of Gliese 12 taken by
DSS and 2MASS, we see no resolved sources in the TESS epoch sky
position of Gliese 12 within T 7.6 mag out to 25 arcsec (Fig. 4).
This is the minimum brightness difference required of an eclipsing
binary to generate an eclipse that can be diluted to our observed transit
depth of 1.1 ppt. We note that no sources exist in the Gaia Archive
(Gaia Collaboration et al. 2023) within 25 arcsec down to G mag 20.
Any resolvable sources within this radius would be too faint to cause
significant contamination in the transit photometry. In addition, our
high-resolution AO (subsection 2.3) reveals no companion sources
within K mag of 6.5 farther than 0.5 arcsec from Gliese 12. The
SPOC DV difference image centroid offset (Twicken et al. 2018)
locates the source of the transit signal within 9.9 ± 8.5 arcsec of
Gliese 12 and excludes all TIC objects within T mag of 7.6 as
potential transit sources.
(iv) Gliese 12 b does not host a widely separated companion that is
an eclipsing binary: If the flux from Gliese 12 were diluted by a bound
hierarchical companion, the spectra in subsection 2.2.2 would reveal
its presence unless it were smaller than Gliese 12. Our FPP estimate
with TRICERATOPS incorporates a computation of the probability
of this scenario (PEB and PEB×2P) from the shape of the transit
model. Our low FPP from TRICERATOPS therefore constrains this
scenario as well. Furthermore, our high-resolution AOs and speckle
imaging in subsection 2.3 reveal no companion sources down to K
mag = 13.8 at 0.2 arcsec. We can therefore confidently rule this
scenario out.
5 PLANET MODELLING
We model the transits of Gliese 12 b using the available photometry
from TESS, CHEOPS, MINERVA, and SPECULOOS. We first
obtain our prior on the stellar density ρ from Table 4 to apply to
our transit model.
Using the ensemble MCMC implemented in EMCEE (Foreman-
Mackey et al. 2013), we simultaneously model the transit and
apply least-squares detrending for the CHEOPS, MINERVA, and
SPECULOOS data. We use the transit model from Mandel Agol
(2002), implemented by Kreidberg (2015) in the BATMAN package,
supersampling by a factor of 2 for the TESS 20 s cadence data, by a
factor of 12 for the TESS 120 s cadence data, and by a factor of 4 for
all CHEOPS and ground-based data. We sample different quadratic
limb darkening coefficients for the different bandpasses of the
TESS, CHEOPS, MINERVA, SPECULOOS, and PMO photometry,
respectively. We obtain Gaussian prior means and standard deviations
on limb darkening coefficients from Claret (2017, 2021), using values
from Table 4 for Teff, log g, and metallicity. For the TESS, CHEOPS,
MINERVA, SPECULOOS, and PMO data we adopt TESS, CHEOPS,
full optical, and Sloan r’ filter bandpasses, respectively in order to
generate our prior.
We additionally used dynamic nested sampling through the
PyORBIT6
package (Malavolta et al. 2016, 2018), which uses
dynesty (Speagle 2020) to model planetary and stellar activity
signals and obtain best fit activity and planet parameters. PyORBIT
makes use of the BATMAN PYTHON package for fitting the transit to
the photometric data, where we assumed a quadratic stellar intensity
profile for fitting the limb darkening coefficients, and an exposure
time of 20.0 s for the TESS observations in sectors 42, 43, and 57,
120.0 s for TESS sector 70, 30.0 s for the CHEOPS observations,
30.0 and 60.0 s for the MINERVA telescopes 1 and 2 observations,
respectively, 10.0 s for the Europa, Ganymede, and Io SPECULOOS
observations, and 55.0 s for the PMO observations, as inputs to
the light-curve model. The priors placed on the limb-darkening
coefficients were calculated using interpolation from Claret (2017,
table 25) for the TESS light curves from Claret (2021, table 8) for
the CHEOPS light curves. For the EMCEE fit we apply Gaussian
priors on limb darkening, while for the dynesty fit we apply
these as uniform priors. This is because recent empirical constraints
have been in conflict with standard theoretical estimates of limb
darkening for cool stars (Patel Espinoza 2022). We therefore use
the PyORBIT model as confirmation that these potential problems
do not significantly impact our posterior estimates.
