Stellar activity and Lithium abundances in exoplanets host stars

PABLO MAUAS; FLORES, M.; ANDREA BUCCINO; CARLOS SAFFE

Moscú

Congreso; 40th COSPAR Scientific Assembly; 2014

Lomonosov Moscow State University

Recent observations suggest that stellar magnetic activity of FGK stars may be influenced by the presence of a close-by giant planet. Different processes for Star-Planet Interaction (SPI) have been put forward. Magnetic and Tidal interactions could increase the stellar activity level in the host stars. However, there is not a full agreement in the literature associated with the increase in the activity level shown by the host star. To investigate the reason for these phenomena, we analyzed the possible relation between stellar activity and some planetary parameters (semi-major axis, planets masses). Our observations were made at the 2.15 mtelescope of the Complejo Astronómico El Leoncito (CASLEO), which is located at 2552 m above sea level in the Argentinean Andes. We used the REOSC spectrograph to obtain a series of mid-resolution spectra(R ∼ 13000). To study the long-term activity of exoplanet host stars, we used as activity indicator the well known Mount Wilson index (S). Furthermore, we took cuasisimultaneous spectra of stars without planets with the same spectral class, to compare activity levels.On the other hand, we focused on the possible excess of Lithium (Li) depletion found in stars with planets in comparison to similar stars (same range of Tef f and log g) without planets. Moreover, we analyzed thepossible relation between Li abundances and the stellar activity suggested by some authors. To do so, we used high-resolution spectra (R ∼ 110.000) of FGK stars with and without planets taken with the HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph, installed at the 3.6 m ESO telescope.