The flaring activity of pre-main sequence stars in very young open clusters

Abstract

In this master's thesis, we studied XMM-Newton observations of NGC6530. We found that the rotation rates of the X-ray selected PMS in this cluster were not more important than the ones presented for the full sample of cluster members studied by Henderson & Stassun (2012). We obtained ages between 1.5 and 10 Myr, and masses ranging from 0.5 to 1.0 solar masses, similar to the ones found in the literature. We found that classical T Tauri stars were outnumbered by the weak-line T Tauri stars, a result that is again in agreement with previous studies of NGC6530 and of other clusters. Out of 352 probables sources, 117 are variable and 4 present flares (only one of which is presumably a cTTs). This number of flares might seem low, but can be compared to similar studies of other young open clusters and to the most energetic flares on the Sun. We found NH values exceeding the values expected for the mean E(B-V). This, along with the fact that lower values of NH are associated with higher values of kT (and vice versa) could stem from the degeneracy between NH and kT.