6https://github.com/LucaMalavolta/PyORBIT, version 8.
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Table 5. Planetary properties calculated from the combined transit fit. All limb darkening priors are normal for EMCEE and uniform for dynesty. We adopt
the EMCEE values due to the more conservative parameter uncertainty on Rp.
Parameter EMCEE dynesty Source
Fitted parameters
T0 (BJD) 2459497.184 ± 0.003 2459497.182+0.003
−0.002 Measured (uniform prior)
P (days) 12.76144 ± 0.00006 2.76142+0.00005
−0.00006 Measured (uniform prior)
Rp/R∗ 0.034 ± 0.002 0.031 ± 0.001 Measured (uniform prior)
b 0.80 ± 0.07 0.67+0.04
−0.05 Measured (uniform prior)
ρ∗ (g cm–3) 17.4 ± 0.6 7.4+1.3
−1.4 Measured (normal prior from Table 4)
a/R∗ 53.1 ± 0.6 53.4+1.5
−1.6 Measured (uniform prior)
Derived properties
Rp (R⊕) 1.03 ± 0.11 0.91 ± 0.04 Derived
i (degrees) 89.12 ± 0.07 89.28+0.06
−0.05 Derived
a (au) 0.066 ± 0.002 0.067 ± 0.003 Derived
Teq (K) 315 ± 5 315 ± 10 Derived (assuming AB = 0)
Teq (K) 287 ± 5 290 ± 9 Derived (assuming AB = A⊕)
F (S⊕) 1.6 ± 0.2 1.6 ± 0.2 Derived
Limb darkening coefficients
q1TESS 0.40 ± 0.20 0.60+0.27
−0.32 Measured (Claret (2017) prior)
q2TESS 0.12 ± 0.07 0.32+0.35
−0.23 Measured (Claret (2017) prior)
q1CHEOPS 0.60 ± 0.10 0.35+0.27
−0.22 Measured (Claret (2021) prior)
q2CHEOPS 0.17 ± 0.06 0.64+0.26
−0.38 Measured (Claret (2021) prior)
q1MINERVA 0.60 ± 0.10 0.60+0.27
−0.35 Measured
q2MINERVA 0.21 ± 0.06 0.53+0.32
−0.35 Measured
q1SPECULOOS 0.70 ± 0.20 0.71+0.21
−0.33 Measured
q2SPECULOOS 0.26 ± 0.07 0.61+0.28
−0.37 Measured
q1PMO 0.50 ± 0.20 0.53+0.32
−0.36 Measured
q2PMO 0.26 ± 0.07 0.51+0.33
−0.34 Measured
Inferred planetary parameters from the fit for both EMCEE and
dynesty are shown in Table 5, alongside the priors implemented.
We find that the results of the two methods are consistent to 1σ
across all planetary parameters. We note that a difference in errors
for our derived planetary radii is due to differences in our sampling
techniques’ tendencies to handle deviations from Gaussianity in our
posterior distributions. We adopt our final parameters from the model
with the more conservative parameter uncertainty on Rp, which is the
EMCEE fit. From this, we find Gliese 12 b to be a small, temperate
(1.0 ± 0.1 R⊕, 315 ± 5 K) planet with a 12.76144 ± 0.00006 d orbital
period. Fig. 5 shows the phase-folded light curves for the TESS,
CHEOPS, MINERVA, SPECULOOS, and PMO data along with the
best-fitting transit models using EMCEE sampling method. The phase-
folded light curves and best-fitting transit models obtained from the
dynesty sampling method for the data can be found in Fig. B1 of
Appendix B.
