TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission

Carmichael, Theron W. and Quinn, Samuel N. and Zhou, George ORCID: https://orcid.org/0000-0002-4891-3517 and Grieves, Nolan and Irwin, Jonathan M. and Stassun, Keivan G. and Vanderburg, Andrew M. and Winn, Joshua N. and Bouchy, Francois and Brasseur, Clara E. and Briceno, Cesar and Caldwell, Douglas A. and Charbonneau, David and Collins, Karen A. and Colon, Knicole D. and Eastman, Jason D. and Fausnaugh, Michael and Fong, William and Furesz, Gabor and Huang, Chelsea ORCID: https://orcid.org/0000-0003-0918-7484 and Jenkins, Jon M. and Kielkopf, John F. and Latham, David W. and Law, Nicholas and Lund, Michael B. and Mann, Andrew W. and Ricker, George R. and Rodriguez, Joseph E. and Schwarz, Richard P. and Shporer, Avi and Tenenbaum, Peter and Wood, Mackenna L. and Ziegler, Carl (2021) TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission. The Astronomical Journal, 161 (2):97. pp. 1-17. ISSN 0004-6256


Abstract

We report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASA's Transiting Exoplanet Survey Satellite mission. These two transiting BDs have similar masses but very different radii and ages. Their host stars have similar masses, effective temperatures, and metallicities. The younger and larger transiting BD is TOI-811b at a mass of Mb = 59.9 ± 13.0MJ and radius of Rb = 1.26 ± 0.06RJ, and it orbits its host star in a period of P = 25.16551 ± 0.00004 days. We derive the host star's age of 93+61-29 Myr from an application of gyrochronology. The youth of this system, rather than external heating from its host star, is why this BD's radius is relatively large. This constraint on the youth of TOI-811b allows us to test substellar mass-radius evolutionary models at young ages where the radius of BDs changes rapidly. TOI-852b has a similar mass at Mb = 53.7 ± 1.4MJ but is much older (4 or 8 Gyr, based on bimodal isochrone results of the host star) and is also smaller with a radius of Rb = 0.83 ± 0.04RJ. TOI-852b's orbital period is P = 4.94561 ± 0.00008 days. TOI-852b joins the likes of other old transiting BDs that trace out the oldest substellar mass-radius evolutionary models where contraction of the BD's radius slows and approaches a constant value. Both host stars have a mass of M∗ = 1.32M⊙ ± 0.05 and differ in their radii, Teff, and [Fe/H], with TOI-811 having R∗ = 1.27 ± 0.09R⊙, Teff = 6107 ± 77 K, and [Fe/ H]=+0.40 ± 0.09 and TOI-852 having R∗ = 1.71 ± 0.04R⊙, Teff = 5768 ± 84 K, and [Fe/H]=+0.33 ± 0.09. We take this opportunity to examine how TOI-811b and TOI-852b serve as test points for young and old substellar isochrones, respectively.


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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: 07 Mar 2022 04:26
Last Modified: 30 Mar 2022 03:49
Uncontrolled Keywords: Brown dwarfs; Radial velocity; Transit photometry; Spectroscopy; Photometry; Substellar companion stars; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-3881/abd4e1
URI: http://eprints.usq.edu.au/id/eprint/44976

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