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Relative Alignments Between Magnetic Fields, Velocity Gradients, and Dust Emission Gradients in NGC 1333

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arXiv 2024年

作者： Chen, Michael Chun-Yuan Fissel, Laura M. Sadavoy, Sarah I. Rosolowsky, Erik Doi, Yasuo Arzoumanian, Doris Bastien, Pierre Coudé, Simon Di Francesco, James Friesen, Rachel Furuya, Ray S. Hwang, Jihye Inutsuka, Shu-Ichiro Johnstone, Doug Karoly, Janik Kwon, Jungmi Kwon, Woojin Le Gouellec, Valentin J.M. Liu, Hong-Li Mairs, Steve Onaka, Takashi Pattle, Kate Rawlings, Mark G. Tahani, Mehrnoosh Tamura, Motohide Wang, Jia-Wei Department of Physics Engineering Physics and Astronomy Queen’s University KingstonONK7L 3N6 Canada Department of Physics University of Alberta EdmontonABT6G 2E1 Canada Department of Earth Science and Astronomy The University of Tokyo 3-8-1 Komaba Meguro Tokyo153-8902 Japan National Astronomical Observatory of Japan Osawa 2-21-1 Mitaka Tokyo181-8588 Japan Université de Montréal Département de Physique 1375 Avenue Thérèse-Lavoie-Roux MontréalQCH2V 0B3 Canada Department of Earth Environment and Physics Worcester State University WorcesterMA01602 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States NRC Herzberg Astronomy and Astrophysics 5071 West Saanich Rd VictoriaBCV9E 2E7 Canada Department of Physics and Astronomy University of Victoria VictoriaBCV8P 5C2 Canada David A. Dunlap Department of Astronomy and Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Institute of Liberal Arts and Sciences Tokushima University Minami Jousanajima-machi 1-1 Tokushima770-8502 Japan Korea Astronomy and Space Science Institute 776 Daedeokdae-ro Yuseong-gu Daejeon34055 Korea Republic of University of Science and Technology Korea 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Department of Physics Graduate School of Science Nagoya University Furo-cho Chikusa-ku Nagoya464-8602 Japan Jeremiah Horrocks Institute University of Central Lancashire PrestonPR1 2HE United Kingdom Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Department of Earth Science Education Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of SNU Astronomy Research Center Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of NASA Ames Research Center Space Science and Astrobiology Division M.S. 245-6 Moffett FieldCA94035 United States NASA Postdoc

Magnetic fields play an important role in shaping and regulating star formation in molecular clouds. Here, we present one of the first studies examining the relative orientations between magnetic (B) fields and the dust emission, gas column density, and velocity centroid gradients on the 0.02 pc (core) scales, using the BISTRO and VLA+GBT observations of the NGC 1333 star-forming clump. We quantified these relative orientations using the Project Rayleigh Statistic (PRS) and found preferential global parallel alignment between the B field and dust emission gradients, consistent with large-scale studies with Planck. No preferential global alignments, however, are found between the B field and velocity gradients. Local PRS calculated for subregions defined by either dust emission or velocity coherence further revealed that the Bfield does not preferentially align with dust emission gradients in most emission-defined subregions, except in the warmest ones. The velocity-coherent structures, on the other hand, also showed no preferred B field alignments with velocity gradients, except for one potentially bubble-compressed region. Interestingly, the velocity gradient magnitude in NGC 1333 ubiquitously features prominent ripple-like structures that are indicative of magnetohydrodynamic (MHD) waves. Finally, we found B field alignments with the emission gradients to correlate with dust temperature and anticorrelate with column density, velocity dispersion, and velocity gradient magnitude. The latter two anticorrelations suggest that alignments between gas structures and B fields can be perturbed by physical processes that elevate velocity dispersion and velocity gradients, such as infall, accretions, and MHD waves. © 2024, CC BY.

