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.
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.
The Variable Detection of Atmospheric Escape around the Young, Hot Neptune AU...Sérgio Sacani
This document summarizes observations from the Hubble Space Telescope of the young hot Neptune exoplanet AU Mic b, which orbits the nearby M dwarf star AU Mic. The observations aimed to detect atmospheric escape of neutral hydrogen through absorption in the stellar Lyman-alpha emission line. Two visits were obtained, one in 2020 and one in 2021, corresponding to transits of the planet. A stellar flare was observed and removed from the first visit data. In the second visit, absorption was detected in the blue wing of the Lyman-alpha line 2.5 hours before the white light transit, indicating the presence of high-velocity neutral hydrogen escaping the planet's atmosphere and traveling toward the observer. Estimates place the column density of this material
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.
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.
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.
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.
The Variable Detection of Atmospheric Escape around the Young, Hot Neptune AU...Sérgio Sacani
This document summarizes observations from the Hubble Space Telescope of the young hot Neptune exoplanet AU Mic b, which orbits the nearby M dwarf star AU Mic. The observations aimed to detect atmospheric escape of neutral hydrogen through absorption in the stellar Lyman-alpha emission line. Two visits were obtained, one in 2020 and one in 2021, corresponding to transits of the planet. A stellar flare was observed and removed from the first visit data. In the second visit, absorption was detected in the blue wing of the Lyman-alpha line 2.5 hours before the white light transit, indicating the presence of high-velocity neutral hydrogen escaping the planet's atmosphere and traveling toward the observer. Estimates place the column density of this material
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.
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.
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.
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.
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 transit method detects exoplanets by observing periodic dips in a star's light caused by planets passing in front of the star. This method has discovered over 80% of known exoplanets. It allows determining planet properties like radius, atmosphere composition by analyzing light passing through. The Kepler space telescope extensively uses this method to study exoplanet candidates.
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.
Beyond the Drake Equation: A Time-Dependent Inventory of Habitable Planets an...Sérgio Sacani
We introduce a mathematical framework for statistical exoplanet population and astrobiology studies
that may help directing future observational efforts and experiments. The approach is based on a
set of differential equations and provides a time-dependent mapping between star formation, metal
enrichment, and the occurrence of exoplanets and potentially life-harboring worlds over the chemopopulation history of the solar neighborhood. Our results are summarized as follows: 1) the formation
of exoplanets in the solar vicinity was episodic, starting with the emergence of the thick disk about
11 Gyr ago; 2) within 100 pc from the Sun, there are as many as 11, 000 (η⊕/0.24) Earth-size planets
in the habitable zone (“temperate terrestrial planets” or TTPs) of K-type stars. The solar system is
younger than the median TTP, and was created in a star formation surge that peaked 5.5 Gyr ago and
was triggered by an external agent; 3) the metallicity modulation of the giant planet occurrence rate
results in a later typical formation time, with TTPs outnumbering giant planets at early times; 4) the
closest, life-harboring Earth-like planet would be ∼
< 20 pc away if microbial life arose as soon as it did
on Earth in ∼
> 1% of the TTPs around K stars. If simple life is abundant (fast abiogenesis), it is also
old, as it would have emerged more than 8 Gyr ago in about one third of all life-bearing planets today.
Older Earth analogs are more likely to have developed sufficiently complex life capable of altering the
environment and producing detectable oxygenic biosignatures.
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
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.
The ExoplanetSat Mission to Detect Transiting Exoplanets with a CShawn Murphy
1) ExoplanetSat is a CubeSat mission that aims to detect Earth-sized exoplanets transiting nearby bright stars using ultra-precise photometry.
2) It will monitor individual target stars to detect the characteristic dip in light level caused by a transiting exoplanet. Any planets detected could then be studied by larger telescopes to characterize their atmospheres.
3) ExoplanetSat's design incorporates a 6cm telescope combined with a fine image stabilization system to achieve near shot-noise limited photometry, allowing detection of Earth-sized planets transiting stars as bright as magnitude 6.
An Earth-sized exoplanet with a Mercury-like compositionSérgio Sacani
Earth, Venus, Mars and some extrasolar terrestrial planets1
have a mass and radius that is consistent with a mass fraction
of about 30% metallic core and 70% silicate mantle2
. At the
inner frontier of the Solar System, Mercury has a completely
different composition, with a mass fraction of about 70%
metallic core and 30% silicate mantle3
. Several formation or
evolution scenarios are proposed to explain this metal-rich
composition, such as a giant impact4, mantle evaporation5
or the depletion of silicate at the inner edge of the protoplanetary
disk6. These scenarios are still strongly debated.
Here, we report the discovery of a multiple transiting planetary
system (K2-229) in which the inner planet has a radius
of 1.165 ± 0.066 Earth radii and a mass of 2.59 ± 0.43 Earth
masses. This Earth-sized planet thus has a core-mass fraction
that is compatible with that of Mercury, although it was
expected to be similar to that of Earth based on host-star
chemistry7
. This larger Mercury analogue either formed with
a very peculiar composition or has evolved, for example, by
losing part of its mantle. Further characterization of Mercurylike
exoplanets such as K2-229 b will help to put the detailed
in situ observations of Mercury (with MESSENGER and
BepiColombo8) into the global context of the formation and
evolution of solar and extrasolar terrestrial planets.
This document presents an analysis of transit spectroscopy observations of three exoplanets - WASP-12 b, WASP-17 b, and WASP-19 b - using the Wide Field Camera 3 instrument on the Hubble Space Telescope. The observations achieved almost photon-limited precision but uncertainties in the transit depths were increased by the uneven sampling of the light curves. The final transit spectra for all three planets are consistent with the presence of a water absorption feature at 1.4 microns, though the amplitude is smaller than expected from previous Spitzer observations possibly due to hazes. Due to degeneracies between models, the data cannot unambiguously constrain the atmospheric compositions without additional observations.
Detection of an atmosphere around the super earth 55 cancri eSérgio Sacani
We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near
infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent
star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness
of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length
and a very high scanning speed. We use our specialized pipeline to take into account systematics
introduced by these observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average relative uncertainty
of 22 ppm per visit and nd modulations that depart from a straight line model with a 6 condence
level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T -REx, has identied HCN to be the
most likely molecular candidate able to explain the features at 1.42 and 1.54 m. While additional
spectroscopic observations in a broader wavelength range in the infrared will be needed to conrm
the HCN detection, we discuss here the implications of such result. Our chemical model, developed
with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a
high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic
than previously thought.
Kinematics and simulations_of_the_stellar_stream_in_the_halo_of_the_umbrella_...Sérgio Sacani
This document summarizes a study of the stellar stream and substructures around the Umbrella Galaxy (NGC 4651). Deep imaging and spectroscopy were used to characterize the properties and kinematics of the stream. Tracer objects like globular clusters and planetary nebulae were identified and found to delineate a kinematically cold feature in position-velocity space. Dynamical modeling suggests the stream originated from the tidal disruption of a dwarf galaxy on a highly eccentric orbit about 6-10 billion years ago. This work demonstrates the feasibility of using discrete tracers to recover the kinematics and model the dynamics of low surface brightness stellar streams around distant galaxies.
Transit photometry has been the most successful exoplanet discovery method to date. It works by detecting the dimming of a star's light as a planet passes in front of it. From the transit light curve, properties of the planet like its radius and orbital parameters can be derived. However, transits have a low probability of being aligned with our line of sight. False positives from eclipsing binaries can also mimic transits, so follow-up observations are needed to confirm planetary discoveries. Past and current transit surveys have found over a hundred planets, and future surveys aim to detect smaller planets orbiting brighter stars.
A dynamically packed_planetary _system_around_gj667_c_with_three_superearths_...Sérgio Sacani
This document summarizes the discovery of six potentially habitable super-Earth planets orbiting the red dwarf star GJ 667C. Analyzing new Doppler measurements from HARPS and previous data from other spectrographs, the authors detect six planetary candidates with orbital periods of 7, 28, 92, 62, 39, and 260 days. They validate the signals against stellar activity and find the system could be dynamically stable. Three or four of the planets may be located within the star's habitable zone where liquid water could exist, making this one of the first exoplanetary systems discovered with multiple Earth-sized planets in the habitable zone of an M-dwarf star.
This document summarizes an 8-year survey using the HARPS spectrograph to detect super-Earth and Neptune-mass planets around solar-type stars. Over 50% of solar-type stars were found to harbor at least one planet within 100 days. The mass distribution of super-Earths and Neptune-mass planets increases sharply from 30-15 Earth masses. Most of these planets belong to multi-planetary systems and have orbital eccentricities under 0.45. In contrast, giant planets are more common around metal-rich stars and can have eccentricities over 0.9. The precision of HARPS enables detection of planets in the habitable zones of solar-type stars.
This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet
Third epoch magellanic_clouud_proper_motionsSérgio Sacani
The document analyzes proper motion data from the Hubble Space Telescope to study the three-dimensional rotation field of the Large Magellanic Cloud (LMC) galaxy. It finds that:
1) The proper motion data implies a stellar dynamical center that coincides with the HI dynamical center from previous studies.
2) Combining the proper motion and line-of-sight velocity data provides insights into the LMC's rotation curve, disk viewing angles, and circular rotation speed of 91.7 km/s outside the central region.
3) The data paint a consistent picture of LMC rotation and yield improved constraints on the galaxy's distance, mass profile, and orbital history around the Milky Way.
This document summarizes evidence that submillimeter galaxies (SMGs) at redshift 3-6 may be progenitors of compact quiescent galaxies observed at redshift 2. It compares properties of a sample of z~2 quiescent galaxies with a statistical sample of z>3 SMGs in the COSMOS field. It finds that the formation redshifts of the z~2 galaxies match the observed redshift distribution of z>3 SMGs. It also finds that the space densities and properties such as sizes, stellar masses, and internal velocities of the two populations are consistent with an evolutionary connection, assuming SMG starbursts have a duty cycle of 42+40 Myr. This suggests SMGs may represent an early burst
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
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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.
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 transit method detects exoplanets by observing periodic dips in a star's light caused by planets passing in front of the star. This method has discovered over 80% of known exoplanets. It allows determining planet properties like radius, atmosphere composition by analyzing light passing through. The Kepler space telescope extensively uses this method to study exoplanet candidates.
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.
