The TESS-Keck Survey I: A Warm Sub-Saturn-mass Planet and a Caution about Stray Light in TESS Cameras
Creators: name: Dalba, Paul A.
name: Gupta, Arvind F.
name: Rodriguez, Joseph E.
name: Dragomir, Diana
name: Huang, Chelsea X.
name: Kane, Stephen R.
name: Quinn, Samuel N.
name: Bieryla, Allyson
name: Esquerdo, Gilbert A.
name: Fulton, Benjamin J.
name: Scarsdale, Nicholas
name: Batalha, Natalie M.
name: Beard, Corey
name: Behmard, Aida
name: Chontos, Ashley
name: Crossfield, Ian J. M.
name: Dressing, Courtney D.
name: Giacalone, Steven
name: Hill, Michelle L.
name: Hirsch, Lea A.
name: Howard, Andrew W.
name: Huber, Daniel
name: Isaacson, Howard
name: Kosiarek, Molly
name: Lubin, Jack
name: Mayo, Andrew W.
name: Mocnik, Teo
name: Murphy, Joseph M. Akana
name: Petigura, Erik A.
name: Robertson, Paul
name: Rosenthal, Lee J.
name: Roy, Arpita
name: Rubenzahl, Ryan A.
name: Van Zandt, Judah
name: Weiss, Lauren M.
name: Knudstrup, Emil
name: Andersen, Mads F.
name: Grundahl, Frank
name: Yao, Xinyu
name: Pepper, Joshua
name: Villanueva, Steven
name: Ciardi, David R.
name: Cloutier, Ryan
name: Jacobs, Thomas Lee
name: Kristiansen, Martti H.
name: LaCourse, Daryll M.
name: Lendl, Monika
name: Osborn, Hugh P.
name: Palle, Enric
name: Stassun, Keivan G.
name: Stevens, Daniel J.
name: Ricker, George R.
name: Vanderspek, Roland
name: Latham, David W.
name: Seager, S.
name: Winn, Joshua N.
name: Jenkins, Jon M.
name: Caldwell, Douglas A.
name: Daylan, Tansu
name: Fong, William
name: Goeke, Robert F.
name: Rose, Mark E.
name: Rowden, Pamela
name: Schlieder, Joshua E.
name: Smith, Jeffrey C.
name: Vanderburg, Andrew
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the detection of a Saturn-size exoplanet orbiting HD 332231 (TOI 1456) in light curves from the Transiting Exoplanet Survey Satellite (TESS). HD 332231, an F8 dwarf star with a V-band magnitude of 8.56, was observed by TESS in Sectors 14 and 15. We detect a single-transit event in the Sector 15 presearch data conditioning (PDC) light curve. We obtain spectroscopic follow-up observations of HD 332231 with the Automated Planet Finder, Keck I, and SONG telescopes. The orbital period we infer from the radial velocity (RV) observations leads to the discovery of another transit in Sector 14 that was masked by PDC due to scattered light contamination. A joint analysis of the transit and RV data confirms the planetary nature of HD 332231 b, a Saturn-size ($0.867^{+0.027}_{-0.025} \; R_{\rm J}$), sub-Saturn-mass ($0.244\pm0.021 \; M_{\rm J}$) exoplanet on a 18.71 day circular orbit. The low surface gravity of HD 332231 b and the relatively low stellar flux it receives make it a compelling target for transmission spectroscopy. Also, the stellar obliquity is likely measurable via the Rossiter-McLaughlin effect, an exciting prospect given the 0.14 au orbital separation of HD 332231 b. The spectroscopic observations do not provide substantial evidence for any additional planets in the HD 332231 system, but continued RV monitoring is needed to further characterize this system. We also predict that the frequency and duration of masked data in the PDC light curves for TESS Sectors 14-16 could hide transits of some exoplanets with orbital periods between 10.5 and 17.5 days.
description: 17 pages, 9 figures, 4 tables. Published in the Astronomical Journal