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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 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 Briceño, César 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 Fűrész, Gábor and Huang, Chelsea 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. Astronomical Journal, 161 (2). Art. No. 97. ISSN 1538-3881. doi:10.3847/1538-3881/abd4e1.

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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 M_b = 59.9 ± 13.0M J and radius of R_b = 1.26 ± 0.06R J, 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 M_b = 53.7 ± 1.4M J 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 R_b = 0.83 ± 0.04R_J. 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⋆ = 1.32 M_⊙ ± 0.05 and differ in their radii, T_(eff_, and [Fe/H], with TOI-811 having R⋆ = 1.27 ± 0.09 R_⊙, T_(eff) = 6107 ± 77 K, and [Fe/H] = + 0.40 ± 0.09 and TOI-852 having R⋆ = 1.71 ± 0.04 R_⊙, T_(eff) = 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Carmichael, Theron W.0000-0001-6416-1274
Quinn, Samuel N.0000-0002-8964-8377
Zhou, George0000-0002-4891-3517
Grieves, Nolan0000-0001-8105-0373
Stassun, Keivan G.0000-0002-3481-9052
Vanderburg, Andrew M.0000-0001-7246-5438
Winn, Joshua N.0000-0002-4265-047X
Bouchy, Francois0000-0002-7613-393X
Brasseur, Clara E.0000-0002-9314-960X
Briceño, César0000-0001-7124-4094
Caldwell, Douglas A.0000-0003-1963-9616
Charbonneau, David0000-0002-9003-484X
Collins, Karen A.0000-0001-6588-9574
Colon, Knicole D.0000-0001-8020-7121
Eastman, Jason D.0000-0003-3773-5142
Fausnaugh, Michael0000-0002-9113-7162
Fong, William0000-0001-7416-7522
Huang, Chelsea0000-0003-0918-7484
Jenkins, Jon M.0000-0002-4715-9460
Kielkopf, John F.0000-0003-0497-2651
Latham, David W.0000-0001-9911-7388
Law, Nicholas0000-0001-9380-6457
Lund, Michael B.0000-0003-2527-1598
Mann, Andrew W.0000-0003-3654-1602
Ricker, George R.0000-0003-2058-6662
Rodriguez, Joseph E.0000-0001-8812-0565
Schwarz, Richard P.0000-0001-8227-1020
Shporer, Avi0000-0002-1836-3120
Tenenbaum, Peter0000-0002-1949-4720
Wood, Mackenna L.0000-0001-7336-7725
Ziegler, Carl0000-0002-0619-7639
Additional Information:© 2021 The American Astronomical Society. Received 2020 September 28; revised 2020 December 4; accepted 2020 December 16; published 2021 January 29. Funding for the TESS mission is provided by NASA's Science Mission directorate. This paper includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Funding for this work is provided by the National Science Foundation Graduate Research Fellowship Program Fellowship (GRFP). T.W.C. acknowledges the efforts of the members of the TESS Follow-up Program and the Science Processing Operations Center in making the TESS data readily accessible for the analysis in this work. T.W.C. also thanks Adam Kraus and Elisabeth Newton for contributing discussions. The MEarth Team gratefully acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering (awarded to D.C.). This material is based on work supported by the National Science Foundation under grants AST-0807690, AST-1109468, AST-1004488 (Alan T. Waterman Award), and AST-1616624 and on work supported by the National Aeronautics and Space Administration under grant No. 80NSSC18K0476 issued through the XRP Program. This work is made possible by a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. This work makes use of observations from the LCOGT network. The authors thank the reviewer for the timely feedback and thoughtful comments. Facilities: TESS - , Las Cumbres Observatory Global Telescope (LCOGT) - , SuperWASP - , SOAR (HRCam) - , Gaia - , FLWO:1.5 m (TRES) - , CTIO:1.5 m (CHIRON) - , Euler:1.2 m (CORALIE) - , WISE (infrared) - , CTIO:2MASS (optical - , infrared) - , MEarth (Optical). - Software: EXOFASTv2 (Eastman et al. 2019), SPC (Buchhave et al. 2012), LCO BANZAI (Collins et al. 2017), AstroImageJ (Collins et al. 2017).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
John Templeton FoundationUNSPECIFIED
Subject Keywords:Brown dwarfs ; Radial velocity ; Transit photometry ; Spectroscopy ; Photometry ; Substellar companion stars
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Brown dwarfs (185); Radial velocity (1332); Transit photometry (1709); Spectroscopy (1558); Photometry (1234); Substellar companion stars (1648)
Record Number:CaltechAUTHORS:20210201-121442659
Persistent URL:
Official Citation:Theron W. Carmichael et al 2021 AJ 161 97
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107834
Deposited By: Tony Diaz
Deposited On:01 Feb 2021 21:47
Last Modified:16 Nov 2021 19:06

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