6 DISCUSSION
6.1 Prospects for mass measurement and interior composition
We use the results of the global photometric analysis (see Table 5)
to predict the expected planetary mass and radial velocity semi-
amplitude of the planet. Otegi, Bouchy Helled (2020) present a
mass–radius relation that is dependent on the density of the planet
(ρb):
Mb[M⊕] = (0.90 ± 0.06)Rb
(3.45±0.12)
if ρb 3.3gcm−3
. (1)
The high-density case is applicable when the planet has a rocky
composition, and assuming this, the planet would have a mass of
0.88+0.39
−0.26 M⊕, leading to a semi-amplitude of only 0.57+0.26
−0.17 ms−1
.
Given the brightness of the star, V (mag) = 12.600 ± 0.042, and
following the early observations from HARPS-N, the predicted pre-
cision on the RV measurements with continued HARPS-N observa-
tions is 1.15 ms−1
with a 30 min integration time. The planetary signal
should thus be detectable with sufficient observations taken with a
high-resolution high-stability spectrograph. Assuming a circular or-
bit and no correlated noise, we calculate that for a 3σ mass detection
approximately 200 HARPS-N RV observations would be needed,
with 30 min per observation, leading to a total of approximately
100 h of telescope time. For a 5σ mass detection, approximately
600 RV observations would be needed, leading to 300 h of telescope
time. Whilst these calculations are specific to HARPS-N, there are
other instruments capable of doing this, including those with better
stability such as ESPRESSO.
The above estimates might be slightly optimistic since they
ignore the possible impact of stellar activity. However, we highlight
that thanks to the low-activity level of Gliese 12, the expected
stellar-induced RV rms should only be 0.27+0.25
−0.14 ms–1
(using an
extrapolation of the relations in Hojjatpanah et al. (2020)). This
allows for the small planetary signal to be detectable in the data.
Additional planets in the system, including non-transiting ones, may
also be detectable through RV observations as multiplanet systems
are common for M-dwarfs, and compact multisystems are also more
common around low-metal stars (Anderson et al. 2021), such as
Gliese 12.
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Figure 5. Phased transits of Gliese 12 b from fit results obtained with EMCEE. The red lines represent the transit from the best fit MCMC model. The purple
data points are binned into 10 min intervals for TESS and CHEOPS and 11.5 min intervals for the ground-based data. The top left panel shows five phased TESS
transits, with the grey points representing the data binned down to 2 min cadence. The top right panel shows five phased CHEOPS transits of this target. The
bottom left panel shows the MINERVA-Australis data. The bottom-centre panel shows the SPECULOOS data, and the bottom right panel shows the PMO data.
With a measured mass and thus bulk density, the planet’s interior
structure can be studied. The density and internal structures of
Earth-like planets around metal-poor stars, such as Gliese 12 b,
is important as recent observational studies have found potential
compositional trends (Chen et al. 2022; Wilson et al. 2022) that may
be imprints of planet formation or evolution (Owen Jackson 2012;
Owen Murray-Clay 2018). Adibekyan et al. (2021) found that
planet density is correlated with stellar iron mass fraction for Earth-
like bodies, which provides evidence that the stellar compositional
environment affects planetary internal structure. Different interior
structure compositions due to formation environment variations
could impact potential habitability (Foley Driscoll 2016). Planets
around metal-poor stars may have small metallic cores and larger
mantles compared to Earth and thus have weaker magnetic fields
and increased volcanism. However, this is not well-understood as in
the low-metallicity regime this trend is only anchored by two well-
characterized planets (Mortier et al. 2020; Lacedelli et al. 2022), with
none as small or cold as Earth. Therefore, by combining our precise
radius measurement with an accurately measured mass of Gliese 12
b, we will be able to potentially verify a fundamental underlying
process sculpting small planets, including our own Earth, across the
galaxy.
6.2 Prospects for atmospheric characterization
Gliese 12 b is among the most amenable temperate (1.6 ± 0.2 S⊕),
terrestrial (1.0 ± 0.1 R⊕) planets for atmospheric spectroscopy
discovered to date. Its proximity to the Solar system (12 pc), high
apparent brightness (K = 7.8 mag), and relatively low-activity level
make it an ideal candidate for future transmission spectroscopy with
JWST. It is also unique in its parameter space for being exceptionally
bright yet temperate (Fig. 6), making it ideal for characterization.