Beyond the Drake Equation: A Time-Dependent Inventory of Habitable Planets an...Sérgio Sacani
We introduce a mathematical framework for statistical exoplanet population and astrobiology studies
that may help directing future observational efforts and experiments. The approach is based on a
set of differential equations and provides a time-dependent mapping between star formation, metal
enrichment, and the occurrence of exoplanets and potentially life-harboring worlds over the chemopopulation history of the solar neighborhood. Our results are summarized as follows: 1) the formation
of exoplanets in the solar vicinity was episodic, starting with the emergence of the thick disk about
11 Gyr ago; 2) within 100 pc from the Sun, there are as many as 11, 000 (η⊕/0.24) Earth-size planets
in the habitable zone (“temperate terrestrial planets” or TTPs) of K-type stars. The solar system is
younger than the median TTP, and was created in a star formation surge that peaked 5.5 Gyr ago and
was triggered by an external agent; 3) the metallicity modulation of the giant planet occurrence rate
results in a later typical formation time, with TTPs outnumbering giant planets at early times; 4) the
closest, life-harboring Earth-like planet would be ∼
< 20 pc away if microbial life arose as soon as it did
on Earth in ∼
> 1% of the TTPs around K stars. If simple life is abundant (fast abiogenesis), it is also
old, as it would have emerged more than 8 Gyr ago in about one third of all life-bearing planets today.
Older Earth analogs are more likely to have developed sufficiently complex life capable of altering the
environment and producing detectable oxygenic biosignatures.
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
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.
The ExoplanetSat Mission to Detect Transiting Exoplanets with a CShawn Murphy
1) ExoplanetSat is a CubeSat mission that aims to detect Earth-sized exoplanets transiting nearby bright stars using ultra-precise photometry.
2) It will monitor individual target stars to detect the characteristic dip in light level caused by a transiting exoplanet. Any planets detected could then be studied by larger telescopes to characterize their atmospheres.
3) ExoplanetSat's design incorporates a 6cm telescope combined with a fine image stabilization system to achieve near shot-noise limited photometry, allowing detection of Earth-sized planets transiting stars as bright as magnitude 6.
An Earth-sized exoplanet with a Mercury-like compositionSérgio Sacani
Earth, Venus, Mars and some extrasolar terrestrial planets1
have a mass and radius that is consistent with a mass fraction
of about 30% metallic core and 70% silicate mantle2
. At the
inner frontier of the Solar System, Mercury has a completely
different composition, with a mass fraction of about 70%
metallic core and 30% silicate mantle3
. Several formation or
evolution scenarios are proposed to explain this metal-rich
composition, such as a giant impact4, mantle evaporation5
or the depletion of silicate at the inner edge of the protoplanetary
disk6. These scenarios are still strongly debated.
Here, we report the discovery of a multiple transiting planetary
system (K2-229) in which the inner planet has a radius
of 1.165 ± 0.066 Earth radii and a mass of 2.59 ± 0.43 Earth
masses. This Earth-sized planet thus has a core-mass fraction
that is compatible with that of Mercury, although it was
expected to be similar to that of Earth based on host-star
chemistry7
. This larger Mercury analogue either formed with
a very peculiar composition or has evolved, for example, by
losing part of its mantle. Further characterization of Mercurylike
exoplanets such as K2-229 b will help to put the detailed
in situ observations of Mercury (with MESSENGER and
BepiColombo8) into the global context of the formation and
evolution of solar and extrasolar terrestrial planets.
This document presents an analysis of transit spectroscopy observations of three exoplanets - WASP-12 b, WASP-17 b, and WASP-19 b - using the Wide Field Camera 3 instrument on the Hubble Space Telescope. The observations achieved almost photon-limited precision but uncertainties in the transit depths were increased by the uneven sampling of the light curves. The final transit spectra for all three planets are consistent with the presence of a water absorption feature at 1.4 microns, though the amplitude is smaller than expected from previous Spitzer observations possibly due to hazes. Due to degeneracies between models, the data cannot unambiguously constrain the atmospheric compositions without additional observations.
Detection of an atmosphere around the super earth 55 cancri eSérgio Sacani
We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near
infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent
star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness
of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length
and a very high scanning speed. We use our specialized pipeline to take into account systematics
introduced by these observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average relative uncertainty
of 22 ppm per visit and nd modulations that depart from a straight line model with a 6 condence
level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T -REx, has identied HCN to be the
most likely molecular candidate able to explain the features at 1.42 and 1.54 m. While additional
spectroscopic observations in a broader wavelength range in the infrared will be needed to conrm
the HCN detection, we discuss here the implications of such result. Our chemical model, developed
with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a
high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic
than previously thought.
Kinematics and simulations_of_the_stellar_stream_in_the_halo_of_the_umbrella_...Sérgio Sacani
This document summarizes a study of the stellar stream and substructures around the Umbrella Galaxy (NGC 4651). Deep imaging and spectroscopy were used to characterize the properties and kinematics of the stream. Tracer objects like globular clusters and planetary nebulae were identified and found to delineate a kinematically cold feature in position-velocity space. Dynamical modeling suggests the stream originated from the tidal disruption of a dwarf galaxy on a highly eccentric orbit about 6-10 billion years ago. This work demonstrates the feasibility of using discrete tracers to recover the kinematics and model the dynamics of low surface brightness stellar streams around distant galaxies.
Transit photometry has been the most successful exoplanet discovery method to date. It works by detecting the dimming of a star's light as a planet passes in front of it. From the transit light curve, properties of the planet like its radius and orbital parameters can be derived. However, transits have a low probability of being aligned with our line of sight. False positives from eclipsing binaries can also mimic transits, so follow-up observations are needed to confirm planetary discoveries. Past and current transit surveys have found over a hundred planets, and future surveys aim to detect smaller planets orbiting brighter stars.
A dynamically packed_planetary _system_around_gj667_c_with_three_superearths_...Sérgio Sacani
This document summarizes the discovery of six potentially habitable super-Earth planets orbiting the red dwarf star GJ 667C. Analyzing new Doppler measurements from HARPS and previous data from other spectrographs, the authors detect six planetary candidates with orbital periods of 7, 28, 92, 62, 39, and 260 days. They validate the signals against stellar activity and find the system could be dynamically stable. Three or four of the planets may be located within the star's habitable zone where liquid water could exist, making this one of the first exoplanetary systems discovered with multiple Earth-sized planets in the habitable zone of an M-dwarf star.
This document summarizes an 8-year survey using the HARPS spectrograph to detect super-Earth and Neptune-mass planets around solar-type stars. Over 50% of solar-type stars were found to harbor at least one planet within 100 days. The mass distribution of super-Earths and Neptune-mass planets increases sharply from 30-15 Earth masses. Most of these planets belong to multi-planetary systems and have orbital eccentricities under 0.45. In contrast, giant planets are more common around metal-rich stars and can have eccentricities over 0.9. The precision of HARPS enables detection of planets in the habitable zones of solar-type stars.
This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet
Third epoch magellanic_clouud_proper_motionsSérgio Sacani
The document analyzes proper motion data from the Hubble Space Telescope to study the three-dimensional rotation field of the Large Magellanic Cloud (LMC) galaxy. It finds that:
1) The proper motion data implies a stellar dynamical center that coincides with the HI dynamical center from previous studies.
2) Combining the proper motion and line-of-sight velocity data provides insights into the LMC's rotation curve, disk viewing angles, and circular rotation speed of 91.7 km/s outside the central region.
3) The data paint a consistent picture of LMC rotation and yield improved constraints on the galaxy's distance, mass profile, and orbital history around the Milky Way.
This document summarizes evidence that submillimeter galaxies (SMGs) at redshift 3-6 may be progenitors of compact quiescent galaxies observed at redshift 2. It compares properties of a sample of z~2 quiescent galaxies with a statistical sample of z>3 SMGs in the COSMOS field. It finds that the formation redshifts of the z~2 galaxies match the observed redshift distribution of z>3 SMGs. It also finds that the space densities and properties such as sizes, stellar masses, and internal velocities of the two populations are consistent with an evolutionary connection, assuming SMG starbursts have a duty cycle of 42+40 Myr. This suggests SMGs may represent an early burst
Similar to TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS and HARPS (20)
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
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.
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.
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Creative-Biolabs
Neutralizing antibodies, pivotal in immune defense, specifically bind and inhibit viral pathogens, thereby playing a crucial role in protecting against and mitigating infectious diseases. In this slide, we will introduce what antibodies and neutralizing antibodies are, the production and regulation of neutralizing antibodies, their mechanisms of action, classification and applications, as well as the challenges they face.
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.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
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.
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptxshubhijain836
Centrifugation is a powerful technique used in laboratories to separate components of a heterogeneous mixture based on their density. This process utilizes centrifugal force to rapidly spin samples, causing denser particles to migrate outward more quickly than lighter ones. As a result, distinct layers form within the sample tube, allowing for easy isolation and purification of target substances.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
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.
(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.
2. A&A 674, A43 (2023)
1. Introduction
Transiting long-period planets are valuable objects, but they are
also challenging to characterize. These planets have a low transit
probability, and giant planets have a lower occurrence rate than
lower-mass planets (e.g., Mayor et al. 2011; Petigura et al. 2018;
Fulton et al. 2021), which explains why so few of them have been
detected so far. Besides, searching for the transit of long-period
planets known from radial velocity surveys would be very time
consuming, due to the low probability of transit. The four-year
baseline of the Kepler mission (Borucki et al. 2010) enabled the
characterization of several transiting planets with orbital peri-
ods ranging from 100 to 300 days (e.g., Mancini et al. 2016;
Dubber et al. 2019; Dalba et al. 2021), and dedicated searches
revealed a few dozen transiting planet candidates with orbital
periods between 100 days to several years (Wang et al. 2015;
Uehara et al. 2016; Foreman-Mackey et al. 2016).
The Transiting Exoplanet Survey Satellite (TESS; Ricker
et al. 2015) scans the whole sky, with each TESS sector being
observed for 27 days almost continuously. As several subsequent
sectors may overlap, some parts of the sky are monitored for
up to one year with few interruptions. Exoplanets with orbital
periods longer than 27 days will only show one transit event
in a TESS sector. Targeting single transit events opens the door
to the discovery of planets with longer orbital periods than the
ones found by searching periodic events. Several pipelines have
thus been developed to search for single transit events (e.g.,
Gill et al. 2020a; Montalto et al. 2020). However, the period of
these single-transiting candidates is mainly unconstrained. The
nature of the TESS survey leads to multiple observations of
the same sectors but about two years apart, and consequently
the second transit of the same candidate may be detected. The
range of possible orbital periods for a duo-transit candidate then
becomes reduced to a discrete set of periods. Osborn (2022)
have presented a new code to estimate the probability of each
period alias. Their classification allows one to prioritize the
follow-up of a duo-transit candidate by scheduling observations
of the highest-probable periods first. Despite a strong detection
bias against planets at long orbital periods, the TESS mission
and the efficient follow-up effort has led to an increase of
well-characterized transiting long-period giants (e.g., Gill et al.
2020b; Hobson et al. 2021; Dalba et al. 2022; Ulmer-Moll et al.
2022).
The CHaracterising ExOPlanet Satellite (CHEOPS; Benz
et al. 2021) is the first European Space Agency mission dedicated
to the characterization of known exoplanets around bright stars.
