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J/ApJ/706/896    Photometry in the cometary globule Ori I-2   (Mookerjea+, 2009)

Star formation in the cometary globule Ori I-2. Mookerjea B., Sandell G. <Astrophys. J., 706, 896-908 (2009)> =2009ApJ...706..896M
ADC_Keywords: Photometry, infrared ; Molecular clouds ; H II regions ; Stars, pre-main sequence Keywords: dust, extinction - H II regions - ISM: clouds - stars: formation - stars: pre-main sequence Abstract: 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 Hα images, JCMT SCUBA 450 and 850um 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 8um), and MIPS (24 and 70um) 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. 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 σ 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 Hα 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. Description: We have extracted IRAC and MIPS observations from the Spitzer Space Observatory archive (Program ID 30050: Star Formation in Bright Rimmed Clouds, PI: G. Fazio). The optical CCD images presented here were obtained on 2007 October 26 using the 2.56m Nordic Optical Telescope (NOT) located at El Observatorio del Roque de Los Muchachos on the island of La Palma in the Canary Islands. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 128 125 Mid infrared sources in Ori I-2
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/A+A/510/A1 : Near infrared imaging of cometary globule CG12 (Haikala+, 2010) J/A+A/507/1485 : Young (proto)stellar population in L1630 (Mookerjea+ 2009) J/ApJS/175/277 : Submillimeter-Continuum SCUBA detections (Di Francesco+, 2008) J/ApJ/674/336 : Spitzer observations of NGC 1333 (Gutermuth+, 2008) J/AJ/135/2323 : Hα stars and HH objects near BRCs (Ikeda+, 2008) J/ApJ/669/327 : S3MC: YSOs in N66, in SMC (Simon+, 2007) J/MNRAS/276/57 : IRAS Galactic star-forming regions. II. (Codella+ 1995) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [MIR-] 5- 7 I3 --- MIR [1-125] Ori I-2 MIR source number (<[MS2009c] MIR-NNN> in Simbad) 9 I1 h RAh Hour of right ascension (J2000) 11- 12 I2 min RAm Minute of right ascension (J2000) 14- 18 F5.2 s RAs Second of right ascension (J2000) 20 A1 --- DE- Sign of declination (J2000) 21 I1 deg DEd Degree of declination (J2000) 23- 24 I2 arcmin DEm Arcminute of declination (J2000) 26- 29 F4.1 arcsec DEs Arcsecond of declination (J2000) 31 A1 --- f_Rmag [S] S: saturated; Flag for MIR-73 (1) 32- 35 F4.1 mag Rmag ? Nordic Optical Telescope R-band magnitude 37- 41 F5.2 mag Jmag ? 2MASS J-band magnitude 43- 46 F4.2 mag e_Jmag ? Jmag uncertainty 48- 52 F5.2 mag Hmag ? 2MASS H-band magnitude 54- 57 F4.2 mag e_Hmag ? Hmag uncertainty 59- 63 F5.2 mag Ksmag ? 2MASS Ks-band magnitude 65- 68 F4.2 mag e_Ksmag ? Ksmag uncertainty 70- 74 F5.2 mJy F3.6 ? Spitzer/IRAC 3.6um band flux 75 A1 --- f_F3.6 [ab] Near the edge or outside 3.6um map (2) 77- 80 F4.2 mJy e_F3.6 ? F3.6 uncertainty 82- 86 F5.2 mJy F4.5 ? Spitzer/IRAC 4.5um band flux 88- 91 F4.2 mJy e_F4.5 ? F4.5 uncertainty 93- 97 F5.2 mJy F5.8 ? Spitzer/IRAC 5.8um band flux 98 A1 --- f_F5.8 [a] outside the 5.8um map (2) 100-103 F4.2 mJy e_F5.8 ? F5.8 uncertainty 105-109 F5.2 mJy F8.0 ? Spitzer/IRAC 8.0um band flux 111-114 F4.2 mJy e_F8.0 ? F8.0 uncertainty 116-121 F6.2 mJy F24 ? Spitzer/MIPS 24um band flux 123-126 F4.2 mJy e_F24 ? F24 uncertainty 128 A1 --- n_MIR [*] *: candidate pre-main sequence star further discussed in text and table 3
Note (1): The bright star located ∼43" away from MIR-54 in the color image is SAO 132389 (HD 37389). This star, identified as MIR-73 in Table 1, is detected even at 24um, although it is an unreddened foreground A0 star with an mV=8.3mag. The star has a radial velocity of ∼21km/s, which is very different from the radial velocity (12km/s) of Ori I-2 (Cernicharo et al. 1992A&A...261..589C). Note (2): Flag as follows: a = Outside the area mapped in 3.6 and 5.8um. b = The star is at the edge of the 3.6um map and only partially detected.
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 14-Dec-2011
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