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arXiv · 2210.13939

Three low-mass companions around aged stars discovered by TESS

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·Coel Hellier·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
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Abstract

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 $1.05\pm 0.04\ R_J$, a mass of $69.9\pm 2.3\ M_J$ and an orbital period of 7.71 days. TOI-1608b has a radius of $1.21\pm 0.06\ R_J$, a mass of $90.7\pm 3.7\ M_J$ and an orbital period of 2.47 days. TOI-2521b has a radius of $1.01\pm 0.04\ R_J$, a mass of $77.5\pm 3.3\ M_J$ 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.

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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, Coel Hellier, 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. 2022-10-25. Three low-mass companions around aged stars discovered by TESS. https://doi.org/10.1093/mnras%2Fstad1745

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