Haumea—one of the four known trans-Neptunian dwarf planets—
is a very elongated and rapidly rotating body1–3. In contrast to
other dwarf planets4–6, its size, shape, albedo and density are not
well constrained. The Centaur Chariklo was the first body other
than a giant planet known to have a ring system7, and the Centaur
Chiron was later found to possess something similar to Chariklo’s
rings8,9. Here we report observations from multiple Earth-based
observatories of Haumea passing in front of a distant star (a multichord
stellar occultation). Secondary events observed around the
main body of Haumea are consistent with the presence of a ring with
an opacity of 0.5, width of 70 kilometres and radius of about 2,287
kilometres. The ring is coplanar with both Haumea’s equator and the
orbit of its satellite Hi’iaka. The radius of the ring places it close to
the 3:1 mean-motion resonance with Haumea’s spin period—that is,
Haumea rotates three times on its axis in the time that a ring particle
completes one revolution. The occultation by the main body provides
an instantaneous elliptical projected shape with axes of about 1,704
kilometres and 1,138 kilometres. Combined with rotational light
curves, the occultation constrains the three-dimensional orientation
of Haumea and its triaxial shape, which is inconsistent with a
homogeneous body in hydrostatic equilibrium. Haumea’s largest axis
is at least 2,322 kilometres, larger than previously thought, implying
an upper limit for its density of 1,885 kilograms per cubic metre and a
geometric albedo of 0.51, both smaller than previous estimates1,10,11.
In addition, this estimate of the density of Haumea is closer to that
of Pluto than are previous estimates, in line with expectations. No
global nitrogen- or methane-dominated atmosphere was detected.
Galaxy and mass_assembly_gama_panchromatic_data_release_and__the_low_energy_b...Sérgio Sacani
Uma equipe internacional de astrônomos estudou mais de 200 000 galáxias e mediu a energia gerada numa enorme região do espaço com a maior precisão até hoje. Este estudo representa a estimativa mais completa de produção de energia no Universo próximo. A equipe confirmou que a energia produzida nesta região do Universo de hoje é apenas cerca de metade da produzida há dois bilhões de anos atrás e descobriu que este enfraquecimento ocorre em todos os comprimentos de onda que vão desde o ultravioleta ao infravermelho longínquo. O Universo está morrendo lentamente.
O estudo envolve muitos dos telescópios mais poderosos do mundo, incluindo o VISTA e o VST — os telescópios de rastreio do ESO, instalados no Observatório do Paranal, no Chile. Observações de suporte foram obtidas por dois telescópios espaciais operados pela NASA (GALEX e WISE) e por um outro pertencente à Agência Espacial Europeia (Herschel) [1].
Este trabalho realizou-se no âmbito do projeto Galaxy And Mass Assembly (GAMA), o maior rastreio já realizado em múltiplos comprimentos de onda.
“Usamos tantos telescópios terrestres e espaciais quanto nos foi possível para medir a produção de energia de cerca de 200 000 galáxias ao longo do maior intervalo de comprimentos de onda possível,” disse Simon Driver (ICRAR, The University of Western Australia), que lidera a enorme equipe GAMA.
Alexandru Marcu - "Faculty of physics, University of Cluj"SEENET-MTP
Prof. Alexandru Marcu presented Faculty of Physics, Babes-Bolyai University, Cluj-Napoca (Romania) at the SEENET-MTP RC & EC meeting held in Timisoara (Romania), November 22, 2014.
Seven temperate terrestrial planets around the nearby ultracool dwarf star TR...Sérgio Sacani
One aim of modern astronomy is to detect temperate, Earth-like
exoplanets that are well suited for atmospheric characterization.
