A Comparative Observational Study of YSO Classification in Four Small Star-forming H ii Regions

Abstract

We have developed a new young stellar object (YSO) identification and classification technique using mid-infrared Wide-field Infrared Survey Explorer (WISE) data. We compare this new technique with previous WISE  YSO detection and classification methods that used either infrared colors or spectral energy distribution slopes. In this study, we also use the new technique to detect and examine the YSO population associated with four small H ii  regions: KR 7, KR 81, KR 120, and KR 140. The relatively simple structure of these regions allows us to effectively use both spatial and temporal constraints to identify YSOs that are potential products of triggered star formation. We are also able to identify regions of active star formation around these H ii  regions that are clearly not influenced by the H ii  region expansion, and thus demonstrate that star formation is on-going on megayear timescales in some of these molecular clouds.