A&A 477, 309-314 (2008)
Influence of the evolving stellar X-ray luminosity distribution on exoplanetary mass lossT. Penz1, G. Micela1, and H. Lammer2
1 INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
2 Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
(Received 27 July 2007 / Accepted 28 September 2007 )
Aims.We investigate the influence of high-energy stellar radiation at close-in orbits on atmospheric mass loss during the stellar evolution of a G-type star.
Methods.High-energy stellar luminosity varies over a wide range for G field stars. The X-ray luminosity distributions from the Pleiades, the Hyades, and the field are used to derive a scaling law for the evolution of the stellar X-ray luminosity distribution. A modified energy-limited escape approach is taken for calculating atmospheric mass loss for a broad range of planetary parameters.
Results.We show that the evolution of close-in exoplanets strongly depends on the detailed X-ray luminosity history of their host stars, which varies over several orders-of-magnitude for G stars. Stars located in the high-energy tail of the luminosity distribution can evaporate most of its planets within 0.5 AU, while a significant fraction of planets can survive if exposed to a moderate X-ray luminosity. We show the change on an initial planetary mass distribution caused by atmospheric escape.
Key words: planetary systems -- stars: activity -- X-rays: stars -- star: coronae
© ESO 2007