With space-grade photometric precision, CHEOPS can be used
to confirm small transiting planets at long periods (e.g., Bonfanti
et al. 2021; Lacedelli et al. 2022). For the multiplanetary system
ν2
Lupi, the high signal-to-noise ratio of the CHEOPS obser-
vations allowed for precise measurement of the radius of its
three small planets, as shown by Delrez et al. (2021). Notably,
CHEOPS has also been used to recover the orbital periods of
TESS duo-transit candidates through targeted observations of
the possible period aliases (e.g., Garai et al. 2023; Osborn et al.
2023; Tuson et al. 2023).
Long-period planets are ideal objects of study to gain insight
into the formation and evolution of planetary systems, as their
properties are less affected by stellar irradiation and stellar tidal
interactions than close-in objects. For transiting planets, their
planetary radius is measured with transit photometry, and their
planetary mass and eccentricity are often measured through
radial velocity follow-up or transit-timing variations, in the case
of compact multiplanet systems. These fundamental parameters
govern the planetary mean density and can lead to hints regard-
ing a planet’s interior structure.
The study of modestly irradiated giants by Miller & Fortney
(2011) and Thorngren et al. (2016) led to the definition of a plan-
etary mass-metallicity relation, putting the metal enhancement
of the Solar System giants Jupiter and Saturn in an exoplanetary
context. Increasing the sample of long-period transiting exoplan-
ets is essential to refining this relationship and, more broadly,
understanding their formation and evolution processes.
This paper reports the discovery and characterization of a
long-period Neptune-mass planet transiting TOI-5678. The pho-
tometric and spectroscopic observations are described in Sect. 2,
along with the observation strategy. Section 3 details the deter-
mination of the stellar parameters and the system modeling. The
results of the joint modeling and the interior structure model are
presented in Sect. 4 and the conclusions in Sect. 5.
2. Observations
The discovery photometry was obtained from the TESS mis-
sion (Sect. 2.1), and follow-up photometric observations were
performed with the CHEOPS satellite (Sect. 2.2). Ground-
based spectroscopic observations were carried out with the
high-resolution spectrographs CORALIE (Sect. 2.3) and High
Accuracy Radial velocity Planet Searcher (HARPS; Sect. 2.4).
2.1. TESS photometry
The TESS satellite (Ricker et al. 2015) observed TOI-5678 dur-
ing its primary and its first extended mission (year 1 and year 3).
Until September 2023 (TESS cycle 5), no further TESS obser-
vations are planned. TOI-5678 was observed at a two-minute
cadence in three TESS sectors: sector 4 (2018-10-18 to 2018-11-
15), sector 30 (from 2020-09-22 to 2020-10-21), and sector 31
(2020-10-21 to 2020-11-19).
We discovered a planet candidate in the TESS data using
our specialized duo-transit pipeline (Tuson & the CHEOPS Con-
sortium 2022). This pipeline was created to search for TESS
duo-transits suitable for CHEOPS follow-up. The pipeline con-
catenates the TESS Pre-search Data Conditioned Simple Aper-
ture Photometry (PDCSAP) light curves from the primary and
extended mission, detrends the light curve using a mean sliding
window, and then runs a box least squares (BLS; Kovács et al.
2002) transit search on the detrended light curve, with param-
eters optimized for duo-transit detection. TOI-5678 returned a
duo-transit candidate with the first transit at the very beginning
of the second orbit of sector 4 and a second transit in sector
30. We checked both transits for asteroid crossing and centroid
shifts (indicating a background eclipsing binary) before deciding
to pursue follow-up observations. This duo-transit candidate was
also independently discovered by the Planet Hunter TESS team
and was announced as a Community Tess Object of Interest in
March 2021.
The light curves from the primary and extended mission
were obtained through the Mikulski Archive for Space Tele-
scopes1
and the data reduction was done at the Science Process-
ing Operation Center (Jenkins et al. 2016). We used the PDCSAP
fluxes and their corresponding errors for our analysis. We gener-
ated target pixel files with tpfplotter (Aller et al. 2020) and
used them to check for the presence of contaminant sources,
down to a magnitude difference of seven. The apertures that were
used to extract the light curves in all three of the sectors are not
1 mast.stsci.edu
A43, page 2 of 15
3. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
Table 1. CHEOPS photometric observations of TOI-5678.
Visit Start time End time Duration Texp Alias File reference
[UT] [UT] [h] [s] [days]
1 2021-09-24 00:54:22 2021-09-24 05:10:29 4.27 60 34.1 CH_PR110048_TG006901_V0200
2 2021-10-10 22:27:20 2021-10-11 02:40:27 4.22 60 39.8 & 59.7 CH_PR110048_TG007201_V0200
3 2021-10-11 03:09:20 2021-10-11 07:36:28 4.45 60 39.8 & 59.7 CH_PR110048_TG007801_V0200
4 2021-10-26 17:44:21 2021-10-26 23:24:30 5.67 60 31.1 CH_PR110048_TG006701_V0200
5 2021-11-03 17:56:20 2021-11-03 23:34:30 5.64 60 47.73 CH_PR110048_TG007501_V0200
Notes. The Alias column corresponds to the period aliases compatible with an expected transit at the date of observation. Texp is the exposure
time.
contaminated by neighboring stars. We did not include a dilu-
tion factor while modeling the TESS light curves because of the
absence of contaminating sources.
2.2. CHEOPS photometry
As a space-based observatory, CHEOPS (Benz et al. 2021) is
designed to perform ultra-high precision photometry on bright
targets, one star at a time. Science observations with the satellite
started in April 2020 and are mainly dedicated to the follow-up
of known transiting exoplanets (e.g., Lendl et al. 2020; Bonfanti
et al. 2021; Szabó et al. 2021; Barros et al. 2022). The CHEOPS
telescope has a 30 cm effective aperture with a 1024 x 1024-
pixel, back illuminated Charge-Coupled Device detector (Deline
et al. 2020). The CHEOPS bandpass covers a broad range of opti-
cal wavelengths, from 330 to 1100 nm. As shown by Lendl et al.
(2020), CHEOPS is able to reach a photometric precision of ten
parts per million (ppm) per one hour of binning for a very bright
star (Vmag = 6.6). For faint stars, CHEOPS also complies with
its requirement, as it provided a photometric precision of 75 ppm
in three hours of integration time for a star of Vmag 11.9 (Benz
et al. 2021).
TOI-5678 was observed with CHEOPS from 2021-09-24 to
2021-11-03 through the Duos program (CH_PR110048: “Duos,
Recovering long period duo-transiting planets”), which is part
of the CHEOPS Guaranteed Time Observation program. This
program aims to solve the orbital periods of TESS duo-transit
candidates around stars with a V magnitude greater than 12.
A detailed explanation of the Duos program and its scheduling
strategy is presented in Sect. 3.2 of Osborn et al. (2022). The
filler program targets candidates with a transit depth between
two and four parts per thousand (ppt) such that the observation
of a partial transit is sufficient to obtain a detection of the signal.
Each CHEOPS visit lasts at least three CHEOPS orbits in order
to correctly model instrumental trends and to identify the partial
transit. Five CHEOPS visits of TOI-5678 were observed with an
exposure time of 60 s. The details of the observations are pre-
sented in Table 1. The fifth visit of TOI-5678 showed an ingress,
and this transit event uniquely validated the orbital period of the
candidate. The CHEOPS light curve is shown in Fig. 1, and no
strong systematic trends are visible in the raw data. After this
visit, we stopped the monitoring of the target.
TOI-5678 has a V magnitude of 11.4 and is one of the faintest
targets to be observed with CHEOPS. We used point spread
function (PSF) photometry implemented in the PSF imagette
photometric extraction package (PIPE2
) to reduce the CHEOPS
data. In the case of TOI-5678, the PIPE data reduction was
shown to perform better than the standard the data reduction
2 github.com/alphapsa/PIPE
0.0 0.2 0.4 0.6 0.8 1.0
Time (BJD-2459481)
0.0
0.2
0.4
0.6
0.8
1.0
0.6 0.7
0.9975
1.0000
1.0025
17.5 17.6 17.7 17.8
33.3 33.4
0.9975
1.0000
1.0025
41.3 41.4
Normalized
flux
Fig. 1. Raw CHEOPS light curve of TOI-5678 b. The data covers five
period aliases and displays an ingress in the bottom-right plot.
pipeline version 13.1 (DRP 13.1; Hoyer et al. 2020). Over the five
CHEOPS visits, the average mean absolute deviation of the PIPE
light curve is 120 ppm lower than the DRP 13.1 one using the
default 25-pixel aperture. We chose to use the PIPE data reduc-
tion routines for our analysis. We selected data points without
any recognized issue (flag equals zero). We removed data points
for which the corresponding background flux has a value higher
than 300 e−
/pixel. The background subtraction routine became
unreliable due non-linear behavior beyond this threshold. Along
with the time, flux, and errors on the flux, we extracted the back-
ground, roll angle (θ), and the X and Y coordinates to be used
as detrending vectors in the analysis. We included detrending
parameters, which improved the log-evidence values of the fit by
a factor of five. The modulation in roll angle is correlated with
the estimated contamination by nearby stars, but this contami-
nation is quite low with a mean flux of 0.01% compared to the
target mean flux. We found that a linear combination of cos(2θ)
and cos(3θ) was efficient at removing the roll angle dependence.
A table of the PIPE reduced CHEOPS photometric observations
is available in a machine-readable format at the CDS.
2.3. CORALIE spectroscopy
Spectroscopic vetting and radial velocity follow-up was carried
out with CORALIE (Queloz et al. 2001). The high-resolution
fiber-fed spectrograph CORALIE is installed at the Nasmyth
focus of the Swiss 1.2 m Euler telescope (La Silla, Chile)3
.
CORALIE has a spectral resolution of 60 000, and the sam-
pling per resolution element is equal to three pixels. Two fibers
3 eso.org/public/teles-instr/lasilla/swiss
A43, page 3 of 15
4. A&A 674, A43 (2023)
Table 2. Radial velocities of TOI-5678.
Time RV RV error Instrument
BJD [ms−1
] [ms−1
]
2 459 464.78269 −3.86711 25.68928 CORALIE
2 459 470.72244 49.11076 27.98340 CORALIE
2 459 475.74732 36.17593 18.78204 CORALIE
...
2 459 622.55655 55.81805 2.972752 HARPS
2 459 624.56960 51.25084 2.803944 HARPS
2 459 625.53665 54.48176 2.21336 HARPS
Notes. Full table is available at the CDS.
were used for the fiber injection. The first fiber was dedicated to
the target observation, and the second fiber could collect light
from a Fabry-Pérot etalon or the sky to allow for simultaneous
wavelength calibration or background subtraction.
