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TOI-503: The first known brown dwarf-Am star binary from the TESS mission

Šubjak, Ján and Ciardi, David R. and Howard, Andrew W. (2020) TOI-503: The first known brown dwarf-Am star binary from the TESS mission. Astronomical Journal, 159 (4). Art. No. 151. ISSN 1538-3881.

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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 (R_b = 1.34^(+0.26)_(−0.15)R_J). We obtained high-resolution spectroscopic observations with the FIES, Ondřejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be M_b = 53.7 ± 1.2 M_J. The host star has a mass of M⋆ = 1.80 ± 0.06 M⊙, a radius of R⋆ = 1.70 ± 0.05R⊙, 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 (35−55M_J sin i) is reforesting.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ciardi, David R.0000-0002-5741-3047
Howard, Andrew W.0000-0001-8638-0320
Additional Information:© 2020 The American Astronomical Society. Received 2019 September 16; revised 2019 December 23; accepted 2020 January 31; published 2020 March 27. This work is done under the framework of the KESPRINT collaboration ( KESPRINT is an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions. J.Š. and P.K. would like to acknowledge the support from GACR international grant 17-01752J. J.Š. would like to acknowledge the support from source 116-09/260441, Institute of Theoretical Physics, Charles University in Prague, Czech Republic. J.K., S.G., M.P., S.C., A.P.H., H.R., M.E., and K.W.F.L. acknowledge support by Deutsche Forschungsgemeinschaft (DFG) grants PA525/18-1, PA525/19-1, PA525/20-1, HA 3279/12-1, and RA 714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. S.C. acknowledges the Hungarian Scientific Research Fund (OTKA) Grant KH-130372. This work is partly supported by JSPS KAKENHI grant Nos. JP18H01265 and JP18H05439, and JST PRESTO grant No. JPMJPR1775. S.M. acknowledges support by the Spanish Ministry through the Ramon y Cajal fellowship number RYC-2015-17697. R.A.G. acknowledges the support from the PLATO/CNES grant. M.S. acknowledges the Postdoc@MUNI project CZ.02.2.69/0.0/0.0/16-027/0008360. S.M. acknowledges support from the ERC SPIRE 647383 grant. M.F., C.M.P., and I.G. gratefully acknowledge the support of the Swedish National Space Agency (DNR 163/16 and 174/18). K.G.S. acknowledges partial support from NASA grant 17-XRP17 2-0024. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias. Also based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program P103.C-0449. T.W.C. would like to acknowledge the effort of the observers who acquired the ground-based photometry at FLWO, LCO, CHAT, and FLI as part of the TESS Follow-up Program. Thanks to Alex J. Mustill and Scott Gaudi for useful discussions. The PARAS spectrograph is fully funded and being supported by Physical Research Laboratory (PRL), which is part of Department of Space, Government of India. R.S. and A.C. would like to thank Director P.R.L. for his support and acknowledges the help from Vishal Shah and the Mount Abu Observatory staff at the time of observations. A.C. is grateful to Suvrath Mahadevan from Pennsylvania State University and Arpita Roy from Caltech, for their tremendous efforts in the development of the PARAS data pipeline.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Grantová agentura České republiky (GAČR)17-01752J
Institute of Theoretical Physics116-09/260441
Charles UniversityUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)PA525/18-1
Deutsche Forschungsgemeinschaft (DFG)PA525/19-1
Deutsche Forschungsgemeinschaft (DFG)PA525/20-1
Deutsche Forschungsgemeinschaft (DFG)HA 3279/12-1
Deutsche Forschungsgemeinschaft (DFG)RA 714/14-1
Deutsche Forschungsgemeinschaft (DFG)SPP 1992
National Research, Development, and Innovation Office (Hungary)KH-130372
Japan Society for the Promotion of Science (JSPS)JP18H01265
Japan Society for the Promotion of Science (JSPS)JP18H05439
Japan Science and Technology AgencyJPMJPR1775
Ramón y Cajal ProgrammeRYC-2015-17697
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Operational Programme Research, Development and Education ProjectCZ.02.2.69/0.0/0.0/16-027/0008360
European Research Council (ERC)647383
Swedish National Space AgencyDNR 163/16
Swedish National Space AgencyDNR 174/18
NASA17-XRP17 2-0024
Subject Keywords:Brown dwarfs ; Stellar ages ; Am stars ; Spectroscopy ; Transit photometry ; Radial velocity ; Stellar rotation ; Stellar astronomy
Issue or Number:4
Classification Code:Unified Astronomy Thesaurus concepts: Brown dwarfs (185); Stellar ages (1581); Am stars (33); Spectroscopy (1558); Transit photometry (1709); Radial velocity (1332); Stellar rotation (1629); Stellar astronomy (1583)
Record Number:CaltechAUTHORS:20191120-111042566
Persistent URL:
Official Citation:Ján Šubjak et al 2020 AJ 159 151
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99956
Deposited By: Tony Diaz
Deposited On:20 Nov 2019 19:28
Last Modified:30 Mar 2020 17:15

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