Recently, three Earth-sized planets were detected that transit (that
is, pass in front of) a star with a mass just eight per cent that of
the Sun, located 12 parsecs away1. The transiting configuration of
these planets, combined with the Jupiter-like size of their host star—
named TRAPPIST-1—makes possible in-depth studies of their
atmospheric properties with present-day and future astronomical
facilities1–3. Here we report the results of a photometric monitoring
campaign of that star from the ground and space. Our observations
reveal that at least seven planets with sizes and masses similar
to those of Earth revolve around TRAPPIST-1. The six inner
planets form a near-resonant chain, such that their orbital periods
(1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small
integers. This architecture suggests that the planets formed farther
from the star and migrated inwards4,5. Moreover, the seven planets
have equilibrium temperatures low enough to make possible the
presence of liquid water on their surfaces6–8.
Measurement of the neutrino velocity with the OPERA detector in the CNGS beamSebastien Bianchin
The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 \pm 6.9 (stat.) \pm 7.4 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 \pm 0.28 (stat.) \pm 0.30 (sys.)) \times 10-5.
Galaxy growth in a massive halo in the first billion years of cosmic historySérgio Sacani
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field1–3. Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far4,5. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey6. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe7. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.
Galaxy and mass_assembly_gama_panchromatic_data_release_and__the_low_energy_b...Sérgio Sacani
Uma equipe internacional de astrônomos estudou mais de 200 000 galáxias e mediu a energia gerada numa enorme região do espaço com a maior precisão até hoje. Este estudo representa a estimativa mais completa de produção de energia no Universo próximo. A equipe confirmou que a energia produzida nesta região do Universo de hoje é apenas cerca de metade da produzida há dois bilhões de anos atrás e descobriu que este enfraquecimento ocorre em todos os comprimentos de onda que vão desde o ultravioleta ao infravermelho longínquo. O Universo está morrendo lentamente.
O estudo envolve muitos dos telescópios mais poderosos do mundo, incluindo o VISTA e o VST — os telescópios de rastreio do ESO, instalados no Observatório do Paranal, no Chile. Observações de suporte foram obtidas por dois telescópios espaciais operados pela NASA (GALEX e WISE) e por um outro pertencente à Agência Espacial Europeia (Herschel) [1].
Este trabalho realizou-se no âmbito do projeto Galaxy And Mass Assembly (GAMA), o maior rastreio já realizado em múltiplos comprimentos de onda.
“Usamos tantos telescópios terrestres e espaciais quanto nos foi possível para medir a produção de energia de cerca de 200 000 galáxias ao longo do maior intervalo de comprimentos de onda possível,” disse Simon Driver (ICRAR, The University of Western Australia), que lidera a enorme equipe GAMA.
Alexandru Marcu - "Faculty of physics, University of Cluj"SEENET-MTP
Prof. Alexandru Marcu presented Faculty of Physics, Babes-Bolyai University, Cluj-Napoca (Romania) at the SEENET-MTP RC & EC meeting held in Timisoara (Romania), November 22, 2014.
Seven temperate terrestrial planets around the nearby ultracool dwarf star TR...Sérgio Sacani
One aim of modern astronomy is to detect temperate, Earth-like
exoplanets that are well suited for atmospheric characterization.
Recently, three Earth-sized planets were detected that transit (that
is, pass in front of) a star with a mass just eight per cent that of
the Sun, located 12 parsecs away1. The transiting configuration of
these planets, combined with the Jupiter-like size of their host star—
named TRAPPIST-1—makes possible in-depth studies of their
atmospheric properties with present-day and future astronomical
facilities1–3. Here we report the results of a photometric monitoring
campaign of that star from the ground and space. Our observations
reveal that at least seven planets with sizes and masses similar
to those of Earth revolve around TRAPPIST-1. The six inner
planets form a near-resonant chain, such that their orbital periods
(1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small
integers. This architecture suggests that the planets formed farther
from the star and migrated inwards4,5. Moreover, the seven planets
have equilibrium temperatures low enough to make possible the
presence of liquid water on their surfaces6–8.
Measurement of the neutrino velocity with the OPERA detector in the CNGS beamSebastien Bianchin
The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 \pm 6.9 (stat.) \pm 7.4 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 \pm 0.28 (stat.) \pm 0.30 (sys.)) \times 10-5.
Galaxy growth in a massive halo in the first billion years of cosmic historySérgio Sacani
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field1–3. Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far4,5. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey6. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe7. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.