TOI-5678 was observed with CORALIE as part of a support
program for CHEOPS to vet the candidates with spectroscopy
and to evaluate the level of stellar activity visible in the radial
velocity. Two high-resolution spectra were obtained several days
apart. These observations are useful to rule out clear eclipsing
binary scenarios. TOI-5678 was then monitored at a low cadence
to reveal possible long-term trends or strong activity signals.
We used the standard data reduction pipeline to extract the
stellar radial velocities using the cross-correlation technique.
The stellar spectrum of TOI-5678 is cross-correlated with a G2
mask, which is the closest mask to the stellar type to obtain a
cross-correlation function (CCF; e.g., Pepe et al. 2002). The out-
puts of the pipeline are the radial velocity and its associated error
as well as additional parameters derived from the CCF, such as
the full width half maximum (FWHM), contrast, and bisector
inverse slope (BIS).
We collected 14 radio velocity measurements of TOI-5678
(from 2021-09-07 to 2022-01-23) with an exposure time vary-
ing between 1800 and 2100 s, depending on the observing
conditions. The radial velocity observations are detailed in
Table 2.
2.4. HARPS spectroscopy
Once the orbital period of the candidate was solved with
CHEOPS observations, we decided to add TOI-5678 to an
ongoing HARPS program dedicated to the follow-up of warm
transiting giants (108.22L8.001, PI: Ulmer-Moll). A fiber-fed
spectrograph, HARPS has a spectral resolution of about 115 000.
It is installed at the 3.6 m telescope in La Silla, Chile (Mayor
et al. 2003). TOI-5678 was observed with the high-accuracy
mode of HARPS from 2021-11-12 to 2022-02-15, and we
obtained 23 HARPS measurements with an exposure time
varying between 1800 and 2100 s. The average signal-to-noise
ratio is equal to 40 at 550 nm. The radial velocity observations
are presented in Table 2. The data reduction was performed
with the standard data reduction pipeline (Lovis & Pepe 2007).
The radial velocities were extracted with the cross-correlation
technique using a G2 mask. Along with the radial velocities,
the CCFs are used to derive several stellar activity indicators,
such as the FWHM, contrast, and BIS. Additional parameters
were also extracted from the spectra, namely, the S, Hα, Na,
and Ca indexes. The HARPS spectra were co-added in order to
derive stellar parameters, and the analysis is detailed in Sect. 3.1.
3. Methods
3.1. Stellar parameter determination
In order to derive precise stellar parameters, the HARPS spectra
of TOI-5678 were doppler-shifted according to their radial veloc-
ity measured during the data reduction and co-added in a single
1D master spectrum. We used ARES+MOOG to derive stel-
lar atmospheric parameters (Teff, log g, microturbulence, [Fe/H])
following the same methodology described in Santos et al.
(2013); Sousa (2014), and Sousa et al. (2021). The latest version
of ARES4
(Sousa et al. 2007, 2015) was used to consistently
measure the equivalent widths of selected iron lines based on
the line list presented in Sousa et al. (2008). A minimization
process was used in this spectral analysis to find ionization and
excitation equilibrium and converge to the best set of spectro-
scopic parameters. The iron abundances were computed using
a grid of Kurucz model atmospheres (Kurucz 1993) and the
radiative transfer code MOOG (Sneden 1973). The converged
spectroscopic parameters are listed in Table 3. The stellar abun-
dances [Mg/H] = 0.07 ± 0.06 dex and [Si/H] = 0.00 ± 0.04 dex
were derived using the classical curve-of-growth analysis
method, assuming local thermodynamic equilibrium (e.g.,
Adibekyan et al. 2012, 2015). The same codes and models were
used for the abundance determinations.
To determine the stellar radius of TOI-5678, we used a
Markov chain Monte Carlo infrared flux method (MCMC
IRFM; Blackwell & Shallis 1977; Schanche et al. 2020) that
computes the stellar angular diameter and effective temperature
via known relationships of these properties and the apparent
bolometric flux. We used the stellar spectral parameters as priors
to construct a spectral energy distribution from stellar atmo-
spheric models that were attenuated via extinction estimates
and used to compute the bolometric flux that is compared to the
observed data taken from the most recent data releases for the
bandpasses Gaia G, GBP, and GRP; 2MASS J, H, and K; and
WISE W1 and W2 (Skrutskie et al. 2006; Wright et al. 2010;
Gaia Collaboration 2021), with the stellar atmospheric models
taken from the ATLAS catalogs (Castelli & Kurucz 2003). By
converting the stellar angular diameter to the stellar radius
using the offset corrected Gaia Early Data Release 3 parallax
(Lindegren et al. 2021), we obtained R⋆ = 0.938 ± 0.007 R⊙.
Finally, assuming Teff, [Fe/H], and R⋆ as input parameters,
we determined the isochronal mass M⋆ and age t⋆ by using
two different stellar evolutionary models. The first pair of mass
and age values was computed through the isochrone place-
ment algorithm (Bonfanti et al. 2015, 2016), which interpolates
the input parameters within pre-computed grids of PARSEC5
v1.2S (Marigo et al. 2017) isochrones and tracks. The sec-
ond pair of mass and age values was retrieved by the Code
Liégeois d’Évolution Stellaire (CLES;, Scuflaire et al. 2008)
code, which computes the best-fit stellar evolutionary tracks
following the Levenberg-Marquadt minimization scheme as pre-
sented in Salmon et al. (2021). After carefully checking for
the mutual consistency of the two respective pairs of outcomes
through the χ2
-based criterion broadly discussed in Bonfanti
et al. (2021), we merged the output distributions of both the
stellar mass and age, ending up with the following estimates:
M⋆ = 0.905+0.039
−0.041 M⊙ and t⋆ = 8.5 ± 3.0 Gyr. The results are
presented in Table 3.
4 The latest version, ARES v2, can be downloaded at https://
github.com/sousasag/ARES
5 PAdova and TRieste Stellar Evolutionary Code: http://stev.
oapd.inaf.it/cgi-bin/cmd
A43, page 4 of 15
5. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
Table 3. Stellar properties and stellar parameters.
TOI-5678
Other names
2MASS J03093220-3411530 2MASS
Gaia 5048310370810634624 Gaia
TYC 7022-00871-1 Tycho
TESS TIC 209464063 TESS
TOI TOI-5678 TESS
Astrometric properties
RA 03:09:32.2 TESS
Dec −34:11:54.53 TESS
µRA [mas yr−1
] −5.565±0.032 Gaia DR3
µDec [mas yr−1
] −89.15±0.04 Gaia DR3
Parallax [mas] 6.099±0.014 Gaia DR3
Photometric properties
TESS [mag] 10.669±0.006 TESS
V [mag] 11.438±0.012 Tycho
B [mag] 12.031±0.171 Tycho
G [mag] 11.1483±0.0004 Gaia
J [mag] 9.997±0.022 2MASS
H [mag] 9.699±0.021 2MASS
Ks [mag] 9.563±0.023 2MASS
W1 [mag] 9.533±0.023 WISE
W2 [mag] 9.591±0.02 WISE
W3 [mag] 9.552±0.033 WISE
W4 [mag] 9.433±0.524 WISE
TESS luminosity [L⊙] 0.740±0.025 TESS
Bulk properties
Teff [K] 5485 ± 63 Sect. 3.1
Spectral type G7V Sect. 3.1
log g [cm s−2
] 4.34 ± 0.11 Sect. 3.1
Vt micro [km s−1
] 0.82 ± 0.03 Sect. 3.1
[Fe/H] [dex] 0.00 ± 0.01 Sect. 3.1
[Mg/H] [dex] 0.07 ± 0.06 Sect. 3.1
[Si/H] [dex] 0.00 ± 0.04 Sect. 3.1
v sin i [km s−1
] 3.1 ± 1.0 Sect. 3.1
Age [Gyr] 8.5 ± 3.0 Sect. 3.1
Radius [R⊙] 0.938 ± 0.007 Sect. 3.1
Mass [M⊙] 0.905+0.039
−0.041 Sect. 3.1
References. 2MASS: Skrutskie et al. (2006); Gaia EDR3: Gaia
Collaboration (2021); TESS: (Stassun et al. 2019); Tycho: (Høg et al.
2000); WISE: Wright et al. (2010).
Following procedures going back to the CoRoT mission
(Fridlund 2008), we applied the Interactive Data Language pack-
age Spectroscopy Made Easy (Piskunov et al. 1995; Valenti &
Piskunov 1996; Piskunov & Valenti 2017). With this code, and
using the stellar parameters given above as fixed inputs, we then
synthesized a spectrum based on the well-determined stellar
atmospheric grid MARCS 2012 (Gustafsson et al. 2008) using
atomic and molecular parameters from the Vienna Atomic Line
Database (Piskunov et al. 1995) for the synthesis. Again follow-
ing schemes outlined in Fridlund et al. (2020), and references
therein, and while keeping the turbulent velocities Vt macro and
Vt micro fixed at the empirical values found in the literature
(Gray 2008; Bruntt et al. 2010; Doyle et al. 2014), we found v sin i
to be 3.1±1 km s−1
.
30 40 60 80 100 200 300 400 600 800
Period [d]
10−5
10−4
10−3
0.01
0.1
Prob.
p > 1%
p > 0.1%
p > 10−4
p > 10−5
True period
Fig. 2. Marginalized probabilities of the possible period aliases,
obtained with MonoTools, from TESS data only. The triangle indicates
the true period of TOI-5678 b.
3.2. TESS photometric analysis
We selected TOI-5678 as a potential target for the CHEOPS
Duos program, as its TESS light curve presents two single tran-
sits separated by a data gap of about 716 days. As for all targets
in this CHEOPS program, we ran a photometric analysis with
the software package MonoTools (Osborn 2022)6
. MonoTools
is especially adapted to detecting, vetting, and, modeling multi-
planet systems in the case of single- and duo-transiting planets.
The first step was to verify that the transit is not due to a rise in
the background flux, which is indicative of an asteroid crossing
or an artifact. We also tested that the transit model is a better fit
to the event compared to a sine wave or a polynomial function.
We checked that there was no feature in the X and Y coordinates
coincident with the transit event, which would indicate a pos-
sible eclipsing binary or blend scenario. Finally, we confirmed
that the shape, depth, and duration of the two transit events are
compatible.
The second step was to model the duo-transit in order to
determine which period aliases to observe. MonoTools uses
a Bayesian framework to marginalize over the possible period
aliases and compute the probability distribution of the period
aliases, as shown in Fig. 2. This method fits the impact param-
eter, transit duration, and radius ratio in a way that is agnostic
of the exoplanet period. When combined with stellar param-
eters, such as bulk density (Stassun et al. 2019), the transit
model allowed us to derive an instantaneous transverse planetary
velocity and, therefore, to compute a marginalized probability
distribution for each allowed period alias. This method uses a
combination of the model likelihood and priors from a combi-
nation of window function and occurrence rate (P−2
; Kipping
2018), a geometric transit probability (pg ∝ a−1
∼ P−2/3
; e.g.,
Winn 2010), and an eccentricity prior (Kipping 2013b). For each
allowed period alias, the eccentricity prior was applied using the
eccentricity distribution implied by the ratio of the transverse
planetary velocity to the circular velocity at that period.
