LHS 1815b: The First Thick-disk Planet Detected by TESS

Gan, Tianjun; Shporer, Avi; Livingston, John H.; Collins, Karen A.; Mao, Shude; Trani, Alessandro A.; Gandolfi, Davide; Hirano, Teruyuki; Luque, Rafael; Stassun, Keivan G.; Ziegler, Carl; Howell, Steve B.; Hellier, Coel; Irwin, Jonathan M.; Winters, Jennifer G.; Anderson, David R.; Briceño, César; Law, Nicholas; Mann, Andrew W.; Bonfils, Xavier; Astudillo-Defru, Nicola; Jensen, Eric L. N.; Anglada-Escudé, Guillem; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Furesz, Gabor; Guerrero, Natalia M.; Quintana, Elisa; Twicken, Joseph D.; Caldwell, Douglas A.; Tenenbaum, Peter; Huang, Chelsea X.; Rowden, Pamela; Rojas-Ayala, Bárbara

Abstract

We report the first discovery of a thick-disk planet, LHS 1815b (TOI-704b, TIC 260004324), detected in the Transiting Exoplanet Survey Satellite (TESS) survey. LHS 1815b transits a bright (V = 12.19 mag, K = 7.99 mag) and quiet M dwarf located 29.87 ± 0.02 pc away with a mass of 0.502 ± 0.015 M⊙ and a radius of 0.501 ± 0.030 R⊙. We validate the planet by combining space- and ground-based photometry, spectroscopy, and imaging. The planet has a radius of 1.088 ± 0.064 R⊕ with a 3σ mass upper limit of 8.7 M⊕. We analyze the galactic kinematics and orbit of the host star LHS 1815 and find that it has a large probability (Pthick/Pthin = 6482) to be in the thick disk with a much higher expected maximal height (Zmax = 1.8 kpc) above the Galactic plane compared with other TESS planet host stars. Future studies of the interior structure and atmospheric properties of planets in such systems using, for example, the upcoming James Webb Space Telescope, can investigate the differences in formation efficiency and evolution for planetary systems between different Galactic components (thick disks, thin disks, and halo).

Citation

Gan, T., Shporer, A., Livingston, J. H., Collins, K. A., Mao, S., Trani, A. A., …Rojas-Ayala, B. (in press). LHS 1815b: The First Thick-disk Planet Detected by TESS. Astronomical Journal, 159(4), 160. https://doi.org/10.3847/1538-3881/ab775a

• Journal Article Type: Article
• Acceptance Date: Feb 16, 2020
• Online Publication Date: Mar 18, 2020
• Deposit Date: Jun 16, 2023
• Journal: The Astronomical Journal
• Print ISSN: 0004-6256
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 159
• Issue: 4
• Pages: 160
• DOI: https://doi.org/10.3847/1538-3881/ab775a
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Additional Information: Journal title: The Astronomical Journal; Article type: paper; Article title: LHS 1815b: The First Thick-disk Planet Detected by TESS; Copyright information: © 2020. The American Astronomical Society. All rights reserved.; Date received: 2019-12-22; Date accepted: 2020-02-16; Online publication date: 2020-03-18