TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

Subjak, Jan and Sharma, Rishikesh and Carmichael, Theron W. and Johnson, Marshall C. and Gonzales, Erica J. and Matthews, Elisabeth and Boffin, Henri M. J. and Brahm, Rafael and Chaturvedi, Priyanka and Chakraborty, Abhijit and Ciardi, David R. and Collins, Karen A. and Esposito, Massimiliano and Fridlund, Malcolm and Gan, Tianjun and Gandolfi, Davide and Garcia, Rafael A. and Guenther, Eike and Hatzes, Artie and Latham, David W. and Mathis, Stephane and Mathur, Savita and Persson, Carina M. and Relles, Howard M. and Schlieder, Joshua E. and Barclay, Thomas and Dressing, Courtney D. and Crossfield, Ian and Howard, Andrew W. and Rodler, Florian and Zhou, George ORCID: and Quinn, Samuel N. and Esquerdo, Gilbert A. and Calkins, Michael L. and Berlind, Perry and Stassun, Keivan G. and Blazek, Martin and Skarka, Marek and Spokova, Magdalena and Zak, Jiri and Albrecht, Simon and Sobrino, Roi and Beck, Paul and Cabrera, Juan and Carleo, Ilaria and Cochran, William D. and Csizmadia, Szilard and Dai, Fei and Deeg, Hans J. and de Leon, Jerome P. and Eigmuller, Philipp and Endl, Michael and Erikson, Anders and Fukui, Akihiko and Georgieva, Iskra and Gonzalez-Cuesta, Lucia and Grziwa, Sascha and Hidalgo, Diego and Hirano, Teruyuki and Hjorth, Maria and Knudstrup, Emil and Korth, Judith and Lam, Kristine W. F. and Livingston, John H. and Lund, Mikkel N. and Luque, Rafael and Montanes Rodriguez, Pilar and Murgas, Felipe and Narita, Norio and Nespral, David and Niraula, Prajwal and Nowak, Grzegorz and Palle, Enric and Patzold, Martin and Prieto-Arranz, Jorge and Rauer, Heike and Redfield, Seth and Ribas, Ignasi and Smith, Alexis M. S. and Van Eylen, Vincent and Kabath, Petr (2020) TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission. The Astronomical Journal, 159 (4):151. pp. 1-19. ISSN 0004-6256

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We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P = 3.6772 ± 0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius . We obtained high-resolution spectroscopic observations with the FIES, Ondrejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be M b = 53.7 ± 1.2 a radius of R = 1.70 ± 0.05R o, an effective temperature of T eff = 7650 ± 160 K, and a relatively high metallicity of 0.61 ± 0.07 dex. We used stellar isochrones to derive the age of the system to be ∼180 Myr, which places its age between that of RIK 72b (a ∼10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a ∼600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting main-sequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert is reforesting.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 10 Feb 2022 03:17
Last Modified: 14 Feb 2022 02:20
Uncontrolled Keywords: Brown dwarfs; Stellar ages; Am stars; Spectroscopy; Transit photometry; Radial velocity; Stellar rotation; Stellar astronomy; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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