2005/06/21 by Eric D. Feigelson, Konstantin Getman, Leisa Townsley +6 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Emission nebula #Luminosity #Luminosity function #Nebula #Orion Nebula #Population #Star formation #Stars #Stellar population #Stellar, planetary, and galactic studies #Young stellar object #astro-ph
paper · pdf · doi:10.1086/432512
published as Astrophys.J.Suppl.160:379-389,2004 · Accepted for publication in the Astrophysical Journal Supplements, Special Issue on the Chandra Orion Ultradeep Project (COUP). 11 pages, 7 figures. See http://www.astro.psu.edu/coup for an overview of COUP
arxiv created 2005/06/21 · openalex publication_date 2005/09/28 · arxiv updated 2014/10/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Based on the Chandra Orion Ultradeep Project (COUP) observation, we establish the global X-ray properties of the stellar population associated with the Orion Nebula. Three components contribute roughly equally to the integrated COUP luminosity in the hard (2-8 keV) X-ray band: several OB stars, 822 lightly obscured cool stars in the Orion Nebula Cluster (ONC), and 559 heavily obscured stars. ONC stars 0.5-2 pc from the center show a spatial asymmetry consistent with violent relaxation in the stellar dynamics. The obscured COUP sources concentrate around both OMC-1 molecular cores; these small-scale structures indicate ages t ≲ 0.1 Myr. The X-ray luminosity function (XLF) of the lightly obscured sample is roughly lognormal in shape. The obscured population is deficient in lower luminosity stars, perhaps due to localized circumstellar material. Mass-stratified XLFs show that one-third of the Orion Nebula region hard-band emission is produced by the bright O6 star θ 1 Ori C and half is produced by lower mass pre-main-sequence stars with masses 0.3 M ☉ < M < 3 M ☉ . Very low mass stars contribute little to the cluster X-ray emission. Using the hard band emission, we show that young stellar clusters like the ONC can be readily detected and resolved with Chandra across the Galactic disk, even in the presence of heavy obscuration. The Orion Nebula sample is a valuable template for studies of distant clusters. For example, the peak of the XLF shape can serve as a standard candle for a new distance measure to distant young stellar clusters, and the presence of a neon emission line complex around 1 keV can serve as a diagnostic for young stars.