Detection of alpha Centauri at radio wavelengths: chromospheric emission and search for star-planet interaction

Abstract

The Sun is one of the brightest radio source of the sky. However, if we project the Sun at the distance of the nearby stars, its emission is so faint that no radiotelescope or interferometer would have been able so far to detect it at centimetric wavelenghts. Nevertheless the informations that is possible to derive from radio observations are of great importance for the study of stellar atmosfere as well as its surrounding. The new generation of radio interferometers has enough sensitivity to detect the closest solar type system, Alpha Centauri, that we observed with ATCA at 17 and 2.1 GHz. In this talk I’ll present the results of these observations and what is possible to derive about atmospheric profiles and magnetic activity. Another important potentiality is the possibility to detect auroral radio emission generated to the interaction of the stellar magnetosphere and an orbiting planet. Even if the claimed discovery of a Earth planet around Alpha Cen B at the time of our observations is now ruled out, I take the opportunity to discuss the Auroral Radio Emission due to Electron Cyclotron Maser, that could be of great importance to detect planetary magnetic fields, whose presence is importance for the habitability and life protection in Earth-like exoplanets, and our works in progress in this field.