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

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 ± 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.

Citation

Lin, Z., Gan, T., Wang, S. X., Shporer, A., Rabus, M., Zhou, G., …Yu, J. (2023). Three low-mass companions around aged stars discovered by TESS. Monthly Notices of the Royal Astronomical Society, 523(4), 6162–6185. https://doi.org/10.1093/mnras/stad1745

• 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
• DOI: https://doi.org/10.1093/mnras/stad1745
• Keywords: Space and Planetary Science, Astronomy and Astrophysics