A detailed spectropolarimetric analysis of the planet hosting star WASP-12

TL;DR

This study provides a detailed spectropolarimetric analysis of star WASP-12, confirming its fundamental parameters, searching for magnetic fields, and investigating atmospheric pollution and circumstellar material related to its exoplanet system.

Contribution

It offers the first high-precision spectropolarimetric search for magnetic fields on WASP-12 and analyzes stellar pollution signatures, improving parameter constraints and exploring star-planet interactions.

Findings

No structured magnetic field detected on WASP-12

Hints of atmospheric pollution in the star's photosphere

No infrared excess detected for circumstellar disk

Abstract

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/M0), and distance (295-465 pc). WASP-12 is an ideal object to look for pollution signatures in the stellar atmosphere. We analyse 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 if an atmospheric pollution is present, the nature of this pollution and its implications in the planet formation and evolution. We attempt also the direct detection of the circumstellar disk through infrared excess, but without success.