X-ray Flares Observed from Six Young Stars Located in the Region of Star Clusters NGC 869 and IC 2602

摘要

We present, for the first time, an analysis of seven intense X-ray flares observed from six stars (LAV 796, LAV 1174, SHM2002 3734, 2MASS 02191082+5707324, V553 Car, V557 Car). These stars are located in the region of young open star clusters NGC 869 and IC 2602. These flares detected in the XMM-Newton data show a rapid rise (10-40 min) and a slow decay (20-90 min). The X-ray luminosities during the flares in the energy band 0.3-7.5 keV are in the range of 10~(29.9) to 10~(31.7) erg s~(?1). The strongest flare was observed with the ratio ～13 for count rates at peak of the flare to the quiescent intensity. The maximum temperature during the flares has been found to be ～100 MK. The semi-loop lengths for the flaring loops are estimated to be of the order of 1010 cm. The physical parameters of the flaring structure, the peak density, pressure and minimum magnetic field required to confine the plasma have been derived and found to be consistent with flares from pre-main sequence stars in the Orion and the Taurus-Auriga-Perseus region.