[Previous] | [Session 93] | [Next]
S. Skinner (CASA, Univ. of Colorado), E. Belzer, M. Gagne (West Chester Univ.)
We present results of a 75 ksec Chandra observation of the young (0.3 Myr) stellar cluster NGC 2024 in the Orion region. Previous infrared (IR) studies have detected a large population of embedded young stars in this cluster, most of which are still surrounded by circumstellar disks. Very few of the IR members are optically visible, so X-ray observations provide a crucial check on the completeness of IR surveys.
Chandra detected 283 X-ray sources in the 17 x 17 arc-minute ACIS-I field-of-view, of which 204 were identified with previously known counterparts. Several of the X-ray sources without known counterparts exhibited X-ray flares, suggesting that they are heavily obscured cluster members that have escaped IR detection. The Chandra sources in NGC 2024 are characterized by variable emission and hard, heavily-absorbed X-ray spectra. More than one-half of the detections showed some form of variability, including rapid impulsive flares indicative of magnetic activity as well as more mysterious slow variability. Spectral analysis of more than 100 of the brightest detections yields an average absorption column density NH = 2.3E22 cm-2 (Av ~ 10.5 mag), but a few sources are much more heavily absorbed (Av > 45 mag). Typical X-ray temperatures are kT ~ 3 keV, but flare temperatures in several objects exceeded 5 keV. We present Chandra images and representative X-ray spectra and light curves, and compare properties of the X-ray and IR populations of NGC 2024.
This work was supported by SAO grant GO1-2009A.
[Previous] | [Session 93] | [Next]
Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.