关键词： Plasma magnetohydrodynamic waves

Evidence for the volatile-rich composition of a 1.5-R⊕ planet

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arXiv 2022年

作者： Piaulet, Caroline Benneke, Björn Almenara, Jose M. Dragomir, Diana Knutson, Heather A. Thorngren, Daniel Peterson, Merrin S. Crossfield, Ian J.M. Kempton, Eliza M.-R. Kubyshkina, Daria Howard, Andrew W. Angus, Ruth Isaacson, Howard Weiss, Lauren M. Beichman, Charles A. Fortney, Jonathan J. Fossati, Luca Lammer, Helmut McCullough, P.R. Morley, Caroline V. Wong, Ian Department of Physics Institute for Research on Exoplanets Université de Montréal MontrealQC Canada Université Grenoble Alpes CNRS IPAG Grenoble38000 France Department of Physics and Astronomy University of New Mexico 210 Yale Blvd NE AlbuquerqueNM87106 United States Division of Geological and Planetary Sciences California Institute of Technology PasadenaCA91125 United States Department of Astronomy & Astrophysics University of California Santa CruzCA95064 United States The University of Kansas Department of Physics and Astronomy Malott Room 1082 1251 Wescoe Hall Drive LawrenceKS66045 United States Department of Astronomy University of Maryland College ParkMD20742 United States Space Research Institute Austrian Academy of Sciences Schmiedlstrasse 6 Graz8042 Austria Department of Astronomy California Institute of Technology PasadenaCA91125 United States Department of Astrophysics American Museum of Natural History 200 Central Park West ManhattanNY10024 United States Center for Computational Astrophysics Flatiron Institute 162 5th Ave ManhattanNY10010 United States Department of Astronomy University of California - Berkeley BerkeleyCA94720 United States Department of Physics University of Notre Dame Notre DameIN46556 United States NASA Exoplanet Science Institute Caltech/IPAC PasadenaCA91125 United States The William H. Miller III Department of Physics and Astronomy Johns Hopkins University BaltimoreMD21218 United States Space Telescope Science Institute 3700 San Martin Dr. BaltimoreMD21218 United States Department of Astronomy University of Texas AustinTX78712 United States NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States NASA Postdoctoral Program Fellow United States

The population of planets smaller than approximately 1.7 R⊕ is widely interpreted as consisting of rocky worlds, generally referred to as super-Earths. This picture is largely corroborated by radial-velocity (RV) mass measurements for close-in super-Earths but lacks constraints at lower insolations. Here we present the results of a detailed study of the Kepler-138 system using 13 Hubble and Spitzer transit observations of the warm-temperate 1.51±0.04 R⊕ planet Kepler-138 d (Teq,AB=0.3 ≈ 350 K) combined with new Keck/HIRES RV measurements of its host star. We find evidence for a volatile-rich water world nature of Kepler-138 d, with a large fraction of its mass contained in a thick volatile layer. This finding is independently supported by transit timing variations, RV observations (Md = 2.1−0.7+0.6 M⊕), as well as the flat optical/IR transmission spectrum. Quantitatively, we infer a composition of 11−4+3% volatiles by mass or ∼ 51% by volume, with a 2000 km deep water mantle and atmosphere on top of a core with an Earth-like silicates/iron ratio. Any hypothetical hydrogen layer consistent with the observations (⊕) would have swiftly been lost on a ∼ 10 Myr timescale. The bulk composition of Kepler-138 d therefore resembles those of the icy moons rather than the terrestrial planets in the solar system. We conclude that not all super-Earth-sized planets are rocky worlds, but that volatile-rich water worlds exist in an overlapping size regime, especially at lower insolations. Finally, our photodynamical analysis also reveals that Kepler-138 c (Rc = 1.51 ± 0.04 R⊕, Mc = 2.3−0.5+0.6 M⊕) is a slightly warmer twin of Kepler-138 d, i.e., another water world in the same system, and we infer the presence of Kepler-138 e, a likely non-transiting planet at the inner edge of the habitable zone. © 2022, CC BY.

关键词： Silicates

Spectral and timing analysis of NuSTAR and Swift/XRT observations of the X-Ray transient MAXI J0637-430

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arXiv 2021年

作者： Lazar, Hadar Tomsick, John A. Pike, Sean N. Bachetti, Matteo Buisson, Douglas J.K. Connors, Riley M.T. Fabian, Andrew C. Fuerst, Felix García, Javier A. Hare, Jeremy Jiang, Jiachen Shaw, Aarran W. Walton, Dominic J. Space Sciences Laboratory University of California 7 Gauss Way BerkeleyCA94720-7450 United States Cahill Center for Astronomy and Astrophysics California Institute of Technology PasadenaCA91125 United States INAF - Osservatorio Astronomico di Cagliari via della Scienza 5 SelargiusI-09047 Italy Department of Physics and Astronomy University of Southampton Highfield SouthamptonSO17 1BJ United Kingdom Institute of Astronomy University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom European Space Astronomy Centre E-28691 Villanueva de la Cañada Madrid Spain Dr. Karl Remeis-Observatory Erlangen Centre for Astroparticle Physics Sternwartstr. 7 Bamberg96049 Germany NASA Goddard Space Flight Center GreenbeltMD20771 United States NASA Postdoctoral Program Fellow Department of Astronomy Tsinghua University Shuangquing Road 30 Beijing100084 China Department of Physics University of Nevada RenoNV89557 United States

