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The GAPS Programme at TNG L TOI-4515 b: An eccentric warm Jupiter orbiting a 1.2 Gyr-old G-star

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arXiv 2023年

作者： Carleo, I. Malavolta, L. Desidera, S. Nardiello, D. Wang, S. Turrini, D. Lanza, A.F. Baratella, M. Marzari, F. Benatti, S. Biazzo, K. Bieryla, A. Brahm, R. Bonavita, M. Collins, K.A. Hellier, C. Locci, D. Hobson, M.J. Maggio, A. Mantovan, G. Pinamonti, S. Messina, M. Rodriguez, J.E. Sozzetti, A. Stassun, K. Wang, X.Y. Ziegler, C. Damasso, M. Giacobbe, P. Murgas, F. Parviainen, H. Andreuzzi, G. Barkaoui, K. Berlind, P. Bignamini, A. Borsa, F. Briceno, C. Brogi, M. Cabona, L. Calkins, M.L. Capuzzo-Dolcetta, R. Cecconi, M. Colon, K.D. Cosentino, R. Dragomir, D. Esquerdo, G.A. Henning, T. Ghedina, A. Goeke, R.F. Gratton, R. Grau Horta, F. Gupta, A.F. Jenkins, J.M. Jordan, A. Knapic, C. Latham, D.W. Mireles, I. Law, N. Lorenzi, V. Lund, M.B. Maldonado, J. Mann, A.W. Molinari, E. Palle, E. Paegert, M. Pedani, M. Quinn, S.N. Scandariato, G. Seager, S. Winn, J.N. Wohler, B. Zingales, T. Calle Via Lactea s/n Tenerife La Laguna38200 Spain Tenerife La Laguna38206 Spain INAF - Osservatorio Astrofisico di Torino Via Osservatorio 20 Pino TorineseI-10025 Italy Dipartimento di Fisica e Astronomia "Galileo Galilei" Universita di Padova Vicolo dellOsservatorio 3 PadovaI-35122 Italy INAF - Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5 PadovaI-35122 Italy Astronomy Department Indiana University BloomingtonIN47405-7105 United States INAF - Osservatorio Astrofisico di Catania Via S. Sofia 78 CataniaI-95123 Italy An der Sternwarte 16 PotsdamD-14482 Germany INAF - Osservatorio Astronomico di Palermo Piazza del Parlamento1 PalermoI-90134 Italy Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Facultad de Ingeniera y Ciencias Universidad Adolfo Ibanez Av. Diagonal las Torres 2640 Penalolen Santiago Chile Millennium Institute for Astrophysics Chile Data Observatory Foundation Chile SUPA Institute for Astronomy University of Edinburgh Blackford Hill EdinburghEH9 3HJ United Kingdom Astrophysics Group Keele University Staffs ST5 5BG United Kingdom Max-Planck-Institut fur Astronomie Konigstuhl 17 Heidelberg69117 Germany Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Physics & Astronomy Vanderbilt University NashvilleTN United States Department of Physics Engineering and Astronomy Stephen F. Austin State University 1936 North St. NacogdochesTX75962 United States Fundacion Galileo Galilei-INAF Rambla Jose Ana Fernandez Perez 7 TF Brena Baja38712 Spain INAF - Osservatorio Astronomico di Roma Via Frascati 33 Monte Porzio Catone00078 Italy Astrobiology Research Unit Universite de Liege 19C Allee du 6 Aout Liege4000 Belgium Department of Earth Atmospheric and Planetary Science Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge

Context. Different theories have been developed to explain the origins and properties of close-in giant planets, but none of them alone can explain all of the properties of the warm Jupiters (WJs, Porb = 10 - 200 days). One of the most intriguing characteristics of WJs is that they have a wide range of orbital eccentricities, challenging our understanding of their formation and evolution. Aims. The investigation of these systems is crucial in order to put constraints on formation and evolution theories. TESS is providing a significant sample of transiting WJs around stars bright enough to allow spectroscopic follow-up studies. Methods. We carried out a radial velocity (RV) follow-up study of the TESS candidate TOI-4515 b with the high-resolution spectrograph HARPSN in the context of the GAPS project, the aim of which is to characterize young giant planets, and the TRES and FEROS spectrographs. We then performed a joint analysis of the HARPS-N, TRES, FEROS, and TESS data in order to fully characterize this planetary system. Results. We find that TOI-4515 b orbits a 1.2 Gyr-old G-star, has an orbital period of Pb = 15.266446 ± 0.000013 days, a mass of Mb = 2.01 ± 0.05 MJ, and a radius of Rb = 1.09 ± 0.04 RJ. We also find an eccentricity of e = 0.46 ± 0.01, placing this planet among the WJs with highly eccentric orbits. As no additional companion has been detected, this high eccentricity might be the consequence of past violent scattering events. Copyright © 2023, The Authors. All rights reserved.

