Star formation and young population of the hii complex Sh2-294

Abstract

The Sh2-294 H II region ionized by a single B0V star features several infrared excess sources, a photodissociation region, and also a group of reddened stars at its border. The star formation scenario in this region seems to be quite complex. In this paper, we present follow-up results of Sh2-294 H II region at 3.6, 4.5, 5.8, and 8.0 μm observed with the Spitzer Space Telescope Infrared Array Camera (IRAC), coupled with H2 (2.12 μm) observation, to characterize the young population of the region and to understand its star formation history. We identified 36 young stellar object (YSO, ClassI, ClassII, and ClassI/II) candidates using IRAC color-color diagrams. It is found that ClassI sources are preferentially located at the outskirts of the H II region and associated with enhanced H2 emission; none of them are located near the central cluster. Combining the optical to mid-infrared (MIR) photometry of the YSO candidates and using the spectral energy distribution fitting models, we constrained stellar parameters and the evolutionary status of 33 YSO candidates. Most of them are interpreted by the model as low-mass (<4 M⊙) YSOs; however, we also detected a massive YSO (9 M⊙) of ClassI nature, embedded in a cloud of visual extinction of 24 mag. Present analysis suggests that the ClassI sources are indeed a younger population of the region relative to ClassII sources (age 4.5 × 106yr). We suggest that the majority of the ClassI sources, including the massive YSOs, are second-generation stars of the region whose formation is possibly induced by the expansion of the H II region powered by a 4 × 106yr B0 main-sequence star. © 2012 The American Astronomical Society. All rights reserved.