So far, the TRAPPIST-1 system (Gillon et al. 2017) and the TOI-
700 system (Gilbert et al. 2020; Rodriguez et al. 2020; Gilbert
et al. 2023) have been the most well-studied exoplanet systems
harbouring Earth-sized, temperate planets (࣠500 K, ࣠ 1.6 R⊕). The
JWST emission spectrum of TRAPPIST-1c disfavours a thick CO2-
dominated atmosphere, although the presence of higher molecular
weight species cannot be constrained (Zieba et al. 2023). Other
temperate planets in the TRAPPIST-1 system are planned to be
targeted in JWST transmission and emission spectroscopy. The
Transmission Spectroscopy Metric (TSM; Kempton et al. (2018))
was created as a heuristic to assess the amenability of TESS planets to
transmission spectroscopy measurements. The TSM value of Gliese
12 b, using the mass–radius relation presented in equation (1) is
approximately 20. In comparison, the TRAPPIST-1 planets d, e, f, g,
and h present TSM values between 15 and 25. The TOI-700 system,
however, has been shown to be just out of the reach of JWST’s
capabilities (Suissa et al. 2020), with a TSM of less than 5. Gliese
12 is both closer, brighter, and lower activity than TRAPPIST-1 or
TOI-700, enabling uniquely constraining observations of its planet’s
atmosphere.
Just outside these equilibrium temperature and/or planetary radius
bounds, JWST transmission spectroscopy has returned mixed results
for atmospheric detection on different planets around M-dwarfs. LHS
475 b, though much hotter than Gliese 12 b, has been observed to have
a featureless spectrum by JWST so far (Lustig-Yaeger et al. 2023).
For the hot super-Earth GJ 486b, the JWST transmission spectrum
contains tantalizing features that may be interpreted either as a water
rich atmosphere or contamination from unocculted star-spots (Moran
et al. 2023).
Contamination from stellar activity represents an important noise
floor for detections of atmospheres around terrestrial planets, par-
ticularly for terrestrial planets around M-dwarfs (Rackham, Apai
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Figure 6. Gliese 12 is amongst the brightest stars (in K band) hosting a temperate Earth-sized planet. Only planets with radii between 0.7 and 1.6 R⊕ and
insolation flux between 0.1 and 10 S⊕ on the Exoplanet Archive as of 2024 January 03 are shown in the figure. The star represents Gliese 12 b and other notable
Earth-sized planets are labeled. The TRAPPIST-1 planets in order from left to right are b, c, d, e, f, g, and h.
Giampapa 2018). Most M-dwarfs and many other stars present non-
uniform stellar photospheres due to the presence of large spots. These
spots typically introduce photometric variability on a scale greater
than 1 per cent of the total stellar flux. For these stars, unocculted
spots introduce positive features in transmission spectra, which
can mimic signatures due to molecular absorption in the planet’s
atmosphere (e.g. Moran et al. 2023). This problem has been noted
recently with JWST in efforts to constrain temperate, terrestrial planet
atmospheres for the TRAPPIST-1 system (Lim et al. 2023). Gliese
12 is well monitored by both ground-based photometry and spec-
troscopy, showing a low-activity level for M-dwarfs and slow rotation
in comparison to the Mignon et al. (2023) sample which featured
only 7 stars with a lower log R
HK (subsection 3.3). Compared to the
other similar systems, such as TOI-700 and TRAPPIST-1, the lack
of visible star-spot variability in the light curves, very low magnetic
activity indicators, and slow rotation means that contamination in the
planetary spectra from stellar spots will likely be far lower, making
any interpretation of spectra features more tractable.
Whilst no high-molecular weight atmosphere has yet been detected
on such a planet, the atmospheres of Venus and the Earth in the Solar
system hint at the possible diversity of such atmospheres elsewhere.
M-dwarfs are the most numerous stellar type in our galaxy, and
terrestrial planets around them are commonplace (Dressing Char-
bonneau 2015). The atmospheric compositions of true solar system
analogues will be inaccessible for the foreseeable future. Therefore,
studies of cool, rocky planets around M-dwarfs – similar in insolation
and mass to Earth and Venus – will provide insight into the formation
of our Solar system and the diverse atmospheres of the terrestrial
planets. H2O, CO2, and CH4 features in the atmospheres of such
planets would also be accessible to JWST (Wunderlich et al. 2019).
