Stellar Variability in the Orion Nebular Cluster Region from the Chandra HETG Very Large Program Dataset

We report on a variability study of 46 sources in the Orion nebula, observed with the Chandra HETG system and analyzed in the zeroth order. Covering a timespan of 20 years, the HETG observations of this crowded region contain hundreds of overlapping spectral dispersion arms, so we used software developed by a team member to identify any zeroth order images that are confused with overlapping data from another source. Confused zeroth order sources were then removed from the analysis. Examples of light curves of these “clean” zeroth order counts are presented here. Using these clean light curves, we searched for periods using a Lomb-Scargle algorithm, and also developed a method to identify candidate flares within the dataset. More than 100 individual candidate flares have been identified, with most of the 46 sources showing multiple flares in the data, based on sigma filtering.