First observation of planet-induced X-ray emission: The system HD 179949

Abstract

We present the first observation of planet-induced stellar X-ray activity, identified for the HD 179949 system, using Chandra / ACIS-S. The HD 179949 system consists of a close-in giant planet orbiting an F9 V star. Previous ground-based observations already showed enhancements in Ca II K in phase with the planetary orbit. We find an 30% increase in the X-ray flux over quiescent levels coincident with the phase of the Ca II enhancements. There is also a trend for the emission to be hotter at increased fluxes, confirmed by modeling, showing the enhancement at 1 keV compared to 0.4 keV for the background star. © 2008 International Astronomical Union.