关键词： Stars

Three Saturn-mass planets transiting F-type stars revealed with TESS and HARPS

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arXiv 2023年

作者： Psaridi, Angelica Bouchy, François Lendl, Monika Akinsanmi, Babatunde Stassun, Keivan G. Smalley, Barry Armstrong, David J. Howard, Saburo Ulmer-Moll, Solène Grieves, Nolan Barkaoui, Khalid Rodriguez, Joseph E. Bryant, Edward M. Suárez, Olga Guillot, Tristan Evans, Phil Attia, Omar Wittenmyer, Robert A. Yee, Samuel W. Collins, Karen A. Zhou, George Galland, Franck Parc, Léna Udry, Stéphane Figueira, Pedro Ziegler, Carl Mordasini, Christoph Winn, Joshua N. Seager, Sara Jenkins, Jon M. Twicken, Joseph D. Brahm, Rafael Jones, Matías I. Abe, Lyu Addison, Brett Briceño, César Briegal, Joshua T. Collins, Kevin I. Daylan, Tansu Eigmüller, Phillip Furesz, Gabor Guerrero, Natalia M. Hagelberg, Janis Heitzmann, Alexis Hounsell, Rebekah Huang, Chelsea X. Krenn, Andreas Law, Nicholas M. Mann, Andrew W. McCormac, James Mékarnia, Djamel Mounzer, Dany Nielsen, Louise D. Osborn, Ares Reinarz, Yared Sefako, Ramotholo R. Steiner, Michal Strøm, Paul A. Triaud, Amaury H.M.J. Vanderspek, Roland Vanzi, Leonardo Vines, Jose I. Watson, Christopher A. Wright, Duncan J. Zapata, Abner Observatoire de Genève Université de Genève Chemin Pegasi 51 Versoix1290 Switzerland Vanderbilt University Department of Physics & Astronomy 6301 Stevenson Center Lane NashvilleTN37235 United States Astrophysics Group Keele University StaffordshireST5 5BG United Kingdom Department of Physics University of Warwick Gibbet Hill Road CoventryCV4 7AL United Kingdom Centre for Exoplanets and Habitability University of Warwick Gibbet Hill Road CoventryCV4 7AL United Kingdom Université Côte d’Azur Observatoire de la Côte d’Azur CNRS Laboratoire Lagrange Bd de l’Observatoire CS 34229 Nicecedex 4 06304 France Physikalisches Institut University of Bern Gesellschaftsstrasse 6 Bern3012 Switzerland Astrobiology Research Unit Université de Liège 19C Allée du 6 Août Liège4000 Belgium Department of Earth Atmospheric and Planetary Science Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Calle Vía Láctea s/n Tenerife La Laguna38200 Spain Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Mullard Space Science Laboratory University College London Holmbury St Mary Surrey DorkingRH5 6NT United Kingdom El Sauce Observatory Coquimbo Province Chile University of Southern Queensland Centre for Astrophysics West Street ToowoombaQLD4350 Australia Department of Astrophysical Sciences Princeton University PrincetonNJ08544 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States University of Grenoble Alpes CNRS IPAG GrenobleF-38000 France Instituto de Astrofísica e Ciências do Espaço Universidade do Porto CauP Rua das Estrelas Porto4150-762 Portugal Department of Physics Engineering and Astronomy Stephen F. Austin State University 1936 North St NacogdochesTX75962 United States Department of Physics Kavli Institute for Astrophysics and Space Research