Once the probabilities of the different period aliases were
computed, we organized the CHEOPS observations. We sched-
uled 13 of the highest-probability aliases (covering a sum of
85% of the probability space) on CHEOPS; however, due to
scheduling constraints, only a fraction of these are likely to be
6 github.com/hposborn/MonoTools
A43, page 5 of 15
6. A&A 674, A43 (2023)
475 500 525 550 575 600 625
Time (BJD - 2459000)
−50
0
50
RV
(m.s
−1
)
CORALIE
HARPS
100 101 102
Period (days)
0.0
0.2
0.4
0.6
Normalized
power
1%
Fig. 3. Top: time series of radial velocities from CORALIE (blue
dots) and HARPS (red triangles) for TOI-5678. The HARPS error
bars are smaller than the marker. Bottom: generalized Lomb-Scargle
periodogram of the radial velocities (blue line). The 1% false alarm
probability level is indicated with a black line. The highest peak corre-
sponds to a period of about 48.8 days.
observed. The transits of TOI-5678 b are sufficiently deep such
that CHEOPS does not require full transit coverage in order to
successfully recover a transit. We chose to only schedule partial
transits, which required 2.8-orbit (4.6-h) observations for each
alias. We left a large degree of flexibility regarding the start time
such that at least one orbit of in-transit data would always be
observed. This flexibility improves the likelihood of observations
of TOI-5678 b aliases being selected by the CHEOPS scheduler,
even at low internal priority.
We realized a posteriori that the data from the first obser-
vation, labeled “visit 1” in Table 1, covers only in-transit times.
At first, this visit was inconclusive since we did not have any
baseline signal. Further observations proved that visit 1 is in
agreement with the baseline flux and rules out the 34.1-day
period alias. Visits 2 and 3 cover the period aliases 39.8 days and
59.7 days, respectively, and we obtained a clear non-detection of
the transit signal7
. Visit 4 covers the 31.1-day period alias and
also results in a clear non-detection. Visit 5 covers the 47.73- day
alias, and a transit ingress was detected. We stopped the
CHEOPS observations after the successful detection in the fifth
visit.
3.3. Radial velocity analysis
The CORALIE observations of TOI-5678 show a low radial
velocity root mean square of 15 ms−1
over two months, for
an average radial velocity precision of 20 ms−1
. The prelimi-
nary analysis of the TESS data and the period recovery work
done with CHEOPS result in a planetary candidate with an
orbital period of 47.73 days and a radius of 4.9 R⊕. From these
parameters, we estimated the expected mass of the planetary
candidate to be between 18 and 21.5 M⊕ (based on the empirical
mass-radius relations from Bashi et al. 2017 and Otegi et al.
2020, respectively), leading to an expected semi-amplitude,
ranging from 3.3 to 3.8 ms−1
. With the HARPS Exposure Time
7 One of the two visits would have been enough to exclude both aliases,
but the Mission Planning System automatically scheduled both visits
and we did not remove one of them.
0.0
0.5
Power
1%
RV
0.0
0.5
Power
1%
Res RV
0.0
0.5
Power
1%
FWHM
0.00 0.05 0.10 0.15 0.20 0.25 0.30
Frequency (days−1)
0.0
0.5
Power
1%
Hα
Fig. 4. Generalized Lomb-Scargle periodogram of the radial velocities,
radial velocity residuals, FWHM, and Hα index (from top to bottom).
The 1% false alarm probability level is indicated with a black line.
Calculator8
, we computed that the expected radial velocity
precision achievable with a 1800-s HARPS exposure is 1.4 ms−1
for TOI-5678. A detection of the radial velocity signal was
feasible during the next few months of observability (November
to February). The target was then selected to be added to an
ongoing HARPS program with the planned goal of charac-
terizing long-period transiting exoplanets. Figure 3 presents
the radial velocity dataset of TOI-5678 and its corresponding
generalized Lomb-Scargle (GLS) periodogram (Zechmeister &
Kürster 2009), which combines both CORALIE and HARPS
datasets. No significant peak was found in the GLS periodogram
of the following stellar activity indicators: FWHM and bisector
of the CCF or the Hα index. The GLS periodogram of the CCF
contrast shows some peaks at periods unrelated to the period of
the planetary candidate. Figure 4 displays the GLS periodogram
of the CORALIE and HARPS radial velocities, the FWHM of
the CCF, and the Hα index. The radial velocity residuals were
calculated by removing the best-fit Keplerian model from the
joint analysis in Sect. 3.4.
A preliminary analysis of the radial velocity dataset was
performed with the software package kima (Faria et al. 2018),
which is dedicated to the analysis of multiplanetary systems and
takes into account the radial velocity time series and their asso-
ciated activity indicators. Using a Bayesian framework, kima
models radial velocity data as a sum of Keplerian functions.
Data from different spectrographs can be considered with a free
radial velocity offset between datasets. The number of planets is
a free parameter of the model, and we chose to set it to a prior
uniformly distributed as either zero, one, or two. We set the max-
imum value of the orbital period prior to the time span of the
dataset, and the upper bound of the semi-amplitude prior was set
to twice the peak-to-peak of the radial velocities. Table A.1 lists
all priors used in this analysis.
The analysis of the CORALIE and HARPS data of TOI-5678
with kima led to a detection of one planetary signal with
an orbital period of 48.63+2.61
−2.29 days and a semi-amplitude of
3.94+0.79
−0.82 ms−1
. The Bayes factor between the no planet and
one planet model is equal to 52 and 0.6 between the one
planet and two planet model. While the Bayes factor for the
one planet model is not superior to 150, a common threshold
for significance, it indicates moderate evidence for this model
8 eso.org/observing/etc
A43, page 6 of 15
7. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
(Feroz et al. 2011). The presence of transits with a compatible
period adds credibility to the signal.
3.4. Joint analysis
We combined the photometric and radial velocity data to per-
form an analysis of the planetary system around TOI-5678. We
used the software package juliet (Espinoza et al. 2019) to
jointly model the datasets, as juliet models multiplanetary
systems, including transiting and non-transiting planets, within
a Bayesian framework. The light curve modeling in juliet
is based on batman (Kreidberg 2015) for the model of the
planetary transits. The stellar activity and instrumental corre-
lations can be specified with Gaussian processes or parametric
functions, including linear models (LMs). Photometric datasets
from different instruments can be included in the model by
adding independent jitter and offset terms as well as dilution fac-
tors. To model the Keplerian orbits in the radial velocity data,
we used RadVel (Fulton et al. 2018). Several sampling meth-
ods can be implemented in juliet, and we chose the nested
sampling method dynesty (Speagle 2019). Data from multiple
instruments can be incorporated using separate values for radial
velocity jitter by allowing for offsets between the datasets.
Two planetary transits are visible in the TESS data in sec-
tors 4 and 30. We chose to include these two relevant sectors and
to exclude sector 31, which does not contain any transit feature.
Since only the fifth CHEOPS visit displays a partial transit of
TOI-5678 b, we chose to only include this last visit for the joint
modeling. The model parameters for the planet are the orbital
period, the planet-to-star radius ratio, the mid-transit time of the
first transit, the impact parameter, the argument of periastron,
and the eccentricity. Notably, we used a Beta prior for the eccen-
tricity and a uniform prior between 40 and 60 days for the orbital
period. We compared the evidence values of different fits in order
to choose the detrending of the TESS data (inclusion of Gaussian
processes) and the modeling of the eccentricity. We checked the
impact of the eccentricity Beta prior by changing it from a Beta
prior to a uniform prior between zero and one. We found that
both priors lead to similar posterior distributions as well as an
eccentricity of 0.14+0.07
−0.07 for the Beta prior and 0.15+0.06
−0.08 for the
uniform prior. Regarding the stellar density, we found that the
density derived from the TESS photometric fit with MonoTools
is in agreement with the one derived in Sect. 3.1. In this joint
fit, the stellar density is governed by a normal prior informed by
the stellar spectroscopic analysis done in Sect. 3.1. Because the
TESS and CHEOPS bandpasses are different, we modeled the
limb darkening with a quadratic law using two different sets of
q1 and q2 parameters (Kipping 2013a). The priors used in the
limb-darkening parameters were derived from the LDCU9
code,
which is a modified version of the python routine implemented
by Espinoza & Jordán (2015). It computes the limb-darkening
coefficients and their corresponding uncertainties using a set
of stellar intensity profiles that account for the uncertainties in
the stellar parameters. The stellar intensity profiles were gener-
ated based on two libraries of synthetic stellar spectra: ATLAS
(Kurucz 1979) and PHOENIX (Husser et al. 2013). Table B.1
details the priors used for all the model parameters.
The TESS photometric variability was taken into account
in one Gaussian process for each sector using an approximate
Matern kernel. The CHEOPS light curves are known to have
trends correlated with the roll angle of the spacecraft. Therefore,
we used LMs to decorrelate the CHEOPS data. The following
9 https://github.com/delinea/LDCU
Table 4. Fitted and derived parameters for TOI-5678 b.
Parameters TOI-5678 b
Fitted parameters
Orbital period [days] 47.73022+0.00014
−0.00013
Time of transit T0 [days] 2458424.7059+0.0035
−0.0032
Radius ratio 0.0480+0.0007
−0.0007
Impact parameter 0.17+0.13
−0.10
Stellar density [kg m−3
] 1551+83
−95
TESS limb darkening q1 0.351+0.027
−0.028
TESS limb darkening q2 0.302+0.010
−0.011
CHEOPS limb darkening q1 0.46+0.04
−0.04
CHEOPS limb darkening q2 0.363+0.013
−0.013
Eccentricity 0.14+0.07
−0.07
Argument of periastron 208+18
−11
Radial velocity semi-amplitude [ms−1
] 3.8+0.7
−0.7
Derived parameters
Planetary radius [R⊕] 4.91+0.08
−0.08
Planetary mass [M⊕] 20+4
−4
Inclination [degrees] 89.83+0.11
−0.12
Semi major axis [au] 0.249+0.005
−0.005
Transit duration [hours] 6.96+0.10
−0.10
Equilibrium temperature [K] 513+8
−7
Instrumental parameters
TESS offset −0.00002+0.00009
−0.00008
TESS jitter [ppm] 1.9+13.6
−1.6
TESS 2 offset −0.00002+0.00005
−0.00005
TESS 2 jitter [ppm] 1.5+11.2
−1.3
CHEOPS offset −0.00121+0.00008
−0.00008
CHEOPS jitter [ppm] 123+84
−91
GP amplitude TESS (relative flux) 0.000028+0.00009
−0.00006
GP time-scale TESS [days] 0.9+0.4
−0.3
GP amplitude TESS 2 (relative flux) 0.00015+0.00007
−0.00004
GP time-scale TESS 2 [days] 1.2+0.09
−0.5
Background CHEOPS (relative flux) −0.00014+0.00006
−0.00006
cos(2θ) CHEOPS [days] 0.00023+0.00011
−0.00012
cos(3θ) CHEOPS [days] 0.00014+0.00008
−0.00008
X coordinate CHEOPS −0.00020+0.00005
−0.00005
Y coordinate CHEOPS −0.00016+0.00005
−0.00005
CORALIE offset [ms−1
] 24.0+4
−4
HARPS offset [ms−1
] 59.7+0.5
−0.5
CORALIE jitter [ms−1
] 3.0+4
−2
HARPS jitter [ms−1
] 1.3+0.4
−0.2
parameters were scaled and then used for linear decorrelation:
background flux, cosine of the roll angle, and the X and Y coor-
dinates. A preliminary analysis of the CHEOPS data allowed
us to select the relevant detrending parameters by comparing
evidence values of the fits. The functional form of the detrend-
ing for the fifth CHEOPS visit is presented in Sect. 2.2 and in
Table 4. The priors on the associated coefficients are all uniform
between −1 and one because the parameters were normalized
and scaled. The photometric and instrumental variabilities were
fitted simultaneously with the transit model.