We present results for the first observed outburst from the transient X-ray binary source MAXI J0637−430. This study is based on eight observations from the Nuclear Spectroscopic Telescope Array (NuSTAR) and six observations from the Neil Gehrels Swift Observatory X-Ray Telescope (Swift/XRT) collected from 2019 November 19 to 2020 April 26 as the 3–79 keV source flux declined from 8.2 × 10−10 to 1.4 × 10−12 erg cm−2 s−1. We see the source transition from a soft state with a strong disk-blackbody component to a hard state dominated by a power-law or thermal Comptonization component. NuSTAR provides the first reported coverage of MAXI J0637−430 above 10 keV, and these broadband spectra show that a two-component model does not provide an adequate description of the soft state spectrum. As such, we test whether blackbody emission from the plunging region could explain the excess emission. As an alternative, we test a reflection model that includes a physical Comptonization continuum. Finally, we also test a spectral component based on reflection of a blackbody illumination spectrum, which can be interpreted as a simple approximation to the reflection produced by returning disk radiation due to the bending of light by the strong gravity of the black hole. We discuss the physical implications of each scenario and demonstrate the value of constraining the source distance. Copyright © 2021, The Authors. All rights reserved.

关键词： Timing circuits

NEOMOD: A New Orbital Distribution Model for Near Earth Objects

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arXiv 2023年

作者： Nesvorný, David Deienno, Rogerio Bottke, William F. Jedicke, Robert Naidu, Shantanu Chesley, Steven R. Chodas, Paul W. Granvik, Mikael Vokrouhlický, David Brož, Miroslav Morbidelli, Alessandro Christensen, Eric Bolin, Bryce T. Department of Space Studies Southwest Research Institute 1050 Walnut St. Suite 300 BoulderCO80302 United States Institute for Astronomy University of Hawaii 2680 Woodlawn Drive HonoluluHI96822-1839 United States Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Dr PasadenaCA91109 United States Department of Earth and Space Sciences University of California 595 Charles Young Drive East 5656 Geology Building Los AngelesCA90095 United States Department of Physics University of Helsinki P.O. Box 64 FI-00014 Finland Asteroid Engineering Laboratory Luleå University of Technology Box 848 KirunaSE-981 28 Sweden Institute of Astronomy Charles University V Holešovičkách 2 Prague 8CZ–18000 Czech Republic Laboratoire Lagrange UMR7293 Université Côte d’Azur CNRS Observatoire de la Côte d’Azur Bouldervard de l’Observatoire Nice06304 Cedex 4 France Lunar and Planetary Laboratory The University of Arizona 1629 E. University Blvd. TucsonAZ85721-0092 United States Division of Physics Mathematics and Astronomy California Institute of Technology PasadenaCA91125 United States Infrared Processing and Analysis Center California Institute of Technology PasadenaCA91125 United States NASA Postdoctoral Program Fellow Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States

Near Earth Objects (NEOs) are a transient population of small bodies with orbits near or in the terrestrial planet region. They represent a mid-stage in the dynamical cycle of asteroids and comets, which starts with their removal from the respective source regions – the main belt and trans-Neptunian scattered disk – and ends as bodies impact planets, disintegrate near the Sun, or are ejected from the Solar System. Here we develop a new orbital model of NEOs by numerically integrating asteroid orbits from main belt sources and calibrating the results on observations of the Catalina Sky Survey. The results imply a size-dependent sampling of the main belt with the ν6 and 3:1 resonances producing ' 30% of NEOs with absolute magnitudes H = 15 and ' 80% of NEOs with H = 25. Hence, the large and small NEOs have different orbital distributions. The inferred flux of H −4 au Myr−1 for diameter D = 1 km and semimajor axis a = 2.5 au). This implies obliquities θ ' 0◦ for a ◦ for a > 2.5 au, both in the immediate neighborhood of the resonance (the same applies to other resonances as well). We confirm the size-dependent disruption of asteroids near the Sun found in previous studies. An interested researcher can use the publicly available NEOMOD Simulator to generate user-defined samples of NEOs from our model. Copyright © 2023, The Authors. All rights reserved.