While the sample of confirmed exoplanets continues to grow, the population of transiting exoplanets around early-type stars is still limited. These planets allow us to investigate the planet properties and formation pathways over a wide range of stellar masses and study the impact of high irradiation on hot Jupiters orbiting such stars. We report the discovery of TOI-615b, TOI-622b, and TOI-2641b, three Saturn-mass planets transiting main sequence, F-type stars. The planets were identified by the Transiting Exoplanet Survey Satellite (TESS) and confirmed with complementary ground-based and radial velocity observations. TOI-615b is a highly irradiated (∼1277 F⊕) and bloated Saturn-mass planet (formula presented) in a 4.66 day orbit transiting a 6850 K star. TOI-622b has a radius of (formula presented) RJup and a mass of (formula presented) in a 6.40 day orbit. Despite its high insolation flux (∼600 F⊕), TOI-622b does not show any evidence of radius inflation. TOI-2641b is a (formula presented) planet in a 4.88 day orbit with a grazing transit (formula presented) that results in a poorly constrained radius of (formula presented). Additionally, TOI-615b is considered attractive for atmospheric studies via transmission spectroscopy with ground-based spectrographs and JWST. Future atmospheric and spin-orbit alignment observations are essential since they can provide information on the atmospheric composition, formation, and migration of exoplanets across various stellar types. © 2023, CC BY.

关键词： Stars

Classical novae at radio wavelengths

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arXiv 2021年

作者： Chomiuk, Laura Linford, Justin D. Aydi, Elias Bannister, Keith W. Krauss, Miriam I. Mioduszewski, Amy J. Mukai, Koji Nelson, Thomas J. Rupen, Michael P. Ryder, Stuart D. Sokoloski, Jennifer L. Sokolovsky, Kirill V. Strader, Jay Filipović, Miroslav D. Finzell, Tom Kawash, Adam Kool, Erik C. Metzger, Brian D. Nyamai, Miriam M. Ribeiro, Valério A.R.M. Roy, Nirupam Urquhart, Ryan Weston, Jennifer Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States National Radio Astronomy Observatory P.O. Box O SocorroNM87801 United States CSIRO Astronomy and Space Science PO Box 76 EppingNSW1710 Australia Pasadena City College 1570 E. Colorado Blvd. PasadenaCA91106 United States Center for Space Science and Technology University of Maryland Baltimore County BaltimoreMD21250 United States CRESST and X-ray Astrophysics Laboratory NASA/GSFC GreenbeltMD20771 United States Department of Physics and Astronomy University of Pittsburgh 3941 OHara St. PittsburghPA15260 United States Herzberg Institute of Astrophysics National Research Council of Canada PentictonBCV2A 6J9 Canada Department of Physics and Astronomy Macquarie University NSW2109 Australia Macquarie University Research Centre for Astronomy Astrophysics & Astrophotonics SydneyNSW2109 Australia Columbia Astrophysics Laboratory Columbia University New YorkNY United States Sternberg Astronomical Institute Moscow State University Universitetskii pr. 13 Moscow119992 Russia Western Sydney University Locked Bag 1797 Penrith South DCNSW2751 Australia Department of Computational Math Science and Engineering Michigan State University East LansingMI48824 United States The Oskar Klein Centre Department of Astronomy Stockholm University AlbaNova StockholmSE-106 91 Sweden Center for Computational Astrophysics Flatiron Institute 162 W. 5th Avenue New YorkNY10011 United States Department of Astronomy University of Cape Town Private Bag X3 Rondebosch7701 South Africa Instituto de Telecomunicações Campus Universitário de Santiago Aveiro3810-193 Portugal Department of Physics Indian Institute of Science Bangalore560012 India Federated IT 1201 Wilson Blvd 27th Floor ArlingtonVA22209 United States

We present radio observations (1–40 GHz) for 36 classical novae, representing data from over five decades compiled from the literature, telescope archives, and our own programs. Our targets display a striking diversity in their optical parameters (e.g., spanning optical fading timescales, t2 = 1–263 days), and we find a similar diversity in the radio light curves. Using a brightness temperature analysis, we find that radio emission from novae is a mixture of thermal and synchrotron emission, with non-thermal emission observed at earlier times. We identify high brightness temperature emission (TB > 5 × 104 K) as an indication of synchrotron emission in at least 9 (25%) of the novae. We find a class of synchrotron-dominated novae with mildly evolved companions, exemplified by V5589 Sgr and V392 Per, that appear to be a bridge between classical novae with dwarf companions and symbiotic binaries with giant companions. Four of the novae in our sample have two distinct radio maxima (the first dominated by synchrotron and the later by thermal emission), and in four cases the early synchrotron peak is temporally coincident with a dramatic dip in the optical light curve, hinting at a common site for particle acceleration and dust formation. We publish the light curves as tables and encourage use of these data by the broader community in multi-wavelength studies and modeling efforts. © 2021, CC BY.