A key question in the study of the habitability of planets around
M-dwarfs is these planets’ capacity to retain an atmosphere in the
face of high-stellar activity. Due to high XUV flux and flares from
the stars, it has been hypothesized that the planetary atmospheres
are photoevaporated efficiently, even for temperate planets (e.g.
Zahnle Catling 2017; Lincowski et al. 2018). The degree and extent
to which this occurs is still poorly understood. JWST atmospheric
studies of Gliese 12 b therefore presents a valuable opportunity to
make constraining measurements of a temperate, terrestrial planet’s
atmosphere, towards understanding the requisites of habitability for
planets around M-dwarfs.
6.3 Prospects for habitability
As the closest temperate, Earth-sized transiting planet to the Solar
system, a key open question is the potential for Gliese 12 b to maintain
temperatures suitable for liquid water to exist on its surface. With
an insolation between the Earth and Venus’s (F = 1.6 ± 0.2 S⊕),
this planet’s surface temperature would be highly dependant on its
atmospheric conditions. It is also unknown whether Gliese 12 b
is tide-locked or exists in a spin-orbit resonance, which may also
impact the retention of water in the planet’s evolutionary history
(Pierrehumbert Hammond 2019). Gliese 12 b occurs just inward
of the habitable zone as defined by Kopparapu et al. (2013) due to
the predicted efficiency of water-loss around M-dwarfs. However,
Gliese 12 b may well be within the recent Venus limit of its host star
(Fig. 7) with an insolation flux of F = 1.6 ± 0.2 S⊕, less than 1σ away
from the 1.5 S⊕ limit calculated from Kopparapu et al. (2013). This
limit is regarded in that analysis as an optimistic habitable zone due
to Venus’s potential for habitability in the past history of the Solar
system. Thus the available evidence does not rule out that Gliese 12
b is potentially habitable.
Due to its proximity to the recent Venus limit, this target may be
a valuable calibration point for theoretical estimates of water-loss,
which define the inner edge of the habitable zone. In particular, Gliese
12 b is well-suited to study the divergent evolutionary pathways
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Figure 7. Planetary radius versus distance, insolation, and stellar radius, respectively. Planets were taken from the Extrasolar Planets Encyclopaedia, with those
orbiting M-dwarfs highlighted as pink squares, and the rest shown as grey circles. Gliese 12 b is highlighted by the white star in the purple square. The orange
hexagons correspond to the TRAPPIST-1 planets; nearby planets around small stars that are most accessible to characterization by the JWST. The green-shaded
region in B is the M-dwarf habitable zone, the black-dashed line corresponds to a run-away greenhouse atmosphere, and the dark red-dashed line corresponds to
recent Venus (Kopparapu et al. 2013). We note that this habitable zone is only appropriate for planets orbiting M-dwarfs. The size of each marker is proportional
to the transit depth and hence observational accessibility.
of the atmospheres of Earth and Venus. While Earth retained its
water, the runaway greenhouse effect on Venus led to water escape
and photodissociation (Ingersoll 1969). If a runaway greenhouse
effect is in progress, signatures may be detectable in the UV-band as
an extended hydrogen exosphere (Bourrier et al. 2017a, b). A null
detection of water could hint that such a process has already occurred,
as on Venus. Alternatively, a detection of water would imply that the
water-loss boundary is inward of the estimates by Kopparapu et al.
(2013).
7 CONCLUSIONS
In this paper, we have reported on the discovery and validation
of a temperate Earth-sized planet transiting the nearby M-dwarf
Gliese 12. During TESS sectors 43, 57, only 3 transits of the
planet were observed, with no transits observed in sector 42. This
allowed for a period of 12.76 or 25.5 d, but with the further
addition of TESS sector 70 and CHEOPS follow-up we were
able to determine the actual period. Combining these transits with
further ground-based photometry from MINERVA, SPECULOOS,
and PMO allowed us to determine precise planetary parameters
for Gliese 12 b, indicating that Gliese 12 b is a 1.0 ± 0.1 R⊕
planet with a 12.76144 ± 0.00006 d period, and an effective
temperature lower than that of the majority of known exoplanets
(∼315 K).