Complete Photoproduction Experiments - 12th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, Virginia, USA, 31 May-4 June 2010. AIP Conference Proceedings, October 2011, Vol. 1374, pp. 17-22, ISSN: 0094-243X, doi: 10.1063/1.3647092
di A. D’Angelo, K. Ardashev, C. Bade, O. Bartalini, V. Bellini, M. Blecher, J. P. Bocquet, M. Capogni, A. Caracappa, L. E. Casano, M. Castoldi, R. Di Salvo, A. Fantini, D. Franco, G. Gervino, F. Ghio, G. Giardina, C. Gibson, B. Girolami, A. Giusa, H. Glu, K. Hicks, S. Hoblit, A. Honig, T. Kageya, M. Khandaker, O. C. Kistner, S. Kizilgul, S. Kucuker, A. Lapikf, A. Lehmann, P. Levi Sandri, A. Lleres, M. Lowry, M. Lucas, J. Mahon, F. Mammoliti, G. Mandaglio, M. Manganaro, L. Miceli, D. Moricciani, A. Mushkarenkovf, V. Nedorezovf, B. Norum, M. Papb, B. Preedom, H. Seyfarthb, C. Randieri, D. Rebreyend, N. Rudnevf, G. Russo, A. Sandorfi, C. Schaerf, M. L. Sperduto, H. Stroher, M. C. Sutera, C. E. Thorn, A. Turingef, V. Vegna, C. S. Whisnanth, K. Wang, X. Wei (2011)
Abstract
The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.
How to get involved in IODP and what you gain as a scientist - presentation by David McInroy at the UKCCSRC Glacistore meeting "Impact of glacial advances and retreats on the strata overlying prospective North Sea CO2 storage sites", 27 February 2015
The Polarized Cosmic Hand: IXPE Observations of PSR B1509-58/MSH 15−52Sérgio Sacani
We describe IXPE polarization observations of the Pulsar Wind Nebula (PWN) MSH 15−52, the
‘Cosmic Hand’. We find X-ray polarization across the PWN, with B field vectors generally aligned
with filamentary X-ray structures. High significance polarization is seen in arcs surrounding the pulsar
and toward the end of the ‘jet’, with polarization degree P D > 70%, thus approaching the maximum
allowed synchrotron value. In contrast, the base of the jet has lower polarization, indicating a complex
magnetic field at significant angle to the jet axis. We also detect significant polarization from PSR
B1509−58 itself. Although only the central pulse-phase bin of the pulse has high individual significance,
flanking bins provide lower significance detections and, in conjunction with the X-ray image and radio
polarization, can be used to constrain rotating vector model solutions for the pulsar geometry.
Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the ...Sérgio Sacani
We present measurements of the polarization of X-rays in the 2–8 keV band from the nucleus of the radio galaxy
Centaurus A (Cen A), using a 100 ks observation from the Imaging X-ray Polarimetry Explorer (IXPE). Nearly
simultaneous observations of Cen A were also taken with the Swift, NuSTAR, and INTEGRAL observatories. No
statistically significant degree of polarization is detected with IXPE. These observations have a minimum
detectable polarization at 99% confidence (MDP99) of 6.5% using a weighted, spectral model-independent
calculation in the 2–8 keV band. The polarization angle ψ is consequently unconstrained. Spectral fitting across
three orders of magnitude in X-ray energy (0.3–400 keV) demonstrates that the SED of Cen A is well described by
a simple power law with moderate intrinsic absorption (NH ∼ 1023 cm−2) and a Fe Kα emission line, although a
second unabsorbed power law is required to account for the observed spectrum at energies below 2 keV. This
spectrum suggests that the reprocessing material responsible for this emission line is optically thin and distant from
the central black hole. Our upper limits on the X-ray polarization are consistent with the predictions of Compton
scattering, although the specific seed photon population responsible for the production of the X-rays cannot be
identified. The low polarization degree, variability in the core emission, and the relative lack of variability in the Fe
Kα emission line support a picture where electrons are accelerated in a region of highly disordered magnetic fields
surrounding the innermost jet.
Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43bSérgio Sacani
HotJupiters are amongthebest-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5–12µ 5–12µ 5–12µm with JWST’s Mid-Infrared Instrument (MIRI). 1524 ±35 1524 ±35 and 863±23 The spectra reveal a large day–night temperature contrast (with average brightness temperatures of 1524 ± 35 863 ±23 863 ±23Kelvin, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase curve shape and emission spectra strongly suggest the presence of nightside clouds which become optically thick to thermal emission at pressures greater than ∼100mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Con3trary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1–6 parts per million, depending on model assumptions).
Magnetic Structures and Turbulence in SN 1006 Revealed with Imaging X-Ray Pol...Sérgio Sacani
Young supernova remnants strongly modify the surrounding magnetic fields, which in turn play an essential role in
accelerating cosmic rays (CRs). The X-ray polarization measurements probe magnetic field morphology and
turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell
of SN 1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer. We found an average
polarization degree of 22.4% ± 3.5% and an average polarization angle of −45°. 4 ± 4°.5 (measured on the plane of
the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately
behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed,
similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray
emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is
much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the
remnant, favoring that CR-induced instabilities set the magnetic turbulence in SN 1006, and CR acceleration is
environment-dependent.
The NANOGrav 15 yr Data Set: Detector Characterization and Noise BudgetSérgio Sacani
Pulsar timing arrays (PTAs) are galactic-scale gravitational wave (GW) detectors. Each individual arm, composed
of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can
be used to extract low-frequency GW signals. We present a noise and sensitivity analysis to accompany the
NANOGrav 15 yr data release and associated papers, along with an in-depth introduction to PTA noise models. As
a first step in our analysis, we characterize each individual pulsar data set with three types of white-noise
parameters and two red-noise parameters. These parameters, along with the timing model and, particularly, a
piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the lowfrequency GW band we are searching. We tabulate information for all of the pulsars in this data release and present
some representative sensitivity curves. We then combine the individual pulsar sensitivities using a signal-to-noise
ratio statistic to calculate the global sensitivity of the PTA to a stochastic background of GWs, obtaining a
minimum noise characteristic strain of 7 × 10−15 at 5 nHz. A power-law-integrated analysis shows rough
agreement with the amplitudes recovered in NANOGrav’s 15 yr GW background analysis. While our
phenomenological noise model does not model all known physical effects explicitly, it provides an accurate
characterization of the noise in the data while preserving sensitivity to multiple classes of GW signals.
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.
Astrônomos, usando os dados do Telescópio Espacial de Raios-Gamma Fermi da NASA detectaram pistas de mudanças periódicas no brilho de uma chamada galáxia “ativa”, cujas emissões são alimentadas por um buraco negro gigante. Se confirmada, a descoberta marcaria a primeira emissão cíclica de raios-gamma com anos de duração, já detectada de qualquer galáxia, o que forneceria novas ideias sobre os processos físicos que ocorrem nas proximidades de um buraco negro.
“Observando muitos anos de dados obtidos pelo Large Area Telescope, o LAT, do Fermi, nós identificamos indicações de uma variação com aproximadamente dois anos de comprimento de raios-gamma emitidos pela galáxia conhecida como PG 1553+113”, disse Stefano Ciprini, que coordenou a equipe do Fermi no Centro de Dados Científicos, o ASDC, da Agência Espacial Italiana, em Roma. “Esse sinal é sutil, e dura menos do que 4 ciclos, assim, do mesmo modo que é algo espetacular de se ver é algo que precisa de mais observações”.
Buracos negros supermassivos com uma massa de milhões de vezes a massa do Sol, localizam-se no coração da maioria das galáxias, incluindo a nossa Via Láctea. Em cerca de 1% dessas galáxias, o buraco negro monstruoso, irradia energia equivalente à bilhões de vezes a energia do Sol, emissões que podem variar em escala de tempo de minutos a anos. Os astrônomos se referem a essas como sendo galáxias ativas.