A43, page 7 of 15
8. A&A 674, A43 (2023)
The additional parameters included for the radial velocity
data are the radial velocity semi-amplitude and jitters and off-
sets for the two instruments (CORALIE and HARPS). The radial
velocity analysis in Sect. 3.3 shows that the HARPS rms is equal
to 2 ms−1
. This value is comparable to the average uncertainty
of the HARPS radial velocity (1.4 ms−1
); thus, we did not add
parametric functions or Gaussian processes to model additional
non-white noise. We ran the final fit using the nested sam-
pling algorithm with 2000 live points and until the uncertainty
regarding the log evidence was smaller than 0.1.
4. Results and discussion
4.1. Planetary system around TOI-5678
Our joint analysis shows that TOI-5678 hosts a transiting planet
with an orbital period of 47.73 days, a planetary mass of 20 ±
4 M⊕, and a planetary radius of 4.91 ± 0.08 R⊕. The transit has a
total duration of 6.96±0.10 h, and the semi-major axis is 0.249±
0.005 au. The orbital eccentricity is equal to 0.14 ± 0.07 and is
consistent at 2 σ with a circular orbit. We note that a circular fit
is only marginally disfavored when compared to a fit with free
eccentricity (∆ ln Z < 2). We estimated the tidal circulariza-
tion timescale with two formulas: one from Adams & Laughlin
(2006) and the other from Jackson et al. (2008). We chose a tidal
quality factor for the planet QP of 105
, which is within the range
of values estimated for the ice and gas giants of the Solar Sys-
tem (Banfield & Murray 1992; Lainey et al. 2009). The stellar
tidal quality factor varied between 106
and 108
(Bonomo et al.
2016), without a significant effect on the timescale. With both
formalisms, we found a circularization timescale on the order
of 20 000–25 000 Gyr. This timescale is much larger than the
age of the system (8.5 ± 3.0 Gyr) and suggests that the orbit of
TOI-5678 b is not subject to tidal circularization.
The HARPS phase-folded radial velocities are shown in
Fig. 5 with the median radial velocity model. TOI-5678 b induces
a radial velocity signal with a semi-amplitude of 3.8 ± 0.7 ms−1
.
The HARPS jitter is 1.3+0.4
−0.2 ms−1
and the HARPS rms is about
2.1 ms−1
. The CORALIE radial velocities were used for the joint
fit; they are not displayed in Fig. 5 due to their large scatter
and for improved readability. After five months of radial velocity
monitoring, we did not measure any significant drift.
Figure 6 presents the TESS light curves modeled with
Gaussian process regression and the CHEOPS light curve mod-
eled with a combination of linear functions. The standard
deviation of the two-minute, ten-minute, and one-hour binned
residuals for the TESS light curves are 1430, 650, 260 ppm for
sector 4 and 1480, 660, 265 ppm for sector 30, respectively. The
full model of sector 4 appears flat in the top-left panel of Fig. 6
because the variations of the Gaussian process model are smaller
in comparison to the transit depth. The CHEOPS data have a
standard deviation of the two-minute, ten-minute, and one-hour
binned residuals of 450, 200, 110 ppm. The posterior distribu-
tions of the fitted parameters for TOI-5678 b along with the
stellar density and radial velocity semi-amplitude are presented
in Fig. C.1. Table 4 details the final parameters and associated
uncertainties of TOI-5678 b.
4.2. TOI-5678 b within the exoplanet population
TOI-5678 b joins the growing sample of transiting exoplan-
ets with orbital periods larger than 15 days and sizes between
Neptune and Saturn (e.g., Dalba et al. 2020; König et al. 2022).
At the lower limit in mass of the group of planets between the
−0.4 −0.2 0.0 0.2 0.4
Phases
−10
−5
0
5
10
RV
(m.s
−1
)
Median model
1σ uncertainty
2540 2560 2580 2600 2620
Times (BJD-2457000)
−5
0
5
Residuals
(m.s
−1
)
HARPS
Fig. 5. Radial velocities of TOI-5678. Top: HARPS radial velocities
(red dots) as a function of orbital phase. The median Keplerian model
(gray line) is plotted along with its corresponding 1σ uncertainty (gray
shaded area). Bottom: radial velocity residuals (red dots) as a function
of time.
ice and gas giants, TOI-5678 b is an interesting object of study
for its formation mechanism. Under the core accretion scenario,
the planetary core is formed early enough to accrete gas from the
protoplanetary disk, but a relatively small final mass indicates
that gas accretion has stopped and prevented the formation of a
gas giant. For example, Dransfield et al. (2022) discovered a mul-
tiplanetary system of three long-period transiting sub-Neptunes,
with orbital periods of 22, 56, and 84 days. The planets have
very different mean densities, which displays the different out-
comes of planetary formation and evolution within one system.
The diversity of intermediate-mass exoplanets seems to be easily
explained when studying the formation of Uranus and Neptune
(Helled & Bodenheimer 2014; Valletta & Helled 2022). The
authors demonstrate that slight changes in the protoplanetary
disk and the environment of the planetary embryos (e.g., core
accretion rate, solid surface density) lead to planets with greater
differences in mass and composition.
We present TOI-5678 b within the population of transit-
ing exoplanets in Fig. 7. We downloaded the NASA exoplanet
database10
on February 28, 2023, and selected confirmed exo-
planets with radius uncertainties lower than 8% and mass uncer-
tainties lower than 20%. With a planetary radius of 4.91 ±
0.08 R⊕ and a stellar insolation of 11.5 ± 0.7 S ⊕, TOI-5678 b
is larger than the planets in the group of volatile-rich sub-
Neptunes. The planetary mean density of TOI-5678 b is equal
to 0.170 ± 0.034 ρ⊕, suggesting that the planet could host a large
fraction of water or gas. When compared to Neptune, TOI-5678 b
has a similar mass (1.17 ± 0.23 MH) but a larger radius
(1.262 ± 0.021 RH), implying a lower planetary mean density
(0.57 ρH). We investigate the interior structure in detail in the
following section.
Additional information on the formation and evolution of
warm exoplanets can be obtained through study of their atmo-
spheres and their spin-orbit angles. We estimated the transmis-
sion spectrum metric (TSM; Kempton et al. 2018) of TOI-5678 b
to be 40. This TSM value is rather low but still places TOI-5678 b
in the top five targets with radii superior or equal to Neptune
receiving less than 25 S⊕ (upper-right corner of Fig. 7).
10 exoplanetarchive.ipac.caltech.edu
A43, page 8 of 15
9. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
1424 1426 1428 1430
Time (BJD -2457000)
0.9950
0.9975
1.0000
1.0025
1.0050
1.0075
Relative
flux
Transit + GP model
TESS 4
2134 2136 2138 2140 2142
Time (BJD -2457000)
0.9950
0.9975
1.0000
1.0025
1.0050
1.0075
Transit + GP model
TESS 30
−0.2 −0.1
Time (BJD -2459522.5)
0.9950
0.9975
1.0000
1.0025
1.0050
1.0075
Transit + LM model
CHEOPS
−5 0 5
0.994
0.996
0.998
1.000
1.002
1.004
Relative
flux
Transit model
TESS 4 detrended
−5 0 5
0.994
0.996
0.998
1.000
1.002
1.004 Transit model
TESS 30 detrended
−6 −4 −2
0.994
0.996
0.998
1.000
1.002
1.004 Transit model
CHEOPS detrended
−5 0 5
Hours
−5000
0
5000
Residuals
(ppm)
−5 0 5
Hours
−5000
0
5000
−6 −4 −2
Hours
−5000
0
5000
Fig. 6. Photometric observations of TOI-5678. Top row: Light curves from both TESS sectors (green and purple dots) and CHEOPS observation
(red dots). The full median model is plotted as a black line. Middle row: detrended and phase-folded data from both TESS sectors (green and purple
dots) and the CHEOPS observation (red dots). The phase-folded transit model is displayed in black. The dots outlined in black in all three panels
show the ten-minute binned data. Bottom row: residuals in parts per million between the full model and the respective light curve.
To illustrate the amplitude of the signal that would be seen
by a James Webb Space Telescope (JWST) observation, we com-
puted synthetic transmission spectra of TOI-5678 b using the
PYRAT BAY modeling framework (Cubillos & Blecic 2021). For
simplicity, we assumed an atmosphere in thermochemical equi-
librium at the planet’s equilibrium temperature and simulated
two different metallicities: 70× and 10× solar. For reference,
the C/H ratio for Neptune and Uranus (of similar mass to
TOI-5678 b) is estimated to be 80 ± 20× solar (e.g., Atreya
et al. 2020). Figure 8 shows the model spectra along with
simulated observations from the JWST NIRPSpec/G395H and
NIRISS/SOSS instruments (Batalha et al. 2017). The spectra are
generally dominated by H2O bands, but a 3.5 µm CH4 feature
and a 4.4 µm CO2 feature are also visible. The two metallic-
ity cases show detectable variations in the molecular absorption
features.
The planet is also suitable for obliquity measurement
(Rossiter 1924; McLaughlin 1924). We calculated that
TOI-5678 b produces a Rossiter-McLaughlin effect of 7 ms−1
(Eq. (40) from Winn 2010), a value large enough to be measured
with state-of-the-art high-resolution spectrographs, such as
ESPRESSO (Pepe et al. 2021). Only a couple of gas giants with
orbital periods longer than 40 days have an obliquity measure-
ment, while no measurement has been done for Neptune-type
planets at such long periods. One the one hand, Albrecht et al.