关键词： Radio astronomy

Young, blue, and isolated stellar systems in the Virgo Cluster I. 2-D Optical spectroscopy

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arXiv 2022年

作者： Bellazzini, Michele Magrini, Laura Jones, Michael G. Sand, David J. Beccari, Giacomo Cresci, Giovanni Spekkens, Kristine Karunakaran, Ananthan Adams, Elizabeth A.K. Zaritsky, Dennis Battaglia, Giuseppina Seth, Anil Cannon, John M. Fuson, Jackson Inoue, John L. Mutlu-Pakdil, Burçin Guhathakurta, Puragra Muñoz, Ricardo R. Bennet, Paul Crnojević, Denija Caldwell, Nelson Strader, Jay Toloba, Elisa INAF Osservatorio di Astrofisica e Scienza Dello Spazio di Bologna Via Gobetti 93/3 Bologna40129 Italy INAF-Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze50125 Italy Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States European Southern Observatory Karl-Schwarzschild-Straße 2 Garching bei MünchenD-85748 Germany Department of Physics and Space Science Royal Military College of Canada P.O. Box 17000 Station Forces Kingston ONK7K 7B4 Canada Department of Physics Engineering Physics and Astronomy Queens University KingstonONK7L 3N6 Canada Glorieta de la Astronomía Granada18008 Spain Department of Physics Engineering Physics and Astronomy Queens University KingstonONK7L 3N6 Canada ASTRON Netherlands Institute for Radio Astronomy Oude Hoogeveensedijk 4 Dwingeloo7991 PD Netherlands Kapteyn Astronomical Institute University of Groningen PO Box 800 Groningen9700 AV Netherlands Instituto de Astrofísica de Canarias Vía Láctea s/n La Laguna38205 Spain Department of Astrophysics University of la Laguna San Cristóbal de La LagunaE-38206 Spain Department of Physics & Astronomy University of Utah Salt Lake CityUT84112 United States Department of Physics & Astronomy Macalester College 1600 Grand Avenue Saint PaulMN55105 United States Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL60637 United States UCO/Lick Observatory University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Departamento de Astronomía Universidad de Chile Camino El Observatorio 1515 Las Condes Santiago Chile Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States University of Tampa 401 West Kennedy Boulevard TampaFL33606 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United State

We use panoramic optical spectroscopy obtained with MUSE@VLT to investigate the nature of five candidate extremely isolated low-mass star forming regions (Blue Candidates, BCs hereafter) toward the Virgo cluster of galaxies. Four of the five (BC1, BC3, BC4, BC5) are found to host several Hii regions and to have radial velocities fully compatible with being part of the Virgo cluster. All the confirmed candidates have mean metallicity significantly in excess of that expected from their stellar mass, indicating that they originated from gas stripped from larger galaxies. In summary, these four candidates share the properties of the prototype system SECCO 1, suggesting the possible emergence of a new class of stellar systems, intimately linked to the complex duty cycle of gas within clusters of galaxies. A thorough discussion on the nature and evolution of these objects is presented in a companion paper, where the results obtained here from MUSE data are complemented with Hubble Space Telescope (optical) and Very Large Array (Hi) observations. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies

QTT-isogeometric solver in two dimensions

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arXiv 2018年

作者： Markeeva, L. Tsybulin, I. Oseledets, I. Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia Department of Applied Math and Control Moscow Institute of Physics and Technology Moscow Russia Laboratory of Fluid Dynamics and Seismics Moscow Institute of Physics and Technology Moscow Russia Institute of Numerical Mathematics Russian Academy of Sciences Moscow Russia

Young, blue, and isolated stellar systems in the Virgo Cluster. II. A new class of stellar system