Mais da metade das fontes de raios-gamma observadas pelo LAT do Fermi, são galáxias ativas, chamadas de blazars, como a PG 1553+113. À medida que a matéria cai em direção ao seu buraco negro supermassivo, algumas partículas subatômicas escapam numa velocidade próxima à velocidade da luz em um par de jatos apontados em direções opostas. O que faz um blazar tão brilhante é que um desses jatos de partículas podem estar diretamente apontados para nós.
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument StudySérgio Sacani
On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signicantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
The morphological diversity_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve em detalhes as unidades morfológicas do cometa Churyumov-Gerasimenko, classificadas pelos cientistas com as análises feitas nas imagens de alta resolução da sonda Rosetta da ESA.
Complete Photoproduction Experiments - 12th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, Virginia, USA, 31 May-4 June 2010. AIP Conference Proceedings, October 2011, Vol. 1374, pp. 17-22, ISSN: 0094-243X, doi: 10.1063/1.3647092
di A. D’Angelo, K. Ardashev, C. Bade, O. Bartalini, V. Bellini, M. Blecher, J. P. Bocquet, M. Capogni, A. Caracappa, L. E. Casano, M. Castoldi, R. Di Salvo, A. Fantini, D. Franco, G. Gervino, F. Ghio, G. Giardina, C. Gibson, B. Girolami, A. Giusa, H. Glu, K. Hicks, S. Hoblit, A. Honig, T. Kageya, M. Khandaker, O. C. Kistner, S. Kizilgul, S. Kucuker, A. Lapikf, A. Lehmann, P. Levi Sandri, A. Lleres, M. Lowry, M. Lucas, J. Mahon, F. Mammoliti, G. Mandaglio, M. Manganaro, L. Miceli, D. Moricciani, A. Mushkarenkovf, V. Nedorezovf, B. Norum, M. Papb, B. Preedom, H. Seyfarthb, C. Randieri, D. Rebreyend, N. Rudnevf, G. Russo, A. Sandorfi, C. Schaerf, M. L. Sperduto, H. Stroher, M. C. Sutera, C. E. Thorn, A. Turingef, V. Vegna, C. S. Whisnanth, K. Wang, X. Wei (2011)
Abstract
The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.
How to get involved in IODP and what you gain as a scientist - presentation by David McInroy at the UKCCSRC Glacistore meeting "Impact of glacial advances and retreats on the strata overlying prospective North Sea CO2 storage sites", 27 February 2015
The Polarized Cosmic Hand: IXPE Observations of PSR B1509-58/MSH 15−52Sérgio Sacani
We describe IXPE polarization observations of the Pulsar Wind Nebula (PWN) MSH 15−52, the
‘Cosmic Hand’. We find X-ray polarization across the PWN, with B field vectors generally aligned
with filamentary X-ray structures. High significance polarization is seen in arcs surrounding the pulsar
and toward the end of the ‘jet’, with polarization degree P D > 70%, thus approaching the maximum
allowed synchrotron value. In contrast, the base of the jet has lower polarization, indicating a complex
magnetic field at significant angle to the jet axis. We also detect significant polarization from PSR
B1509−58 itself. Although only the central pulse-phase bin of the pulse has high individual significance,
flanking bins provide lower significance detections and, in conjunction with the X-ray image and radio
polarization, can be used to constrain rotating vector model solutions for the pulsar geometry.
Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the ...Sérgio Sacani
We present measurements of the polarization of X-rays in the 2–8 keV band from the nucleus of the radio galaxy
Centaurus A (Cen A), using a 100 ks observation from the Imaging X-ray Polarimetry Explorer (IXPE). Nearly
simultaneous observations of Cen A were also taken with the Swift, NuSTAR, and INTEGRAL observatories. No
statistically significant degree of polarization is detected with IXPE. These observations have a minimum
detectable polarization at 99% confidence (MDP99) of 6.5% using a weighted, spectral model-independent
calculation in the 2–8 keV band. The polarization angle ψ is consequently unconstrained. Spectral fitting across
three orders of magnitude in X-ray energy (0.3–400 keV) demonstrates that the SED of Cen A is well described by
a simple power law with moderate intrinsic absorption (NH ∼ 1023 cm−2) and a Fe Kα emission line, although a
second unabsorbed power law is required to account for the observed spectrum at energies below 2 keV. This
spectrum suggests that the reprocessing material responsible for this emission line is optically thin and distant from
the central black hole. Our upper limits on the X-ray polarization are consistent with the predictions of Compton
scattering, although the specific seed photon population responsible for the production of the X-rays cannot be
identified. The low polarization degree, variability in the core emission, and the relative lack of variability in the Fe
Kα emission line support a picture where electrons are accelerated in a region of highly disordered magnetic fields
surrounding the innermost jet.
Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43bSérgio Sacani
HotJupiters are amongthebest-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5–12µ 5–12µ 5–12µm with JWST’s Mid-Infrared Instrument (MIRI). 1524 ±35 1524 ±35 and 863±23 The spectra reveal a large day–night temperature contrast (with average brightness temperatures of 1524 ± 35 863 ±23 863 ±23Kelvin, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase curve shape and emission spectra strongly suggest the presence of nightside clouds which become optically thick to thermal emission at pressures greater than ∼100mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Con3trary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1–6 parts per million, depending on model assumptions).
Magnetic Structures and Turbulence in SN 1006 Revealed with Imaging X-Ray Pol...Sérgio Sacani
Young supernova remnants strongly modify the surrounding magnetic fields, which in turn play an essential role in
accelerating cosmic rays (CRs). The X-ray polarization measurements probe magnetic field morphology and
turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell
of SN 1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer. We found an average
polarization degree of 22.4% ± 3.5% and an average polarization angle of −45°. 4 ± 4°.5 (measured on the plane of
the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately
behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed,
similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray
emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is
much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the
remnant, favoring that CR-induced instabilities set the magnetic turbulence in SN 1006, and CR acceleration is
environment-dependent.
The NANOGrav 15 yr Data Set: Detector Characterization and Noise BudgetSérgio Sacani
Pulsar timing arrays (PTAs) are galactic-scale gravitational wave (GW) detectors. Each individual arm, composed
of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can
be used to extract low-frequency GW signals. We present a noise and sensitivity analysis to accompany the
NANOGrav 15 yr data release and associated papers, along with an in-depth introduction to PTA noise models. As
a first step in our analysis, we characterize each individual pulsar data set with three types of white-noise
parameters and two red-noise parameters. These parameters, along with the timing model and, particularly, a
piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the lowfrequency GW band we are searching. We tabulate information for all of the pulsars in this data release and present
some representative sensitivity curves. We then combine the individual pulsar sensitivities using a signal-to-noise
ratio statistic to calculate the global sensitivity of the PTA to a stochastic background of GWs, obtaining a
minimum noise characteristic strain of 7 × 10−15 at 5 nHz. A power-law-integrated analysis shows rough
agreement with the amplitudes recovered in NANOGrav’s 15 yr GW background analysis. While our
phenomenological noise model does not model all known physical effects explicitly, it provides an accurate
characterization of the noise in the data while preserving sensitivity to multiple classes of GW signals.
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.
Astrônomos, usando os dados do Telescópio Espacial de Raios-Gamma Fermi da NASA detectaram pistas de mudanças periódicas no brilho de uma chamada galáxia “ativa”, cujas emissões são alimentadas por um buraco negro gigante. Se confirmada, a descoberta marcaria a primeira emissão cíclica de raios-gamma com anos de duração, já detectada de qualquer galáxia, o que forneceria novas ideias sobre os processos físicos que ocorrem nas proximidades de um buraco negro.
“Observando muitos anos de dados obtidos pelo Large Area Telescope, o LAT, do Fermi, nós identificamos indicações de uma variação com aproximadamente dois anos de comprimento de raios-gamma emitidos pela galáxia conhecida como PG 1553+113”, disse Stefano Ciprini, que coordenou a equipe do Fermi no Centro de Dados Científicos, o ASDC, da Agência Espacial Italiana, em Roma. “Esse sinal é sutil, e dura menos do que 4 ciclos, assim, do mesmo modo que é algo espetacular de se ver é algo que precisa de mais observações”.
