STAR FORMATION ACTIVITY IN THE GALACTIC H II COMPLEX S255-S257

Journal Article · Sat Sep 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/738/2/156; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21584867

Ojha, D K; Ghosh, S K ^[1]; Samal, M R; Pandey, A K; Sharma, Saurabh ^[2]; Bhatt, B C ^[3]; Tamura, M ^[4]; Mohan, V ^[5]; Zinchenko, I ^[6]

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1. Tata Institute of Fundamental Research, Mumbai (Bombay) 400 005 (India)
2. Aryabhatta Research Institute of Observational Sciences, Nainital 263 129 (India)
3. Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India)
4. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
5. Inter-University Centre for Astronomy and Astrophysics, Pune 411 007 (India)
6. Institute of Applied Physics of the Russian Academy of Sciences, Ulyanova 46, 603950 Nizhny Novgorod (Russian Federation)

We present results on the star formation activity of an optically obscured region containing an embedded cluster (S255-IR) and molecular gas between two evolved H II regions, S255 and S257. We have studied the complex using optical and near-infrared (NIR) imaging, optical spectroscopy, and radio continuum mapping at 15 GHz, along with Spitzer-IRAC results. We found that the main exciting sources of the evolved H II regions S255 and S257 and the compact H II regions associated with S255-IR are of O9.5-B3 V nature, consistent with previous observations. Our NIR observations reveal 109 likely young stellar object (YSO) candidates in an area of {approx}4.'9 x 4.'9 centered on S255-IR, which include 69 new YSO candidates. To see the global star formation, we constructed the V - I/V diagram for 51 optically identified IRAC YSOs in an area of {approx}13' x 13' centered on S255-IR. We suggest that these YSOs have an approximate age between 0.1 and 4 Myr, indicating a non-coeval star formation. Using spectral energy distribution models, we constrained physical properties and evolutionary status of 31 and 16 YSO candidates outside and inside the gas ridge, respectively. The models suggest that the sources associated with the gas ridge are younger (mean age {approx}1.2 Myr) than the sources outside the gas ridge (mean age {approx}2.5 Myr). The positions of the young sources inside the gas ridge at the interface of the H II regions S255 and S257 favor a site of induced star formation.

• OSTI ID: 21584867
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 738; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ENERGY SPECTRA
EVOLUTION
GEOLOGIC SURVEYS
GEOPHYSICAL SURVEYS
INFRARED SURVEYS
PHYSICAL PROPERTIES
SIMULATION
SPECTRA
STAR CLUSTERS
STAR EVOLUTION
STARS