Gliese 12 b is therefore a prime target for future detailed charac-
terization studies. Its prospects for a precise mass measurement are
reasonable and the star has some of the lowest activity levels amongst
known M-dwarfs. It is also a unique candidate for both atmospheric
and stellar study. Further analysis of the Gliese 12 system will allow
us to understand evolutionary and compositional trends, which is
important as we try to infer the number of true-Earth analogues on
our journey to understanding our own place in the universe.
ACKNOWLEDGEMENTS
CXH and AV are supported by ARC DECRA project DE200101840.
VVE is supported by UK’s Science Technology Facilities Council
(STFC) through the STFC grants ST/W001136/1 and ST/S000216/1.
This paper includes data collected by the TESS mission, which are
publicly available from the Mikulski Archive for Space Telescopes
(MAST). Funding for the TESS mission is provided by NASA’s
Science Mission directorate. We acknowledge the use of public
TESS Alert data from pipelines at the TESS Science Office and at
the TESS SPOC. Resources supporting this work were provided
by the NASA High-End Computing (HEC) Programme through
the NASA Advanced Supercomputing (NAS) Division at Ames
Research Centre for the production of the SPOC data products.
This work makes use of data from the European Space Agency
(ESA) CHEOPS mission, acquired through the CHEOPS AO-4
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Guest Observers Programmes ID:07 (PI: Palethorpe) and ID:12
(PI: Venner). CHEOPS is an ESA mission in partnership with
Switzerland with important contributions to the payload and the
ground segment from Austria, Belgium, France, Germany, Hungary,
Italy, Portugal, Spain, Sweden, and the United Kingdom. We thank
support from the CHEOPS GO Programme and Science Operations
Centre for help in the preparation and analysis of the CHEOPS
observations. This research has made use of the Exoplanet Follow-
up Observation Programme (ExoFOP) website, which is operated
by the California Institute of Technology, under contract with the
National Aeronautics and Space Administration under the Exoplanet
Exploration Programme.
This work makes use of data from MINERVA-Australis.
MINERVA-Australis is supported by Australian Research Council
LIEF Grant number LE160100001, Discovery Grants DP180100972
and DP220100365, Mount Cuba Astronomical Foundation, and insti-
tutional partners University of Southern Queensland, UNSW Sydney,
MIT, Nanjing University, George Mason University, University of
Louisville, University of California Riverside, University of Florida,
and The University of Texas at Austin. We acknowledge and pay
respect to Australia’s Aboriginal and Torres Strait Islander peoples,
who are the traditional custodians of the lands, waterways, and skies
all across Australia. In particular, we pay our deepest respects to
all Elders, ancestors, and descendants of the Giabal, Jarowair, and
Yuggera nations, upon whose lands the MINERVA-Australis facility
is situated.
We thank Ye Yuan and Jian Chen for their assistance in obtaining
and reducing the PMO photometry data.
Based on data collected by the SPECULOOS-South Observatory
at the ESO Paranal Observatory in Chile. The ULiege’s contri-
bution to SPECULOOS has received funding from the European
Research Council under the European Union’s Seventh Framework
Programme (FP/2007-2013) (grant Agreement no. 336480/SPECU-
LOOS), from the Balzan Prize and Francqui Foundations, from
the Belgian Scientific Research Foundation (F.R.S.-FNRS; grant
no. T.0109.20), from the University of Liege, and from the ARC
grant for Concerted Research Actions financed by the Wallonia-
Brussels Federation. This work is supported by a grant from the
Simons Foundation (PI Queloz, grant no. 327127). This research is
in part funded by the European Union’s Horizon 2020 research and
innovation programme (grants agreements no. 803193/BEBOP), and
from the Science and Technology Facilities Council (STFC; grant
no. ST/S00193X/1 and ST/W000385/1). The material is based upon
work supported by NASA under award number 80GSFC21M0002.
