A multiwavelength investigation of the H ii region S311: young stellar population and star formation

• Published in: Monthly notices of the Royal Astronomical Society Vol. 461; no. 3; pp. 2502 - 2518
• Main Authors: Yadav, Ram Kesh, Pandey, A. K., Sharma, Saurabh, Ojha, D. K., Samal, M. R., Mallick, K. K., Jose, J., Ogura, K., Richichi, Andrea, Irawati, Puji, Kobayashi, N., Eswaraiah, C.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 21.09.2016
• Subjects: Astronomy; Borders; Clumps; H II regions; Holes; Spatial distribution; Star & galaxy formation; Star formation; Stellar age; Stellar populations; stars: formation; stars: pre-main sequence; regions; Stars: clusters; ISM: H; ISM: Individual Objects: S311; star clusters: individual (Haffner 18)
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw1356

We present a multiwavelength investigation of the young stellar population and star formation activities around the H ii region Sharpless 311. Using our deep near-infrared observations and archival Spitzer-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of ∼86 arcmin2. The YSO sample includes eight Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSO sample is estimated to be 1.0 M⊙. The ages and masses of the majority of the candidate YSOs are estimated to be in the range ∼0.1–5 Myr and ∼0.3–6 M⊙, respectively. The 8-μm image of S311 displays an approximately spherical cavity around the ionizing source, which was possibly created by the expansion of the H ii region. The spatial distribution of the candidate YSOs reveals that a significant number of them are distributed systematically along the 8-μm emission with a majority clustered around the eastern border of the H ii region. Four clumps/compact H ii regions are detected in the radio continuum observations at 1280 MHz, which may have been formed during the expansion of the H ii region. The estimated dynamical age of the region, main-sequence lifetime of the ionizing source, the spatial distribution and ages of the candidate YSOs indicate triggered star formation in the complex.