关键词： Asteroids

A detailed time-resolved and energy-resolved spectro-polarimetric study of bright GRBs detected by AstroSat CZTI in its first year of operation

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arXiv 2024年

作者： Gupta, Rahul Pandey, S.B. Gupta, S. Chattopadhayay, T. Bhattacharya, D. Bhalerao, V. Castro-Tirado, A.J. Valeev, A. Ror, A.K. Sharma, V. Racusin, J. Aryan, A. Iyyani, S. Vadawale, S. Astrophysics Science Division NASA Goddard Space Flight Center Mail Code 661 GreenbeltMD20771 United States NASA Postdoctoral Program Manora Peak Nainital263002 India Bhabha Atomic Research Center Maharashtra Mumbai400094 India Homi Bhabha National Institute Maharashtra Mumbai400094 India Kavli Institute of Particle Astrophysics and Cosmology Stanford University 452 Lomita Mall StanfordCA94305 United States Department of Physics Ashoka University Haryana Sonipat131029 India Indian Institute of Technology Bombay Powai Maharashtra Mumbai400076 India Glorieta de la Astronomía s/n GranadaE-18008 Spain Departamento de Ingeniería de Sistemas y Automática Escuela de Ingenierías Universidad de Málaga C. Dr. Ortiz Ramos sn MálagaE-29071 Spain Special Astrophysical Observatory of Russian Academy of Sciences Nizhniy Arkhyz Russia University of Maryland Baltimore County BaltimoreMD21250 United States Center for Research and Exploration in Space Science and Technology NASA/GSFC GreenbeltMD20771 United States Graduate Institute of Astronomy National Central University 300 Jhongda Road Jhongli32001 Taiwan Indian Institute of Science Education and Research Kerala Thiruvananthapuram695551 India Physical Research Laboratory Thaltej Gujarat Ahmedabad380009 India

The radiation mechanism underlying the prompt emission remains unresolved and can be resolved using a systematic and uniform time-resolved spectro-polarimetric study. In this paper, we investigated the spectral, temporal, and polarimetric characteristics of five bright GRBs using archival data from AstroSat CZTI, Swift BAT, and Fermi GBM. These bright GRBs were detected by CZTI in its first year of operation, and their average polarization characteristics have been published in Chattopadhyay et al. (2022). In the present work, we examined the time-resolved (in 100-600 keV) and energyresolved polarization measurements of these GRBs with an improved polarimetric technique such as increasing the effective area and bandwidth (by using data from low-gain pixels), using an improved event selection logic to reduce noise in the double events and extend the spectral bandwidth. In addition, we also separately carried out detailed time-resolved spectral analyses of these GRBs using empirical and physical synchrotron models. By these improved time-resolved and energy-resolved spectral and polarimetric studies (not fully coupled spectro-polarimetric fitting), we could pin down the elusive prompt emission mechanism of these GRBs. Our spectro-polarimetric analysis reveals that GRB 160623A, GRB 160703A, and GRB 160821A have Poynting flux-dominated jets. On the other hand, GRB 160325A and GRB 160802A have baryonic-dominated jets with mild magnetization. Furthermore, we observe a rapid change in polarization angle by ∼ 90 degrees within the main pulse of very bright GRB 160821A, consistent with our previous results. Our study suggests that the jet composition of GRBs may exhibit a wide range of magnetization, which can be revealed by utilizing spectro-polarimetric investigations of the bright GRBs. Copyright © 2024, The Authors. All rights reserved.

关键词： Polarimeters

Multi-wavelength observations of 2hwc j1928+177: Dark accelerator or new tev gamma-ray binary?

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arXiv 2020年

作者： Mori, Kaya An, Hongjun Feng, Qi Malone, Kelly Prado, Raul R. Schutt, Yve E. Dingus, Brenda L. Gotthelf, E.V. Hailey, Charles J. Hare, Jeremy Kargaltsev, Oleg Mukherjee, Reshmi Columbia Astrophysics Laboratory Columbia University New YorkNY10027 United States Department of Astronomy and Space Science Chungbuk National University Cheongju28644 Korea Republic of Physics Department Columbia University New YorkNY10027 United States Los Alamos National Laboratory Los AlamosNM United States DESY Platanenallee 6 Zeuthen15738 Germany NASA Postdoctoral Program Fellow NASA Goddard Space Flight Center GreenbeltMD20771 United States Department of Physics George Washington University 725 21st Street NW WashingtonDC20052 United States Department of Physics and Astronomy Barnard College Columbia University NY10027 United States

