A DETAILED SPECTROPOLARIMETRIC ANALYSIS OF THE PLANET-HOSTING STAR WASP-12

The knowledge of accurate stellar parameters is paramount in several fields of stellar astrophysics, particularly in the study of extrasolar planets, where often the star is the only visible component and therefore used to infer the planet's fundamental parameters. Another important aspect of the analysis of planetary systems is the stellar activity and the possible star-planet interaction. Here, we present a self-consistent abundance analysis of the planet-hosting star WASP-12 and a high-precision search for a structured stellar magnetic field on the basis of spectropolarimetric observations obtained with the ESPaDOnS spectropolarimeter. Our results show that the star does not have a structured magnetic field, and that the obtained fundamental parameters are in good agreement with what was previously published. In addition, we derive improved constraints on the stellar age (1.0-2.65 Gyr), mass (1.23-1.49 M/Msun), and distance (295-465 pc). WASP-12 is an ideal object in which to look for pollution signatures in the stellar atmosphere. We analyze the WASP-12 abundances as a function of the condensation temperature and compare them with those published by several other authors on planet-hosting and non-planet-hosting stars. We find hints of atmospheric pollution in WASP-12's photosphere but are unable to reach firm conclusions with our present data. We conclude that a differential analysis based on WASP-12 twins will probably clarify whether an atmospheric pollution is present as well as the nature of this pollution and its implications in planet formation and evolution. We also attempt the direct detection of the circumstellar disk through infrared excess, but without success.