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arXiv 2022年

作者： Jones, Michael G. Sand, David J. Bellazzini, Michele Spekkens, Kristine Karunakaran, Ananthan Adams, Elizabeth A.K. Battaglia, Giuseppina Beccari, Giacomo Bennet, Paul Cannon, John M. Cresci, Giovanni Crnojević, Denija Caldwell, Nelson Fuson, Jackson Guhathakurta, Puragra Haynes, Martha P. Inoue, John L. Magrini, Laura Muñoz, Ricardo R. Mutlu-Pakdil, Burçin Seth, Anil Strader, Jay Toloba, Elisa Zaritsky, Dennis Steward Observatory University of Arizona 933 North Cherry Avenue Rm. N204 TucsonAZ85721-0065 United States INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Gobetti 93/3 Bologna40129 Italy Department of Physics and Space Science Royal Military College of Canada P.O. Box 17000 Station Forces Kingston ONK7K 7B4 Canada Department of Physics Engineering Physics and Astronomy Queen's University KingstonONK7L 3N6 Canada Glorieta de la Astronomía Granada18008 Spain ASTRON The Netherlands Institute for Radio Astronomy Oude Hoogeveesedijk 4 Dwingeloo 7991 PD Netherlands Kapteyn Astronomical Institute PO Box 800 Groningen9700 AV Netherlands Instituto de Astrofísica de Canarias Vía Láctea s/n La Laguna 38205 Spain Universidad de La Laguna Avda. Astrofísico Fco. Sánchez Tenerife La LagunaE-38205 Spain European Southern Observatory Karl-Schwarzschild-Strasse 2 Garching bei München D-85748 Germany Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Physics & Astronomy Macalester College 1600 Grand Avenue Saint PaulMN55105 United States INAF - Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze50125 Italy University of Tampa 401 West Kennedy Boulevard TampaFL33606 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States UCO/Lick Observatory University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Cornell Center for Astrophysics and Planetary Science Space Sciences Building Cornell University IthacaNY14853 United States Departamento de Astronomía Universidad de Chile Camino El Observatorio 1515 Las Condes Santiago Chile Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL60637 United States Department of Physics & Astronomy University of Utah Salt Lake City

We discuss five blue stellar systems in the direction of the Virgo cluster, analogous to the enigmatic object SECCO 1 (AGC 226067). These objects were identified based on their optical and UV morpholog☉y and followed up with H i observations with the VLA (and GBT), MUSE/VLT optical spectroscopy, and HST imaging. These new data indicate that one system is a distant group of galaxies. The remaining four are extremely low mass (M∗ ∼ 105 M☉), are dominated by young, blue stars, have highly irregular and clumpy morphologies, are only a few kpc across, yet host an abundance of metal-rich, 12 + log(O/H) > 8.2, H ii regions. These high metallicities indicate that these stellar systems formed from gas stripped from much more massive galaxies. Despite the young age of their stellar populations, only one system is detected in H i, while the remaining three have minimal (if any) gas reservoirs. Furthermore, two systems are surprisingly isolated and have no plausible parent galaxy within ∼30' (∼140 kpc). Although tidal stripping cannot be conclusively excluded as the formation mechanism of these objects, ram pressure stripping more naturally explains their properties, in particular their isolation, owing to the higher velocities, relative to the parent system, that can be achieved. Therefore, we posit that most of these systems formed from ram pressure stripped gas removed from new infalling cluster members, and survived in the intracluster medium long enough to become separated from their parent galaxies by hundreds of kiloparsecs, and that they thus represent a new type of stellar system. © 2022, CC BY.

关键词： Galaxies

Numerical studies of solutions for kinetic equations with many-particle collisions

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Journal of Physics: Conference Series 2019年第1期1163卷 012008-012008页

作者： Matveev, S A Stefonishin, D A Smirnov, A P Sorokin, A A Tyrtyshnikov, E E Skoltech Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute for Science and Technology Moscow 121205 Russia Skoltech Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute for Science and Technology Moscow 121205 Russia Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State University Moscow 119992 Russia Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State University Moscow 119992 Russia Nuclear Safety Institute Russian Academy of Sciences Moscow 115191 Russia Marchuk Institute of Numerical Mathematics Russian Academy of Sciences Moscow 119333 Russia

