Star Formation and Young Population of the HII Complex Sh2-294

TL;DR

This study investigates the star formation history of the Sh2-294 HII region using infrared observations, identifying young stellar objects and suggesting that star formation is likely triggered by the expansion of the region.

Contribution

The paper provides a detailed analysis of the young stellar population in Sh2-294 using IRAC data and SED modeling, revealing the presence of both low-mass and massive YSOs and proposing a second-generation star formation scenario.

Findings

Identified 36 YSO candidates with IRAC color-color diagrams.

Class I sources are located at the outskirts and are younger than Class II sources.

Detected a massive (~9 solar masses) YSO embedded in a highly extincted cloud.

Abstract

The Sh2-294 HII 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 the region seems to be quite complex. In this paper, we present follow-up results of Sh2-294 HII region at 3.6, 4.5, 5.8, and 8.0 microns observed with the Spitzer Space Telescope Infrared Array Camera (IRAC), coupled with H2 (2.12 microns) observation, to characterize the young population of the region and to understand its star formation history. We identified 36 young stellar object (YSO, Class I, Class II and Class I/II) candidates using IRAC color-color diagrams. It is found that Class I sources are preferentially located at the outskirts of the HII 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 solar masses) YSOs; however, we also detected a massive YSO (~9 solar masses) of Class I nature, embedded in a cloud of visual extinction of ~24 mag. Present analysis suggests that the Class I sources are indeed younger population of the region relative to Class II sources (age ~ 4.5 x 10^6 yr). We suggest that the majority of the Class I sources, including the massive YSOs, are second-generation stars of the region whose formation is possibly induced by the expansion of the HII region powered by a ~ 4 x 10^6 yr B0 main-sequence star.