Detailed Stellar and Planetary Characterization of the Multiplanet Systems Kepler-278 and Kepler-391

EMILIANO JOFRÉ; JOSÉ ALMENARA; ROMINA PETRUCCI; RODRIGO DÍAZ; YILEN GÓMEZ MAQUEO CHEW; EDER MARTIOLI; IVAN RAMÍREZ; LUCIANO GARCÍA; CARLOS SAFFE; ELIAB CANUL CANCHÉ; ANDREA BUCCINO; MERCEDES GÓMEZ

Workshop; 2020 Sagan Summer Workshop; 2020

Kepler-278 and Kepler-391 are two of the three evolved stars known to date on the red giant branch (RGB) to host multiple short-period transiting planets. Moreover, the planets orbiting Kepler-278 and Kepler-391 are among the smallest discovered around RGB stars. Here we present a detailed stellar and planetary characterization of these remarkable systems. Based on high-quality spectra, we obtained refined stellar parameters and precise chemical abundances for 25 elements. Nine of these elements and the carbon isotopic ratios, had not previously been measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. In particular, for Kepler-278, thanks to the presence of dynamical interactions in the system, we constrained, for the first time, the masses of the two planets.