In this work we present a method of low-rank tensor decompositions to accelerate evaluation of the right-hand side of systems of kinetic equations with many-particle collisional terms. These equations can be interpreted as a generalization of classical Smoluchowski aggregation equations allowing one to consider not only binary collisions of particles but also triple collisions. Straight-forward evaluation of the right-hand side for such system of N equations with k = 1, 2,…, N requires O(N 3) numerical operations and we find such complexity too high for practical investigations. However, under assumptions that kinetic coefficients can be represented with either canonical polyadic (CP) or tensor train decomposition (TT) with the rank R ≪ N we can propose algorithms evaluating the right-hand side with much lower complexities: O(NRlog N) and O(NR 2 log N) for CP and TT respectively. We compare numerical solutions with different triple-collision rates and obtain a significant influence of accounting triple collisional effects.

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Hubble space telescope imaging of isolated local volume dwarfs GALFA-Dw3 and Dw4

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arXiv 2021年

作者： Bennet, Paul Sand, D.J. Crnojević, D. Weisz, D.R. Caldwell, N. Guhathakurta, P. Hargis, J.R. Karunakaran, A. Mutlu-Pakdil, B. Olszewski, E. Salzer, J.J. Seth, A.C. Simon, J.D. Spekkens, K. Stark, D.P. Strader, J. Tollerud, E.J. Toloba, E. Willman, B. Physics & Astronomy Department Texas Tech University Box 41051 LubbockTX79409-1051 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Astronomy/Steward Observatory The University of Arizona 933 North Cherry Avenue Rm. N204 TucsonAZ85721-0065 United States University of Tampa Department of Chemistry Biochemistry and Physics 401 West Kennedy Boulevard TampaFL33606 United States University of California Berkeley Department of Astronomy 501 Campbell Hall # 3411 BerkeleyCA94720-3411 United States Harvard-Smithsonian Center for Astrophysics 60 Garden Street CambridgeMA02138 United States UCO/Lick Observatory University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Space Telescope Science Institute 3800 San Martin Drive BaltimoreMD21208 United States Department of Physics Engineering Physics and Astronomy Queen’s University KingstonONK7L 3N6 Canada Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL60637 United States Department of Astronomy Indiana University 727 East Third Street BloomingtonIN47405 United States Department of Physics and Astronomy University of Utah 115 South 1400 East Salt Lake CityUT84112 United States Observatories of the Carnegie Institution for Science PasadenaCA91101 United States Department of Physics and Space Science Royal Military College of Canada P.O. Box 17000 Station Forces KingstonONK7K 7B4 Canada Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Physics University of the Pacific 3601 Pacific Avenue StocktonCA95211 United States LSST and Steward Observatory 933 North Cherry Avenue TucsonAZ85721 United States

We present observations of the dwarf galaxies GALFA Dw3 and GALFA Dw4 with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). These galaxies were initially discovered as optical counterparts to compact HI clouds in the GALFA survey. Both objects resolve into stellar populations which display an old red giant branch, younger helium burning, and massive main sequence stars. We use the tip of the red giant branch method to determine the distance to each galaxy, finding distances of 7.61+0−0..2829 Mpc and 3.10+0−0..1617 Mpc, respectively. With these distances we show that both galaxies are extremely isolated, with no other confirmed objects within ∼1.5 Mpc of either dwarf. GALFA Dw4 is also found to be unusually compact for a galaxy of its luminosity. GALFA Dw3 & Dw4 contain HII regions with young star clusters and an overall irregular morphology;they show evidence of ongoing star formation through both ultraviolet and Hα observations and are therefore classified as dwarf irregulars (dIrrs). The star formation histories of these two dwarfs show distinct differences: Dw3 shows signs of a recently ceased episode of active star formation across the entire dwarf, while Dw4 shows some evidence for current star formation in spatially limited HII regions. Compact HI sources offer a promising method for identifying isolated field dwarfs in the Local Volume, including GALFA Dw3 & Dw4, with the potential to shed light on the driving mechanisms of dwarf galaxy formation and evolution. © 2021, CC BY.

