The TESS-Keck Survey. I. A Warm Sub-Saturn-mass Planet and a Caution about Stray Light in TESS Cameras

Dalba, Paul A.; Gupta, Arvind F.; Rodriguez, Joseph E.; Dragomir, Diana; Huang, Chelsea X.; Kane, Stephen R.; Quinn, Samuel N.; Bieryla, Allyson; Esquerdo, Gilbert A.; Fulton, Benjamin J.; Scarsdale, Nicholas; Batalha, Natalie M.; Beard, Corey; Behmard, Aida; Chontos, Ashley; Crossfield, Ian J. M.; Dressing, Courtney D.; Giacalone, Steven; Hill, Michelle L.; Hirsch, Lea A.; Howard, Andrew W.; Huber, Daniel; Isaacson, Howard; Kosiarek, Molly; Lubin, Jack; Mayo, Andrew W.; Mocnik, Teo; Akana Murphy, Joseph M.; Petigura, Erik A.; Robertson, Paul; Rosenthal, Lee J.; Roy, Arpita; Rubenzahl, Ryan A.; Van Zandt, Judah; Weiss, Lauren M.; Knudstrup, Emil; Andersen, Mads F.; Grundahl, Frank; Yao, Xinyu; Pepper, Joshua; Villanueva, Steven, Jr.; Ciardi, David R.; Cloutier, Ryan; Jacobs, Thomas Lee; Kristiansen, Martti H.; LaCourse, Daryll M.; Lendl, Monika; Osborn, Hugh P.; Palle, Enric; Stassun, Keivan G.; Stevens, Daniel J.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Caldwell, Douglas A.; Daylan, Tansu; Fong, William; Goeke, Robert F.; Rose, Mark E.; Rowden, Pamela; Schlieder, Joshua E.; Smith, Jeffrey C.; Vanderburg, Andrew
Bibliographical reference

The Astronomical Journal

Advertised on:
5
2020
Number of authors
66
IAC number of authors
1
Citations
37
Refereed citations
35
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 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}_{-0.025}^{+0.027}\ {R}_{{\rm{J}}} ), sub-Saturn-mass ( $0.244\pm 0.021\ {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.
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Exoplanets and Astrobiology
The search for life in the universe has been driven by recent discoveries of planets around other stars (known as exoplanets), becoming one of the most active fields in modern astrophysics. The growing number of new exoplanets discovered in recent years and the recent advance on the study of their atmospheres are not only providing new valuable
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