학술논문
The TESS-Keck Survey. II. An Ultra-short-period Rocky Planet and Its Siblings Transiting the Galactic Thick-disk Star TOI-561
Document Type
article
Author
Weiss, Lauren M; Dai, Fei; Huber, Daniel; Brewer, John M; Collins, Karen A; Ciardi, David R; Matthews, Elisabeth C; Ziegler, Carl; Howell, Steve B; Batalha, Natalie M; Crossfield, Ian JM; Dressing, Courtney; Fulton, Benjamin; Howard, Andrew W; Isaacson, Howard; Kane, Stephen R; Petigura, Erik A; Robertson, Paul; Roy, Arpita; Rubenzahl, Ryan A; Twicken, Joseph D; Claytor, Zachary R; Stassun, Keivan G; MacDougall, Mason G; Chontos, Ashley; Giacalone, Steven; Dalba, Paul A; Mocnik, Teo; Hill, Michelle L; Beard, Corey; Murphy, Joseph M Akana; Rosenthal, Lee J; Behmard, Aida; Van Zandt, Judah; Lubin, Jack; Kosiarek, Molly R; Lund, Michael B; Christiansen, Jessie L; Matson, Rachel A; Beichman, Charles A; Schlieder, Joshua E; Gonzales, Erica J; Briceño, César; Law, Nicholas; Mann, Andrew W; Collins, Kevin I; Evans, Phil; Fukui, Akihiko; Jensen, Eric LN; Murgas, Felipe; Narita, Norio; Palle, Enric; Parviainen, Hannu; Schwarz, Richard P; Tan, Thiam-Guan; Acton, Jack S; Bryant, Edward M; Chaushev, Alexander; Gill, Sam; Eigmüller, Philipp; Jenkins, Jon; Ricker, George; Seager, Sara; Winn, Joshua N
Source
The Astronomical Journal. 161(2)
Subject
Language
Abstract
We report the discovery of TOI-561, a multiplanet system in the galactic thick disk that contains a rocky, ultrashort- period planet. This bright (V = 10.2) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561 b (TOI-561.02, P = 0.44 days, Rp = 1.45 ± 0.11 R⊕), c (TOI-561.01, P = 10.8 days, Rp = 2.90 ± 0.13 R⊕), and d (TOI-561.03, P = 16.3 days, Rp = 2.32 ± 0.16 R⊕). The star is chemically ([Fe/ H] = -0.41 ± 0.05, [a/Fe]=+0.23 ± 0.05) and kinematically consistent with the galactic thick-disk population, making TOI-561 one of the oldest (10 ± 3 Gyr) and most metal-poor planetary systems discovered yet. We dynamically confirm planets b and c with radial velocities from the W. M. Keck Observatory High Resolution Echelle Spectrometer. Planet b has a mass and density of 3.2 ± 0.8M⊕ and 5.5+2.0-1.6g cm-3, consistent with a rocky composition. Its lower-than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out. Planet c is 7.0 ± 2.3M⊕ and 1.6 ± 0.6 g cm-3, consistent with an interior rocky core overlaid with a low-mass volatile envelope. Several attributes of the photometry for planet d (which we did not detect dynamically) complicate the analysis, but we vet the planet with high-contrast imaging, groundbased photometric follow-up, and radial velocities. TOI-561 b is the first rocky world around a galactic thick-disk star confirmed with radial velocities and one of the best rocky planets for thermal emission studies.