(2022) note that warm Jupiters and sub-Saturns with scaled
semi-major axis (a/R⋆) larger than ten have relatively high
obliquities. On the other hand, Rice et al. (2022) have found that
tidally detached warm Jupiters appear more aligned than hot
Jupiters; however, the authors also show that Saturn-type objects
can have a wide range of obliquities. An obliquity measurement
for TOI-5678 can help shed light on its formation and evolution
mechanisms.
4.3. Formation and composition of TOI-5678 b
We applied a Bayesian inference scheme to model the inter-
nal structure of TOI-5678 b. A thorough description of the used
method, which is based on Dorn et al. (2017), can be found
in Leleu et al. (2021). In the following, we briefly summarize
the most important aspects of the model: the assumed priors,
the input parameters, and the forward model that was used to
calculate the likelihood of a set of internal structure parameters.
For the priors, we assumed a distribution that is uniform on
the simplex for the layer mass fractions of the iron core, silicate
mantle, and the water layer, all with respect to the solid core of
the planet (without the H/He atmosphere layer). We set an upper
limit of 50% for the water mass fraction, following Thiabaud
et al. (2014). For the gas mass fraction, a log-uniform distribu-
tion was assumed. It is important to note that the results of the
A43, page 9 of 15
10. A&A 674, A43 (2023)
100
101
102
103
104
Insolation flux (S⊕)
100
101
Radius
(R
⊕
)
RΨ
25 S⊕
TOI-5678 b
Fig. 7. Planetary radius as a function of stellar insolation for exoplanets
with radius and mass uncertainties lower than 8 and 20%, respectively.
Fig. 8. Modeled transmission spectra of the target in the NIR-
Spec/G395H and NIRISS wavelength ranges for two possible metal-
licities, 10× (blue line) and 70× (orange line) solar. Simulated flux
measurements of each instrument are displayed as red points for NIRP-
Spec and as orange ones for NIRISS.
internal structure model depend to a certain extent on the cho-
sen priors. The Bayesian inference model takes both planetary
and stellar observables as input parameters: the mass, radius,
age, effective temperature, and molecular abundances ([Si/H],
[Mg/H], and [Fe/H]) of the star and the transit depth, relative
mass, and period of the planet.
Finally, the forward model we selected assumes a spherically
symmetric planet with four fully distinct layers (iron core, sili-
cate mantle, water, and H/He atmosphere). It uses equations of
state from Hakim et al. (2018), Sotin et al. (2007), Haldemann
et al. (2020), and Lopez & Fortney (2014). We stress that in the
current version of our model, the H/He atmosphere was modeled
independently from the solid part of the planet, and we assumed
a fixed temperature and pressure at the water-gas boundary,
thereby neglecting the effects of the gas layer on the remain-
ing layers of the planet. Moreover, we made the assumption that
the Si/Mg/Fe ratios of the planet and the star are identical (see
e.g., Thiabaud et al. 2015). We note that more recent results
by Adibekyan et al. (2021) confirm that there is a correlation
between the composition of a star and its planets, but the authors
suggest a relationship that is not 1:1.
Figure 9 shows the results of the internal structure model.
While the mass of the H/He layer of TOI-5678 b is reasonably
= 0.14+0.13
0.11
0
.
1
0
.
2
0
.
3
0
.
4
fm
water
= 0.22+0.25
0.20
0
.
3
6
0
.
4
0
0
.
4
4
0
.
4
8
Si
mantle
= 0.39+0.08
0.05
0
.
3
0
.
4
0
.
5
0
.
6
Mg
mantle
= 0.47+0.10
0.10
0
.
8
4
0
.
8
8
0
.
9
2
0
.
9
6
Fe
core
= 0.90+0.09
0.08
0
.
0
8
0
.
1
6
0
.
2
4
0
.
3
2
fmcore
0
.
3
0
.
0
0
.
3
0
.
6
0
.
9
log
M
gas
0
.
1
0
.
2
0
.
3
0
.
4
fmwater
0
.
3
6
0
.
4
0
0
.
4
4
0
.
4
8
Simantle
0
.
3
0
.
4
0
.
5
0
.
6
Mgmantle
0
.
8
4
0
.
8
8
0
.
9
2
0
.
9
6
Fecore
0
.
3
0
.
0
0
.
3
0
.
6
0
.
9
log Mgas
= 0.51+0.18
0.23
Fig. 9. Posterior distributions of the internal structure parameters of
TOI-5678 b. The median and the five and 95 percentiles shown in the
title of each column. The depicted internal structure parameters are: the
layer mass fractions of the iron core and water layer with respect to the
solid planet, the molar fractions of Si and Mg in the mantle and Fe in
the core, and the logarithm of the gas mass in Earth masses.
well constrained and quite large, with 3.2+1.7
−1.3 M⊕, the posterior of
the water mass fraction is almost completely unconstrained. The
molar fraction of iron in the core (Fecore) is also unconstrained
and only varies between the bounds allowed by its prior. Further-
more, the posterior distribution of the radius of the gas layer has
a median of 2.53+0.32
−0.34 R⊕. By combining the planet mass with
the inferred mass of H-He, we predicted a minimum mass of
11.1 M⊕ of heavy elements for TOI-5678 b. A planet with such
a large content of heavy elements likely accreted its core beyond
the ice line (e.g., Venturini et al. 2020a,b).
We compared TOI-5678 b to synthetic planets with similar
parameters produced with the New Generation Planetary Popu-
lation Synthesis (Mordasini et al. 2009), the latest version of the
Bern model (Emsenhuber et al. 2021a,b) available on DACE11
.
We chose the NG76 simulation where 100 embryos are used.
We found that synthetic planets with a radius, mass, and semi-
major axis close to TOI-5678b form at a couple of astronomical
units from their host star. After a first initial growth up to about
10 M⊕, the planets migrate inwards while steadily accreting mass
but without reaching a mass high enough to trigger rapid gas
accretion. These planets are part of the system architecture called
migrated sub-Neptunes (Class II), as described in Emsenhuber
et al. (2023). We note that some planets can also reach about
20 M⊕ by accreting a significant amount of their mass through
collisions. These planets forming through giant impacts origi-
nate from inside the ice line, and their final planetary radius is
usually below 3 R⊕. In contrast, planets originating from outside
the ice line have a larger radius, and they contain a significant
fraction of gas, similar to what we estimated for TOI-5678 b.
The knowledge of both mass and radius of TOI-5678 b allows
us to favor a formation and migration scenario starting outside
11 dace.unige.ch/populationAnalysis
A43, page 10 of 15
11. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
of the ice line. This is also supported by other formation models,
which find that only water-rich planets account for planets with
masses larger than 10 M⊕ and radii larger than 3 R⊕ (Venturini
et al. 2020a, Figs. D1 and D2). This support reinforces the like-
lihood that TOI-5678 b formed beyond the ice line and migrated
inwards later on. Finally, the nearly circular orbit of TOI-5678 b
and long circularization timescale suggest that the hypothesis of
a planet-disk migration is favored over a high eccentricity migra-
tion scenario. This migration hypothesis can be tested via the
measurement of the spin-orbit alignment of the system.
5. Conclusions
This paper reports the discovery TOI-5678 b, a transiting long-
period Neptune-mass planet. Its host is a G7V-type star of solar
metallicity with an age of 8.5 ± 3.0 Gyr. The planet itself is on
an almost circular orbit and has an orbital period of 47.73 days.
Its planetary mass is equal to 20 ± 4 M⊕, and its planetary radius
is equal to 4.91 ± 0.08 R⊕. We used the space-based photomet-
ric satellites TESS and CHEOPS to identify and confirm the
orbital period of TOI-5678 b. We combined the photometric
data with CORALIE and HARPS radial velocities to charac-
terize the system and measure the mass and eccentricity of the
transiting companion. We modeled the interior structure of TOI-
5678 b and constrained the mass of its H/He layer to 3.2+1.7
−1.3 M⊕,
assuming the four-layer model presented in Sect. 4.3. We show
that TOI-5678 b likely formed beyond the ice line and then
migrated inwards to its current location. The long orbital period
of TOI-5678 b prevents it from undergoing strong dynamical
interactions with the host star. Additional observations, such as
Rossiter-McLaughlin measurements, would further improve our
knowledge of the system. Such long-period intermediate-mass
planets as TOI-5678 b provide the opportunity to bridge exo-
planet and Solar System science, providing key information on
the Uranus- and Neptune-like planets.
Acknowledgements. This work has been carried out within the framework
of the National Centre of Competence in Research PlanetS supported by
the Swiss National Science Foundation under grants 51NF40_182901 and
51NF40_205606. The authors acknowledge the financial support of the SNSF.
A.T. acknowledges support from an STFC PhD studentship. M.L. acknowl-
edges support of the Swiss National Science Foundation under grant number
PCEFP2194576. P.M. acknowledges support from STFC research grant num-
ber ST/M001040/1. J.E., Y.A., and M.J.H. acknowledge the support of the
Swiss National Fund under grant 200020_172746. A.Br. was supported by the
SNSA. M.F. and C.M.P. gratefully acknowledge the support of the Swedish
National Space Agency (DNR 65/19, 174/18, 177/19). D.G. and L.M.S. grate-
fully acknowledge financial support from the CRT foundation under Grant No.
2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. C.M.
acknowledges the support from the SNSF under grant 200021_204847 “Plan-
etsInTime”. S.G.S. acknowledges support from FCT through FCT contract
nr. CEECIND/00826/2018 and POPH/FSE (EC). A.C.C. and T.W. acknowl-
edge support from STFC consolidated grant numbers ST/R000824/1 and
ST/V000861/1, and UKSA grant number ST/R003203/1. We acknowledge sup-
port from the Spanish Ministry of Science and Innovation and the European
Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-
80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-
87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de Maeztu-Centro
de Astrobiología (INTA-CSIC), as well as the support of the Generalitat de
Catalunya/CERCA programme. The MOC activities have been supported by
the ESA contract No. 4000124370. S.C.C.B. acknowledges support from FCT
through FCT contracts nr. IF/01312/2014/CP1215/CT0004. X.B., S.C., D.G.,
M.F. and J.L. acknowledge their role as ESA-appointed CHEOPS science team
members. This project was supported by the CNES. The Belgian participa-
tion to CHEOPS has been supported by the Belgian Federal Science Policy
Office (BELSPO) in the framework of the PRODEX Program, and by the
University of Liège through an ARC grant for Concerted Research Actions
financed by the Wallonia-Brussels Federation; L.D. is an F.R.S.-FNRS Postdoc-
toral Researcher. This work was supported by FCT – Fundação para a Ciência
e a Tecnologia through national funds and by FEDER through COMPETE2020
– Programa Operacional Competitividade e Internacionalizacão by these grants:
UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/
32113/2017 & POCI-01-0145-FEDER- 032113, PTDC/FIS-AST/28953/2017 &
POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 & POCI-01-0145-
FEDER-028987, O.D.S.D. is supported in the form of work contract (DL
57/2016/CP1364/CT0004) funded by national funds through FCT. This project
has received funding from the European Research Council (ERC) under the
European Union’s Horizon 2020 research and innovation programme (grant
agreement SCORE No 851555). J.H. supported by the Swiss National Sci-
ence Foundation (SNSF) through the Ambizione grant #PZ00P2_180098. P.E.C.
is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellow-
ship, program J4595-N. B.-O.D. acknowledges support from the Swiss State
Secretariat for Education, Research and Innovation (SERI) under contract num-
ber MB22.00046 and from the Swiss National Science Foundation (PP00P2-
190080). This project has received funding from the European Research Council
(ERC) under the European Union’s Horizon 2020 research and innovation pro-
gramme (project FOUR ACES; grant agreement No 724427). It has also been car-
ried out in the frame of the National Centre for Competence in Research PlanetS
supported by the Swiss National Science Foundation (SNSF). D.E. acknowl-
edges financial support from the Swiss National Science Foundation for project
200021_200726. M.G. and V.V.G. are F.R.S.-FNRS Senior Research Associates.
