STAR FORMATION IN THE COMETARY GLOBULE ORI I-2
- Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)
- SOFIA-USRA, NASA Ames Research Center, MS 211-3, Moffett Field, CA 94035 (United States)
We investigate the young stellar population in and near the cometary globule Ori I-2. The analysis is based on deep Nordic Optical Telescope R-band and Halpha images, JCMT SCUBA 450 and 850 mum images combined with near-infrared Two Micron All Sky Survey (2MASS) photometry and mid-infrared archival Spitzer images obtained with the Infrared Array Camera (IRAC; 3.6, 4.5, 5.8, and 8 mum), and MIPS (24 and 70 mum) instruments. We identify a total of 125 sources within the 5'x5' region imaged by the IRAC. Of these sources, 87 are detected in the R-band image and 51 are detected in the 2MASS. The detailed physical properties of the sources are explored using a combination of near/mid-infrared color-color diagrams, graybody fitting of spectral energy distributions (SEDs) and an online SED fitting tool that uses a library of two-dimensional radiation transfer based accretion models of young stellar objects with disks. Ori I-2 shows clear evidence of triggered star formation with four young low-luminosity pre-main-sequence (PMS) stars embedded in the globule. At least two, possibly as many as four, additional low-mass PMS objects were discovered in the field which are probably part of the young sigma Orionis cluster. Among the PMS stars which have formed in the globule, MIR-54 is a young, deeply embedded Class 0/I object; MIR-51 and 52 are young Class II sources, while MIR-89 is a more evolved, heavily extincted Class II object with its apparent colors mimicking a Class 0/I object. The Class 0/I object MIR-54 coincides with a previously known IRAS source and is a strong submillimeter source. It is most likely the source for the molecular outflow and the large parsec-scale Herbig-Haro (HH) flow. However, the nearby Class II source, MIR-52, which is strong a Halpha emission line star, also appears to drive an outflow approximately aligned with the outflow from MIR-54, and because of the proximity of the two outflows, either star could contribute. MIR-89 appears to excite a low-excitation HH object, HH 992, discovered for the first time in this study.
- OSTI ID:
- 21378131
- Journal Information:
- Astrophysical Journal, Vol. 706, Issue 1; Other Information: DOI: 10.1088/0004-637X/706/1/896; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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