关键词： Galaxies

SN 2022acko: the First Early Far-Ultraviolet Spectra of a Type IIP Supernova

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arXiv 2023年

作者： Bostroem, K. Azalee Dessart, Luc Hillier, D. John Lundquist, Michael Andrews, Jennifer E. Sand, David J. Dong, Yize Valenti, Stefano Haislip, Joshua Hoang, Emily T. Hosseinzadeh, Griffin Janzen, Daryl Jencson, Jacob E. Jha, Saurabh W. Kouprianov, Vladimir Pearson, Jeniveve Meza Retamal, Nicolas E. Reichart, Daniel E. Shrestha, Manisha Ashall, Christopher Baron, E. Brown, Peter J. DerKacy, James M. Farah, Joseph Galbany, Lluís Hernández, J.I. González Green, Elizabeth Hoeflich, Peter Howell, D. Andrew Kwok, Lindsey A. McCully, Curtis Müller-Bravo, Tomás E. Newsome, Megan Gonzalez, Estefania Padilla Pellegrino, Craig Rho, Jeonghee Rowe, Micalyn Schwab, Michaela Shahbandeh, Melissa Smith, Nathan Strader, Jay Terreran, Giacomo Van Dyk, Schuyler D. Wyatt, Samuel Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States Institut d’Astrophysique de Paris CNRS-Sorbonne Université 98 bis boulevard Arago Paris75014 France University of Pittsburgh 3941 O’Hara Street PittsburghPA15260 United States W. M. Keck Observatory 65-1120 Māmalahoa Highway KamuelaHI96743-8431 United States Gemini Observatory 670 North A‘ohoku Place HiloHI96720-2700 United States Department of Physics and Astronomy University of California Davis 1 Shields Avenue DavisCA95616-5270 United States Department of Physics and Astronomy University of North Carolina 120 East Cameron Avenue Chapel HillNC27599 United States Department of Physics and Engineering Physics University of Saskatchewan 116 Science Place SaskatoonSKS7N 5E2 Canada Department of Physics and Astronomy The Johns Hopkins University 3400 North Charles Street BaltimoreMD21218 United States Department of Physics and Astronomy Rutgers the State University of New Jersey 136 Frelinghuysen Road PiscatawayNJ08854-8019 United States Department of Physics Virginia Tech BlacksburgVA24061 United States Planetary Science Institute 1700 East Fort Lowell Suite 106 TucsonAZ85719-2395 United States Hamburger Sternwarte Gojenbergsweg 112 HamburgD-21029 Germany Homer L. Dodge Department of Physics and Astronomy University of Oklahoma 440 W. Brooks Rm 100 NormanOK73019-2061 United States Department of Physics and Astronomy Texas A&M University 4242 TAMU College StationTX77843 United States Las Cumbres Observatory 6740 Cortona Drive Suite 102 GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain Institut d’Estudis Espacials de Catalunya Gran Capità 2-4 Edifici Nexus Desp. 201 BarcelonaE-08034 Spain Instituto de Astrofísica de Canarias La Laguna TenerifeE-38205 Spain Universidad de La Lag

We present five far- and near-ultraviolet spectra of the Type II plateau supernova, SN 2022acko, obtained 5, 6, 7, 19, and 21 days after explosion, all observed with the Hubble Space Telescope/Space Telescope Imaging Spectrograph. The first three epochs are earlier than any Type II plateau supernova has been observed in the far-ultraviolet revealing unprecedented characteristics. These three spectra are dominated by strong lines, primarily from metals, which contrasts with the featureless early optical spectra. The flux decreases over the initial time series as the ejecta cool and line-blanketing takes effect. We model this unique dataset with the non-local thermodynamic equilibrium radiation transport code CMFGEN, finding a good match to the explosion of a low-mass red supergiant with energy Ekin = 6 × 1050 erg. With these models we identify, for the first time, the ions that dominate the early ultraviolet spectra. We present optical photometry and spectroscopy, showing that SN 2022acko has a peak absolute magnitude of V = −15.4 mag and plateau length of ∼ 115d. The spectra closely resemble those of SN 2005cs and SN 2012A. Using the combined optical and ultraviolet spectra, we report the fraction of flux as a function of bluest wavelength on days 5, 7, and 19. We create a spectral time-series of Type II supernovae in the ultraviolet, demonstrating the rapid decline of flux over the first few weeks of evolution. Future observations of Type II supernovae are required to map out the landscape of exploding red supergiants, with and without circumstellar material, which is best revealed in high-quality ultraviolet spectra. © 2023, CC BY.

关键词： Supernovae