S.H. gratefully acknowledges CNES funding through the grant 837319. This
work was granted access to the HPC resources of MesoPSL financed by the
Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-
29-01) of the programme Investissements d’Avenir supervised by the Agence
Nationale pour la Recherche. L.Bo., G.Br., V.Na., I.Pa., G.Pi., R.Ra., G.Sc.,
V.Si., and T.Zi. acknowledge support from CHEOPS ASI-INAF agreement n.
2019-29-HH.0. This work was also partially supported by a grant from the
Simons Foundation (PI: Queloz, grant number 327127). I.R.I. acknowledges sup-
port from the Spanish Ministry of Science and Innovation and the European
Regional Development Fund through grant PGC2018-098153-B- C33, as well
as the support of the Generalitat de Catalunya/CERCA programme. Gy.M.Sz.
acknowledges the support of the Hungarian National Research, Development
and Innovation Office (NKFIH) grant K-125015, a a PRODEX Experiment
Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungar-
ian Academy of Science and the support of the city of Szombathely. N.A.W.
acknowledges UKSA grant ST/R004838/1. K.G.I. is the ESA CHEOPS Project
Scientist and is responsible for the ESA CHEOPS Guest Observers Programme.
She does not participate in, or contribute to, the definition of the Guaranteed
Time Programme of the CHEOPS mission through which observations described
in this paper have been taken, nor to any aspect of target selection for the pro-
gramme. The authors acknowledge the use of public TESS data from pipelines at
the TESS Science Office and at the TESS Science Processing Operations Centre.
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1
Observatoire Astronomique de l’Université de Genève, Chemin
Pegasi 51, 1290 Versoix, Switzerland
e-mail: solene.ulmer-moll@astro.up.pt
2
Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6,
3012 Bern, Switzerland
3
Department of Physics and Kavli Institute for Astrophysics and
Space Research, Massachusetts Institute of Technology, Cambridge,
MA 02139, USA
4
Astrophysics Group, Cavendish Laboratory, University of
Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
5
Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
6
Department of Astronomy, Stockholm University, AlbaNova Uni-
versity Center, 10691 Stockholm, Sweden
7
Instituto de Astrofísica e Ciências do Espaço, Universidade do
Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
8
Space Research Institute, Austrian Academy of Sciences, Schmiedl-
strasse 6, 8042 Graz, Austria
9
Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA
Leiden, The Netherlands
10
Department of Space, Earth and Environment, Chalmers Univer-
sity of Technology, Onsala Space Observatory, 439 92 Onsala,
Sweden
11
Dipartimento di Fisica, Universita degli Studi di Torino, via Pietro
Giuria 1, 10125 Torino, Italy
A43, page 12 of 15
13. Ulmer-Moll, S., et al.: A&A proofs, manuscript no. aa45478-22
12
Centre for Exoplanet Science, SUPA School of Physics and
Astronomy, University of St Andrews, North Haugh, St Andrews
KY16 9SS, UK
13
ESTEC, European Space Agency, 2201 AZ Noordwijk,
The Netherlands
14
INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123
Catania, Italy
15
German Aerospace Center (DLR), Institute of Optical Sensor Sys-
tems Rutherfordstraße 2, 12489 Berlin, Germany
16
Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife,
Spain
17
Departamento de Astrofisica, Universidad de La Laguna, 38206 La
Laguna, Tenerife, Spain
18
Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can
Magrans s/n, 08193 Bellaterra, Spain
19
Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona,
Spain
20
Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), ESAC
campus, 28692 Villanueva de la Cañada (Madrid), Spain
21
Departamento de Física e Astronomia, Faculdade de Ciências, Uni-
versidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
22
Center for Space and Habitability, University of Bern,
Gesellschaftsstrasse 6, 3012 Bern, Switzerland
23
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
24
INAF, Osservatorio Astronomico di Padova, Vicolo
dell’Osservatorio 5, 35122 Padova, Italy
25
Admatis, 5. Kandó Kálmán Street, 3534 Miskolc, Hungary
26
Institute of Planetary Research, German Aerospace Center (DLR),
Rutherfordstrasse 2, 12489 Berlin, Germany
27
Université de Paris, Institut de physique du globe de Paris, CNRS,
75005 Paris, France
28
INAF – Osservatorio Astrofisico di Torino, Strada Osservatorio,
20 10025 Pino Torinese (TO), Italy
29
Centre for Mathematical Sciences, Lund University, Box 118, 221 00
Lund, Sweden
30
Aix-Marseille Univ, CNRS, CNES, LAM, 38 rue Frédéric Joliot-
Curie, 13388 Marseille, France
31
Astrobiology Research Unit, Université de Liège, Allée du 6
Août 19C, 4000 Liège, Belgium
32
Space sciences, Technologies and Astrophysics Research (STAR)
Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège,
Belgium
33
Centre Vie dans l’Univers, Faculté des sciences, Université
de Genève, Quai Ernest-Ansermet 30, 1211 Genève 4,
Switzerland
34
Center for Computational Astrophysics, Flatiron Institute,
New York, NY 10010, USA
35
University of Vienna, Department of Astrophysics, Türkenschanzs-
trasse 17, 1180 Vienna, Austria
36
Institute for Computational Science, University of Zurich, Win-
terthurerstr. 190, 8057 Zurich, Switzerland
37
Science and Operations Department – Science Division (SCI-SC),
Directorate of Science, European Space Agency (ESA), European
Space Research and Technology Centre (ESTEC), Keplerlaan 1,
2201 AZ Noordwijk, The Netherlands
38
Konkoly Observatory, Research Centre for Astronomy and Earth
Sciences, 1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary
39
ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter
sétány 1/A, 1117 Budapest, Hungary
40
IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sor-
bonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France
41
Institut d’astrophysique de Paris, UMR7095 CNRS, Université
Pierre & Marie Curie, 98bis blvd. Arago, 75014 Paris, France
42
Department of Astrophysics, University of Vienna, Tuerkenschanzs-
trasse 17, 1180 Vienna, Austria
43
Institute of Optical Sensor Systems, German Aerospace Center
(DLR), Rutherfordstrasse 2, 12489 Berlin, Germany
44
Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università
degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova,
Italy
45
Department of Physics, University of Warwick, Gibbet Hill Road,
Coventry CV4 7AL, UK
46
ETH Zurich, Department of Physics, Wolfgang-Pauli-Strasse 2,
8093 Zurich, Switzerland
47
Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE,
UK
48
Zentrum für Astronomie und Astrophysik, Technische Universität
Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
49
ELTE Eötvös Loránd University, Gothard Astrophysical Observa-
tory, 9700 Szombathely, Szent Imre h. u. 112, Hungary
50
MTA-ELTE Exoplanet Research Group, 9700 Szombathely, Szent
Imre h. u. 112, Hungary
51
Institute of Astronomy, University of Cambridge, Madingley Road,
Cambridge, CB3 0HA, UK
A43, page 13 of 15
14. A&A 674, A43 (2023)
Appendix A: Radial velocity modeling priors
Table A.1. Priors for the radial velocity fit.
Parameters Distribution Value
Number of planets Uniform (0, 1)
Orbital period (days) LogUniform (1, 161)
Semi-amplitude (ms−1
) LogUniform (1, 136)
Eccentricity Kumaraswamy (0.867, 3.03)
Mean anomaly Uniform (-π, π)
Argument of periastron Uniform (0, 2π)
Jitter (ms−1
) LogUniform (1, 200)
Appendix B: Joint modeling priors
Table B.1. Priors for the joint modeling of photometric and radial velocity data.
Parameters Distribution TOI-5678 b
Orbital period (days) Uniform (40, 60)
Time of transit T0 (days) Uniform (2458485.9, 2458486.3)
Radius ratio Uniform (0, 1)
Impact parameter Uniform (0, 1)
Stellar density Normal (685.24, 79.18)
TESS limb darkening q1 Normal (0.274, 0.027)
TESS limb darkening q2 Normal (0.275, 0.029)
CHEOPS limb darkening q1 Uniform (0.47, 0.05)
CHEOPS limb darkening q2 Uniform (0.363, 0.015)
Eccentricity Kumaraswamy / fixed (0.867, 3.03)
Argument of periastron Uniform (0, 2π)
TESS offsets Normal (0, 0.01)
TESS jitters (ppm) LogUniform (0.1, 1000)
CHEOPS offsets Normal (0, 0.01)
CHEOPS jitters (ppm) LogUniform (0.1, 1000)
GP amplitude TESS (relative flux) LogUniform (1e-06, 100.0)
GP time-scale TESS (days) LogUniform (0.001, 100.0)
GP amplitude TESS 2 (relative flux) LogUniform (1e-06, 100.0)
GP time-scale TESS 2 (days) LogUniform (0.001, 100.0)
Background CHEOPS (relative flux) LogUniform (-1, 1)
cos(2θ) CHEOPS (days) Uniform (-1, 1)
cos(3θ) CHEOPS (days) Uniform (-1, 1)
X coordinate CHEOPS LogUniform (-1, 1)
Y coordinate CHEOPS Uniform (-1, 1)
Semi-amplitude (kms−1
) Uniform (0, 100)
Spectrograph offsets (kms−1
) Uniform (-100, 100)
Spectrograph jitters (kms−1
) LogUniform (0.001, 0.2)
Notes. The normal distribution is defined by its mean and variance. The uniform and log-uniform distributions were defined with the lower and
upper bounds of the distribution. The priors on the radial velocity offsets and jitters are identical for CORALIE and HARPS.
A43, page 14 of 15