Stellar and planetary characterization of Kepler multi-planet systems from high-quality Gemini/GRACES spectra

E. JOFRÉ; R. PETRUCCI , E., JOFRÉ, L.V. FERRERO, V. CÚNEO, L. SAKER, F. LOVOS, M. GOMEZ, P. MAUAS; Y. GÓMEZ MAQUEO CHEW; R. F. DÍAZ ; C. SAFFE ; M. GOMEZ

Puerto Vallarta

Congreso; New quests in stellar astrophysics IV Astrochemistry, Astrobiology and the origin of Life; 2019

INAOE - CONACYT

Radial velocity surveys have revealed a dearth of close-in planets (a < 0.5 AU; P < 100 days) around evolved stars. Close-in planets might be destroyed as they spiral into their host stars as a result of tidal interactions. Alternatively, planet formation and evolution mechanisms around more massive stars could produce a lower frequency of short-period gas giant planets. To date, based on high-precision Kepler photometry, only a handful of close-in (0.06 < a < 0.3 AU) transiting planets have been discovered around evolved stars on the red giant branch. Detailed characterization of these planetary systems is crucial for constraining models of planet-star interaction and planet formation in stars more massive than the Sun. In this context, we present a detailed stellar and planetary study of the exceptional systems Kepler-278 and Kepler-391. These are two of the only four multi-planet systems known to date that transit RGB (Red Giant Brach) stars. Our characterization includes the first determination of refined stellar parameters and precise photospheric chemical abundances based on high-quality spectra. In addition, from our newly measured stellar parameters, we obtained improved planetary properties.