This publication benefits from the support of the French Community
of Belgium in the context of the FRIA Doctoral Grant awarded to MT.
This publication benefits from the support of the French Community
of Belgium in the context of the FRIA Doctoral Grant awarded
to MT.
Some of the data presented herein were obtained at Keck Observa-
tory, which is a private 501(c)3 non-profit organization operated as a
scientific partnership among the California Institute of Technology,
the University of California, and the National Aeronautics and Space
Administration. The Observatory was made possible by the generous
financial support of the W. M. Keck Foundation. The authors wish
to recognize and acknowledge the very significant cultural role and
reverence that the summit of Maunakea has always had within the
Native Hawaiian community. We are most fortunate to have the
opportunity to conduct observations from this mountain.
The HARPS-N project was funded by the Prodex Programme of
the Swiss Space Office (SSO), the Harvard University Origin of
Life Initiative (HUOLI), the Scottish Universities Physics Alliance
(SUPA), the University of Geneva, the Smithsonian Astrophysical
Observatory (SAO), the Italian National Astrophysical Institute
(INAF), University of St. Andrews, Queen’s University Belfast, and
University of Edinburgh.
This work has made use of data from the European Space Agency
(ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed
by the Gaia Data Processing and Analysis Consortium (DPAC, https:
//www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the
DPAC has been provided by national institutions, in particular
the institutions participating in the Gaia Multilateral Agreement.
This research has made use of the SIMBAD data base and VizieR
catalogue access tool, operated at CDS, Strasbourg, France. This
research has made use of NASA’s Astrophysics Data System. This
research has made use of the NASA Exoplanet Archive, which is
operated by the California Institute of Technology, under contract
with the National Aeronautics and Space Administration under the
Exoplanet Exploration Programme.
This research has made use of the Exoplanet Follow-up Obser-
vation Programme (ExoFOP; DOI: 10.26134/ExoFOP5) website,
which is operated by the California Institute of Technology, under
contract with the National Aeronautics and Space Administration
under the Exoplanet Exploration Programme.
This research is based on photographic data obtained using Oschin
Schmidt Telescope on Palomar Mountain. The Palomar Observatory
Sky Survey was funded by the National Geographic Society. The
Oschin Shmidt Telescope is operated by the California Institue of
Technology and Palomar Observatory. The plates were processed
into the present compressed digital format with their permission.
The Digitized Sky Survey was produced at the Space Telescope
Science Institute (ST ScI) under US Goverment grant number NAG
W-2166.
LD thanks the Belgian Federal Science Policy Office (BELSPO)
for the provision of financial support in the framework of the
PRODEX Programme of the European Space Agency (ESA) under
contract number 4000142531.
KR is grateful for support from UK’s Science and Technol-
ogy Facilities Council (STFC) via consolidated grant number
ST/V000594/1.
DAT acknowledges the support of the Science and Technology
Facilities Council (STFC).
The ULiege’s contribution to SPECULOOS has received funding
from the European Research Council under the European Union’s
Seventh Framework Programme (FP/2007-2013) (grant Agreement
no. 336480/SPECULOOS), from the Balzan Prize and Francqui
Foundations, from the Belgian Scientific Research Foundation
(F.R.S.-FNRS; grant no. T.0109.20), from the University of Liege,
and from the ARC grant for Concerted Research Actions financed
by the Wallonia-Brussels Federation. MG is F.R.S-FNRS Research
Director.
This research has made use of data obtained from or tools provided
by the portal exoplanet.eu of The Extrasolar Planets Encyclopaedia.
DATA AVAILABILITY
This paper includes raw data collected by the TESS mission, which
are publicly available from the Mikulski Archive for Space Tele-
scopes (MAST, https://archive.stsci.edu/tess). Raw data collected by
CHEOPS can be found using the file keys in Table 1 at https://cheo
ps-archive.astro.unige.ch/archive browser/. Observations made with
HARPS-N on the TNG 3.6 m telescope are available in Table A2 in
the Appendix Section A. Observations made with TRES are available
in Table A1 also in Appendix Section A.
