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Three low-mass companions around aged stars discovered by TESS

Lin, Zitao; Gan, Tianjun; Wang, Sharon X; Shporer, Avi; Rabus, Markus; Zhou, George; Psaridi, Angelica; Bouchy, François; Bieryla, Allyson; Latham, David W; Mao, Shude; Stassun, Keivan G; Hellier, Coel; Howell, Steve B; Ziegler, Carl; Caldwell, Douglas A; Clark, Catherine A; Collins, Karen A; Curtis, Jason L; Faherty, Jacqueline K; Gnilka, Crystal L; Grunblatt, Samuel K; Jenkins, Jon M; Johnson, Marshall C; Law, Nicholas; Lendl, Monika; Littlefield, Colin; Lund, Michael B; Lund, Mikkel N; Mann, Andrew W; McDermott, Scott; Mishra, Lokesh; Mounzer, Dany; Paegert, Martin; Pritchard, Tyler; Ricker, George R; Seager, Sara; Srdoc, Gregor; Sun, Qinghui; Tang, Jiaxin; Udry, Stéphane; Vanderspek, Roland; Watanabe, David; Winn, Joshua N; Yu, Jie

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Zitao Lin

Tianjun Gan

Sharon X Wang

Avi Shporer

Markus Rabus

George Zhou

Angelica Psaridi

François Bouchy

Allyson Bieryla

David W Latham

Shude Mao

Keivan G Stassun

Steve B Howell

Carl Ziegler

Douglas A Caldwell

Catherine A Clark

Karen A Collins

Jason L Curtis

Jacqueline K Faherty

Crystal L Gnilka

Samuel K Grunblatt

Jon M Jenkins

Marshall C Johnson

Nicholas Law

Monika Lendl

Colin Littlefield

Michael B Lund

Mikkel N Lund

Andrew W Mann

Scott McDermott

Lokesh Mishra

Dany Mounzer

Martin Paegert

Tyler Pritchard

George R Ricker

Sara Seager

Gregor Srdoc

Qinghui Sun

Jiaxin Tang

Stéphane Udry

Roland Vanderspek

David Watanabe

Joshua N Winn

Jie Yu


We report the discovery of three transiting low-mass companions to aged stars: a brown dwarf (TOI-2336b) and two objects near the hydrogen burning mass limit (TOI-1608b and TOI-2521b). These three systems were first identified using data from the Transiting Exoplanet Survey Satellite (TESS). TOI-2336b has a radius of 1.05 ± 0.04 RJ, a mass of 69.9 ± 2.3 MJ and an orbital period of 7.71 days. TOI-1608b has a radius of 1.21 ± 0.06 RJ, a mass of 90.7 ± 3.7 MJ and an orbital period of 2.47 days. TOI-2521b has a radius of 1.01 ± 0.04 RJ, a mass of 77.5 ± 3.3 MJ and an orbital period of 5.56 days. We found all these low-mass companions are inflated. We fitted a relation between radius, mass and incident flux using the sample of known transiting brown dwarfs and low-mass M dwarfs. We found a positive correlation between the flux and the radius for brown dwarfs and for low-mass stars that is weaker than the correlation observed for giant planets. We also found that TOI-1608 and TOI-2521 are very likely to be spin-orbit synchronized, leading to the unusually rapid rotation of the primary stars considering their evolutionary stages. Our estimates indicate that both systems have much shorter spin-orbit synchronization timescales compared to their ages. These systems provide valuable insights into the evolution of stellar systems with brown dwarf and low-mass stellar companions influenced by tidal effects.

Journal Article Type Article
Acceptance Date Jun 5, 2023
Online Publication Date Jun 15, 2023
Publication Date 2023-08
Deposit Date Jul 4, 2023
Publicly Available Date Aug 22, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 523
Issue 4
Pages 6162–6185
Keywords Space and Planetary Science, Astronomy and Astrophysics


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© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (

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