a1 Institute of Physics/IGAM, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
a2 Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
a3 Institut de Ciències de l'Espai (CSIC-IEEC), Facultat de Ciències, Torre C5, parell, 2a pl, Campus UAB, 08193 Bellaterra, Spain
Stellar X-ray and extreme ultraviolet (XUV) radiation is an important driver of the escape of planetary atmospheres. Young stars emit high XUV fluxes that decrease as they age. Since the XUV emission of a young star can be orders of magnitude higher compared to an older one, this evolution has to be taken into account when studying the mass-loss history of a planet. The temporal decrease of activity is closely related to the operating magnetic dynamo, which depends on rotation and convection in Sun-like stars. Using a sample of nearby M dwarfs, we study the relations between age, rotation and activity and discuss the influence on planets orbiting these low-mass stars.
(Received May 24 2010)
(Accepted July 20 2010)
(Online publication August 19 2010)