Signatures of stellar mass ejections at radio and FUV wavelengths - implications for planetary mass loss

Highly energetic activity phenomena such as flares and Coronal Mass Ejections (CMEs) lead to thermal and non-thermal planetary atmospheric mass loss. Knowledge of stellar CME parameters is poor, therefore the aim of the first part of the thesis is the detection of signatures of stellar CMEs from which parameters can be derived, which can then be used to model non-thermal planetary atmospheric mass loss. Two different approaches have been established. For approach 1 the correlation of decameter type II radio bursts and CMEs on the Sun was extrapolated to stars. Ten nights of observations from the UTR-2 decameter array of the dMe star AD Leo were analysed and a handful of possible stellar type III-like bursts were detected, but no type II-like bursts. For approach 2 the Doppler shift of spectral lines was used as a signature of stellar CMEs. Several hours of far ultraviolet data of the active stars AD Leo, AU Mic, and AB Dor were searched for such signatures. Only AD Leo revealed one spectral line asymmetry in the blue wing of the first component of the OVI duplet at 1032 A shifted by -84 km/s two hours after a flare. In addition the electron density-sensitive line ratio CIII(1176 A)/CIII(977 A) was investigated and found to be enhanced during stellar flaring. This finding was also investigated on the Sun where a similar behaviour for powerful solar flares was found. Due to a lack of coinciding data a correlation of the carbon ion line ratio and CMEs could not be investigated. In the second part of the thesis the thermal planetary atmospheric mass loss was investigated theoretically and found to be most efficient for close-in low density planets. By using a modified energy-limited approach the thermal mass loss of the recently discovered Super-earths CoRoT-7b and Kepler-10b was calculated and found to be in the order of one earth mass. Therefore it is concluded that both planets cannot be the remnants of Jupiter- or Saturn-sized gas giants. (author)