X-ray emission from young stars in the Tucanae association

Abstract

We report on X-ray emission from members of the recently discovered Tucanae association, a group of stars with youth signatures and similar space motion. The Tucanae association is the nearest known region of recent star formation (at 45 pc) far from molecular clouds. We have made use of the ROSAT Data Archive, and searched for X-rays from Tucanae stars in both ROSAT All-Sky Survey (RASS) and pointed observations. The RASS detection rate for the Tucanae members is 59%. We compare the X-ray luminosity function of the Tucanae association to that of other star forming regions and young star clusters. Both the X-ray luminosity function and the strong variability observed in the X-ray lightcurves suggest that the examined stars are young, on the order of 10-30 Myrs.