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APPENDIX A: RV DATA
Table A1. TRES radial velocity data and activity indicators.
BJDUTC RV σRV pha Teff σTeff Vrot σVrot CCF SNRe
(d) (m s−1) (m s−1)
2457674.500000 51286 21 −71.41 0.0 0.0 0.0 0.5 0.931 20.1
2457920.500000 51308 21 −61.76 0.0 0.0 0.8 0.5 0.940 23.5
2458654.500000 51279 21 −33.00 0.0 0.0 1.9 0.5 0.915 16.2
2459468.500000 51256 21 −1.11 0.0 0.0 1.5 0.5 0.947 23.3
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Figure B1. Phased transits of Gliese 12 b from fit results obtained with dynesty. Transit fit to the light-curve data from TESS (top left), CHEOPS (top
right), MINERVA (bottom left), SPECULOOS (bottom), and PMO (bottom right). The short cadence (20 s for TESS sectors 42, 43, and 57, 120 s for TESS
sector 70, 30 s for CHEOPS, 10 s for all SPECULOOS telescopes, 30 s for MINERVA T1, 60 s for MINERVA T2, and 55 s for PMO) fluxes are plotted in grey,
the binned fluxes are overplotted in purple (10 min for space-based data and 11.5 min for ground-based data), and the fitted transit is shown by the red solid
line.
1University of Southern Queensland, Centre for Astrophysics, West Street,
Toowoomba, QLD 4350, Australia
2SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill,
Edinburgh, EH9 3HJ, UK
3Centre for Exoplanet Science, University of Edinburgh, Edinburgh, EH9
3HJ, UK
4Mullard Space Science Laboratory, University College London , Holmbury
St Mary, Dorking, Surrey, RH5 6NT, UK
5School of Physics and Astronomy, University of Birmingham, Edgbaston,
Birmingham B15 2TT, UK
6Department of Physics, University of Warwick, Gibbet Hill Road, Coventry
CV4 7AL, UK
7Centre for Exoplanets and Habitability, University of Warwick, Coventry
CV4 7AL, UK
8Department of Physics Astronomy, McMaster University, 1280 Main
Street W, Hamilton, ON L8S 4L8, Canada
9Fundación Galileo Galilei - INAF (Telescopio Nazionale Galileo), Rambla
José Ana Fernández Perez 7, E-38712 Bre˜
na Baja (La Palma), Canary
Islands, Spain
10Instituto de Astrofı́sica de Canarias, C/Vı́a Láctea s/n, E-38205 La Laguna
(Tenerife), Canary Islands, Spain
11Departamento de Astrofı́sica, Univ. de La Laguna, Av. del Astrofı́sico
Francisco Sánchez s/n, E-38205 La Laguna (Tenerife), Canary Islands,
Spain
12NASA Exoplanet Science Institute, IPAC, California Institute of Technology,
Pasadena, CA 91125 USA
13Astrobiology Research Unit, University of Liège, Allée du 6 aoˆ
ut, 19, B-
4000 Liège (Sart-Tilman), Belgium
14Space Sciences, Technologies and Astrophysics Research (STAR) Institute,
Université de Liège, Allée du 6 Aoˆ
ut 19C, B-4000 Liège, Belgium
15Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven,
Belgium
16AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris, F-91191
Gif-sur-Yvette, France
17Department of Physics and Astronomy, The University of New Mexico, 210
Yale Blvd NE, Albuquerque, NM 87106, USA
18NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 N.
Cherry Ave., Tucson, AZ 85719, USA
19Astrobiology Research Unit, Université de Liège, Allée du 6 Aoˆ
ut 19C,
B-4000 Liège, Belgium
20Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
21Department of Physics and Kavli Institute for Astrophysics and Space
Research, Massachusetts Institute of Technology, Cambridge, MA 02139,
USA
22Center for Astrophysics | Harvard Smithsonian, 60 Garden Street,
Cambridge, MA 02138, USA
23CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory,
Chinese Academy of Sciences, Nanjing 210008, China
24Proto-Logic Consulting LLC, Washington, DC, USA
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