Search for star-planet interaction

TL;DR

This study investigates the relationship between stellar chromospheric activity and exoplanet orbital parameters, revealing a significant correlation especially for planets with short orbital periods around cooler stars.

Contribution

It provides the first evidence of a correlation between Ca II K line emission and exoplanet orbital period, highlighting a potential star-planet interaction mechanism.

Findings

Stronger Ca II K emission in stars with planets having P_orb < 20 days

Significant dependence of chromospheric activity on orbital period for T_eff < 5500 K

A marked change in activity behavior at P_orb=20 days

Abstract

We analyse the chromospherical activity of stars with extrasolar planets and search for a possible correlation between the equivalent width of the core of Ca II K line and orbital parameters of the planet. We found a statistically significant evidence that the equivalent width of the Ca II K line reversal, which originates in the stellar chromosphere depends on the orbital period P_orb of the exoplanet. Planets orbiting stars with T_eff < 5500 K and with P_orb < 20 days generally have much stronger emission than planets at similar temperatures but at longer orbital periods. P_orb=20 days marks a sudden change in behaviour, which might be associated with a qualitative change in the star-planet interaction.