Buracos negros supermassivos com uma massa de milhões de vezes a massa do Sol, localizam-se no coração da maioria das galáxias, incluindo a nossa Via Láctea. Em cerca de 1% dessas galáxias, o buraco negro monstruoso, irradia energia equivalente à bilhões de vezes a energia do Sol, emissões que podem variar em escala de tempo de minutos a anos. Os astrônomos se referem a essas como sendo galáxias ativas.
Mais da metade das fontes de raios-gamma observadas pelo LAT do Fermi, são galáxias ativas, chamadas de blazars, como a PG 1553+113. À medida que a matéria cai em direção ao seu buraco negro supermassivo, algumas partículas subatômicas escapam numa velocidade próxima à velocidade da luz em um par de jatos apontados em direções opostas. O que faz um blazar tão brilhante é que um desses jatos de partículas podem estar diretamente apontados para nós.
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument StudySérgio Sacani
On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signicantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
The morphological diversity_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve em detalhes as unidades morfológicas do cometa Churyumov-Gerasimenko, classificadas pelos cientistas com as análises feitas nas imagens de alta resolução da sonda Rosetta da ESA.
A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): JWST...Sérgio Sacani
We present the first results from the JWST program A SPectroscopic survey of biased halos In the Reionization Era
(ASPIRE). This program represents an imaging and spectroscopic survey of 25 reionization-era quasars and their
environments by utilizing the unprecedented capabilities of NIRCam Wide Field Slitless Spectroscopy (WFSS)
mode. ASPIRE will deliver the largest (~280 arcmin2) galaxy redshift survey at 3–4 μm among JWST Cycle 1
programs and provide extensive legacy values for studying the formation of the earliest supermassive black holes,
the assembly of galaxies, early metal enrichment, and cosmic reionization. In this first ASPIRE paper, we report
the discovery of a filamentary structure traced by the luminous quasar J0305–3150 and 10 [O III] emitters at
z = 6.6. This structure has a 3D galaxy overdensity of δgal = 12.6 over 637 cMpc3
, one of the most overdense
structures known in the early universe, and could eventually evolve into a massive galaxy cluster. Together with
existing VLT/MUSE and ALMA observations of this field, our JWST observations reveal that J0305–3150 traces
a complex environment where both UV-bright and dusty galaxies are present and indicate that the early evolution
of galaxies around the quasar is not simultaneous. In addition, we discovered 31 [O III] emitters in this field at other
redshifts, 5.3 < z < 6.7, with half of them situated at z ∼ 5.4 and 6.2. This indicates that star-forming galaxies, such
as [O III] emitters, are generally clustered at high redshifts. These discoveries demonstrate the unparalleled redshift
survey capabilities of NIRCam WFSS and the potential of the full ASPIRE survey data set.
An excess of massive stars in the local 30 Doradus starburstSérgio Sacani
The 30 Doradus star-forming region in the Large Magellanic Cloud is a nearby analog of large
star-formation events in the distant universe.We determined the recent formation history and
the initial mass function (IMF) of massive stars in 30 Doradus on the basis of spectroscopic
observations of 247 stars more massive than 15 solarmasses (M⊙).Themain episode of massive
star formation began about 8 million years (My) ago, and the star-formation rate seems to
have declined in the last 1 My.The IMF is densely sampled up to 200M⊙ and contains 32 ± 12%
more stars above 30 M⊙ than predicted by a standard Salpeter IMF. In the mass range of 15
to 200M⊙, the IMF power-law exponent is 1:90þ0:37
0:26, shallower than the Salpeter value of 2.35.
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 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 importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Toxic effects of heavy metals : Lead and Arsenicsanjana502982
Heavy metals are naturally occuring metallic chemical elements that have relatively high density, and are toxic at even low concentrations. All toxic metals are termed as heavy metals irrespective of their atomic mass and density, eg. arsenic, lead, mercury, cadmium, thallium, chromium, etc.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.