Activity-rotation relation in the young cluster h Per

Abstract

The activity-rotation relation in PMS stars is still an open issue. To bridge the gap between the well constrained case of MS stars and the puzzling case of very young PMS stars, we studied the activity-rotation relation in the young cluster h Persei. Because of its age (˜13 Myr) h Per contains both fast and slow rotators, allowing us therefore to test the different regimes of stellar dynamo. We analyzed a deep Chandra/ACIS-I observation to constrain the activity level of h Per members. Rotational periods were derived by tet{MorauxArtemenko2013}. From the comparison of the 1002 detected X-ray sources, and the 586 h Per members with measured rotational period, we obtained a final catalog of 169 h Per members with measured X-ray luminosity (ranging between 3.5×10^{29} and 1.1×10^{31} {erg s^{-1}}), rotational period (ranging between 0.22 and 15.9 d), and mass (ranging between 0.2 and 1.8 {M_{⊙}}). We find clear evidence for supersaturation in stars with mass between 1.0 and 1.6 M_{⊙}. This phenomenon is unobserved for lower mass stars.