A Search for Young Stellar Objects for the PASHION Mission

Optical emission from embedded young stellar objects (YSOs) in the Galactic plane is obscured by dust. The future PASHION small satellite telescope mission will be able to see through this dust using the hydrogen recombination line Paschen Alpha (Pa α; 1.87 microns). This Pa α emission should also be able to differentiate YSOs from contaminant objects like asymptotic giant branch stars, cataclysmic variables, and Be stars using the emission line excess that YSOs display when combined with wideband infrared photometry in color-color and color-magnitude diagrams. To prepare for the PASHION survey, we searched for existing catalogs of stars in another hydrogen emission line, Hα. While Hα observations of large numbers of YSOs have been performed for years, we did not find any publicly accessible surveys of YSOs which were systematic, narrowband, and photometric. Several groups are working to change this in projects like the Accretion Disks in Hα with OMEGACam (ADHOC) Survey (Beccari et al. 2018). We have identified several YSO samples which would be good targets for systematic hydrogen line surveys to measure their accretion rates.