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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 128 125 Mid infrared sources in Ori I-2
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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
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Bytes Format Units Label Explanations
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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
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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 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.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 14-Dec-2011