Orion Nebula YSO IR Properties

Using COUP data, the authors studied in their reference paper the X-ray properties of stars in the Orion Nebula Cluster (ONC) in different evolutionary classes: luminosities, hydrogen column densities N<sub>H</sub>, effective plasma temperatures, and time variability were compared to understand if the interaction between the circumstellar material and the central object can influence the X-ray emission.

They have assembled the deepest and most complete photometric catalog of objects in the ONC region from the UV to 8 microns (µm) using data from the HST Treasury Program; deep and almost simultaneous UBVI and JHK images taken, respectively, with WFI at ESO 2.2m and ISPI at CTIO 4m telescopes; and Spitzer IRAC imaging. They selected high-probability candidate Class 0-I protostars, a sample of "bona fide" Class II stars, and a set of Class III stars with IR emission consistent with normal photospheres.