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

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

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


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+0.027RJ), sub-Saturn-mass (0.244±0.021MJ) 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.

Original languageEnglish (US)
Article number239
JournalAstronomical Journal
Issue number5
StatePublished - May 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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