2HWC J1928+177 is a Galactic TeV gamma-ray source detected by the High Altitude Water Cherenkov (HAWC) Observatory up to ∼ 56 TeV. The HAWC source, later confirmed by H.E.S.S., still remains unidentified as a dark accelerator since there is no apparent supernova remnant or pulsar wind nebula detected in the lower energy bands. The radio pulsar PSR J1928+1746, coinciding with the HAWC source position, has no X-ray counterpart. Our SED modeling shows that inverse Compton scattering in the putative pulsar wind nebula can account for the TeV emission only if the unseen nebula is extended beyond r ∼ 40. Alternatively, TeV gamma rays may be produced by hadronic interactions between relativistic protons from an undetected supernova remnant associated with the radio pulsar and a nearby molecular cloud G52.9+0.1. NuSTAR and Chandra observations detected a variable X-ray point source within the HAWC error circle, potentially associated with a bright IR source. The X-ray spectra can be fitted with an absorbed power-law model with NH = (9 ± 3) × 1022 cm−2 and ΓX = 1.6 ± 0.3 and exhibit long-term X-ray flux variability over the last decade. If the X-ray source, possibly associated with the IR source (likely an O star), is the counterpart of the HAWC source, it may be a new TeV gamma-ray binary powered by collisions between the pulsar wind and stellar wind. Follow-up X-ray observations are warranted to search for diffuse X-ray emission and determine the nature of the HAWC source. Copyright © 2020, The Authors. All rights reserved.

关键词： Gamma rays

QUASI-PERIODICITY OF SUPERMASSIVE BINARY BLACK HOLE ACCRETION APPROACHING MERGER

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arXiv 2019年

作者： Bowen, Dennis B. Mewes, Vassilios Noble, Scott C. Avara, Mark Campanelli, Manuela Krolik, Julian H. Center for Theoretical Astrophysics and X Computational Physics Los Alamos National Laboratory Los AlamosNM87545 United States Center for Computational Relativity and Gravitation Rochester Institute of Technology RochesterNY14623 Department of Physics and Engineering Physics University of Tulsa TulsaOK74104 NASA Postdoctoral Program Senior Fellow Goddard Space Flight Center GreenbeltMD20771 Department of Physics and Astronomy Johns Hopkins University BaltimoreMD21218

In this paper we continue the first ever study of magnetized mini-disks coupled to circumbinary accretion in a supermassive binary black hole (SMBBH) approaching merger reported in Bowen et al. (2018). We extend this simulation from 3 to 12 binary orbital periods. We find that relativistic SMBBH accretion acts as a resonant cavity, where quasi-periodic oscillations tied to the the frequency at which the black hole’s orbital phase matches a non-linear m = 1 density feature, or "lump", in the circumbinary accretion disk permeate the system. The rate of mass accretion onto each of the mini-disks around the black holes is modulated at the beat frequency between the binary frequency and the lump’s mean orbital frequency, i.e., Ωbeat = Ωbin − Ω¯lump, while the total mass accretion rate of this equal-mass binary is modulated at two different frequencies, ∼> Ω¯lump and ≈ 2Ωbeat. The instantaneous rotation rate of the lump itself is also modulated at two frequencies close to the modulation frequencies of the total accretion rate, Ω¯lump and 2Ωbeat. Because of the compact nature of the mini-disks in SMBBHs approaching merger, the inflow times within the mini-disks are comparable to the period on which their mass-supply varies, so that their masses—and the accretion rates they supply to their black holes—are strongly modulated at the same frequency. In essence, the azimuthal symmetry of the circumbinary disk is broken by the dynamics of orbits near a binary, and this m = 1 asymmetry then drives quasi-periodic variation throughout the system, including both accretion and disk-feeding. In SMBBHs approaching merger, such time variability could introduce distinctive, increasingly rapid, fluctuations in their electromagnetic emission. Copyright © 2019, The Authors. All rights reserved.

