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Chandra X-Ray Observations of Young Clusters. II. Orion Flanking Fields Data

2004; Institute of Physics; Volume: 128; Issue: 2 Linguagem: Inglês

10.1086/422349

1538-3881

Solange Ramírez, L. M. Rebull, J. R. Stauffer, S. E. Strom, Lynne A. Hillenbrand, Thomas Hearty, E. L. Kopan, S. H. Pravdo, Russell B. Makidon, B. F. Jones,

Astro and Planetary Science

We present results of Chandra observations of two flanking fields (FFs) in Orion, outside the Orion Nebula Cluster (ONC). The observations were taken with the ACIS-I camera with an exposure time of about 48 ks each field. We present a catalog of 417 sources, which includes X-ray luminosity, optical and infrared photometry, and X-ray variability information. We have found 91 variable sources, 33 of which have a flarelike light curve and 11 of which have a pattern of a steady increase or decrease over a 10 hr period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being pre–main-sequence stars with ages younger than 10 Myr. We present evidence for an age difference among the X-ray–selected samples of NGC 2264, Orion FFs, and ONC, with NGC 2264 being the oldest and ONC being the youngest.