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

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