Presentation #103.07 in the session Star Formation — iPoster Session.
We present an HST 1.6-micron survey in the NGC 2024 cluster of the Orion B region. This is one of the richest embedded clusters within 500 pc from the Sun. The observations are done with HST WFC3 instrument with the F160W filter using the observation method called DASH (”Drift-And-SHift’). The image covers a 15’ × 17’ area in the sky with a resolution of 100 AU. Using these data, we search for multiple systems toward the YSOs previously discovered in Spitzer and Chandra surveys of the cluster. We count the number of companions in the 150-500 AU range, correcting for the line of sight contamination by measuring the density of sources at larger radii. Using artificial star tests, we also determine the completeness of the data as a function of separation and magnitude difference between the primary and the companion. An HST WFC3 IR 1.6-micron survey of Orion YSOs found a companion fraction (CF) of ~13% between 100-1000 AU in less dense regions of the Orion molecular clouds (Kounkel et al. 2016). But earlier HST NICMOS results show ~3% CF in the dense NGC 2024 cluster (Liu et al.2003). With our data, we will test whether the CF in NGC 2024 is significantly smaller than the lower density environments in Orion. A small CF would be strong evidence for stripping of companions in dense environments.