关键词： Merging

Characterising a World Within the Hot Neptune Desert: Transit Observations of LTT 9779 b with HST WFC3

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arXiv 2023年

作者： Edwards, Billy Changeat, Quentin Tsiaras, Angelos Allan, Andrew Behr, Patrick Hagey, Simone R. Himes, Michael D. Ma, Sushuang Stassun, Keivan G. Thomas, Luis Thompson, Alexandra Boley, Aaron Booth, Luke Bouwman, Jeroen France, Kevin Lowson, Nataliea Meech, Annabella Phillips, Caprice L. Vidotto, Aline A. Yip, Kai Hou Bieger, Michelle Gressier, Amélie Janin, Estelle Jiang, Ing-Guey Leonardi, Pietro Sarkar, Subhajit Skaf, Nour Taylor, Jake Yang, Ming Ward-Thompson, Derek SRON Netherlands Institute for Space Research Niels Bohrweg 4 LeidenNL-2333 CA Netherlands BaltimoreMD21218 United States INAF Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze50125 Italy Leiden Observatory Leiden University PO Box 9513 Leiden2300 RA Netherlands Laboratory for Atmospheric and Space Physics University of Colorado Boulder BoulderCO80303 United States The University of British Columbia 6224 Agricultural Road VancouverBCV6T 1Z1 Canada Planetary Sciences Group Department of Physics University of Central Florida OrlandoFL United States NASA Postdoctoral Program Fellow NASA Goddard Space Flight Center GreenbeltMD United States Department of Physics and Astronomy University College London Gower Street LondonWC1E 6BT United Kingdom Department of Physics and Astronomy Vanderbilt University NashvilleTN37235 United States Universitäts-Sternwarte München Scheinerstr. 1 MünchenD-81679 Germany Max-Planck-Institut für extraterrestrische Physik Giessenbachstrasse 1 GarchingD-85748 Germany School of Physics and Astronomy Cardiff University United Kingdom Max-Planck-Institut für Astronomie Königstuhl 17 Heidelberg69117 Germany Centre for Astrophysics University of Southern Queensland 499-565 West Street ToowoombaQLD4350 Australia Department of Physics University of Oxford Denys Wilkinson Building OxfordOX1 3RH United Kingdom Department of Astronomy The Ohio State University 100 W 18th Ave ColumbusOH43210 United States College of Engineering Mathematics and Physical Sciences University of Exeter North Park Road Exeter United Kingdom Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Arizona State University PO Box 871404 TempeAZ85287-1404 United States Department of Physics Institute of Astronomy National Tsing Hua University Hsinchu30013 Taiwan Dipartimento di Fisica Università di Trento Via Sommarive 14 Povo38123 Italy Dipartimento di Fisica e Astronomia Univers

We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot Neptune desert, that has been observed with HST WFC3 G102 and G141. The combined transmission spectrum, which covers 0.8 - 1.6 µm, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H2O, CO2 and FeH with a significance of 3.1 σ, 2.4 σ and 2.1 σ, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 µm Helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which is not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyman α. © 2023, CC BY.

关键词： Iron compounds

The LBT Satellites of Nearby Galaxies Survey (LBT-SONG): The satellite population of NGC 628

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arXiv 2020年

作者： Davis, A. Bianca Nierenberg, Anna M. Peter, Annika H.G. Garling, Christopher T. Greco, Johnny P. Kochanek, Christopher S. Utomo, Dyas Casey, Kirsten Pogge, Richard W. Roberts, Daniella Sand, David J. Sardone, Amy Department of Physics Ohio State University 191 W. Woodruff Ave. ColumbusOH43210 United States Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States Center for Cosmology and Astroparticle Physics Ohio State University 191 W. Woodruff Ave. ColumbusOH43210 United States Jet Propulsion Laboratory California Institute of Technology NASA Postdoctoral Program Steward Observatory University of Arizona 933 North Cherry Avenue Rm. N204 TucsonAZ85721-0065 United States NSF Astronomy and Astrophysics

We present the first satellite system of the Large Binocular Telescope Satellites Of Nearby Galaxies Survey (LBT-SONG), a survey to characterize the close satellite populations of Large Magellanic Cloud to Milky Way-mass, star-forming galaxies in the Local Volume. In this paper, we describe our satellite finding and completeness measurement methodology and apply this framework to NGC 628, an isolated galaxy with 1/4 the stellar mass of the Milky Way. We present two new dwarf satellite galaxy candidates: NGC 628 dwA, and dwB with MV = −12.2 and −7.7, respectively. NGC 628 dwA is a classical dwarf while NGC 628 dwB is a low-luminosity galaxy that appears to have been quenched after reionization. Completeness corrections indicate that the presence of these two satellites is consistent with CDM predictions. The satellite colors indicate that the galaxies are neither actively star-forming nor do they have the purely ancient stellar populations characteristic of ultrafaint dwarfs. Instead, and consistent with our previous work on the NGC 4214 system, they show signs of recent quenching, further indicating that environmental quenching can play a role in modifying satellite populations even for hosts smaller than the Milky Way. Copyright © 2020, The Authors. All rights reserved.

关键词： Galaxies