Long-term activity in dM stars

MAUAS, PABLO J. D.; BUCCINO, ANDREA P.; DÍAZ, RODRIGO F.

Porto, Portugal

Workshop; An ESO-CAUP workshop on:Towards Other Earths.; 2009

ESO

M dwarf stars, due to their low mass, are natural targets to search for Earth-like planets.Furthermore, it has recently been recognized that terrestrial-type planets orbiting dM starsin the liquid-water habitable zones can be suitable places for the emergence and evolution oflife. However, dM stars can be very active, giving rise to large flares. Unfortunately, due totheir low intrinsic brightness, these stars are not usually the target of long-term observationalstudies of stellar activity, and therefore their long-term variability is usually not known.A decade ago we started one such long-term program, to obtain spectra of a number ofstars, with special interest in dM stars. These observations allowed us to find periods in twosuch stars (Prox Cen and Gl 375). Here we report our results on other dM stars, combiningour spectroscopic observations with photometric data.