J/ApJ/755/20 YSOs population of Sh2-294 with Spitzer/IRAC (Samal+, 2012)
Star formation and young population of the H II complex Sh2-294.
Samal M.R., Pandey A.K., Ojha D.K., Chauhan N., Jose J., Pandey B.
<Astrophys. J., 755, 20 (2012)>
=2012ApJ...755...20S 2012ApJ...755...20S
ADC_Keywords: Photometry, infrared ; H II regions ; YSOs ; Stars, masses ;
Stars, ages
Keywords: H II regions; ISM: individual: Sh2-294;
stars: formation; stars: pre-main sequence
Abstract:
The Sh2-294 H II region ionized by a single B0V star features several
infrared excess sources, a photodissociation region, and also a group
of reddened stars at its border. The star formation scenario in this
region seems to be quite complex. In this paper, we present follow-up
results of Sh2-294 H II region at 3.6, 4.5, 5.8, and 8.0µm observed
with the Spitzer Space Telescope Infrared Array Camera (IRAC), coupled
with H2(2.12µm) observation, to characterize the young population
of the region and to understand its star formation history. We
identified 36 young stellar object (YSO, Class I, Class II, and Class
I/II) candidates using IRAC color-color diagrams. It is found that
Class I sources are preferentially located at the outskirts of the H
II region and associated with enhanced H2emission; none of them are
located near the central cluster. Combining the optical to
mid-infrared (MIR) photometry of the YSO candidates and using the
spectral energy distribution fitting models, we constrained stellar
parameters and the evolutionary status of 33 YSO candidates. Most of
them are interpreted by the model as low-mass (<4 M☉) YSOs;
however, we also detected a massive YSO (∼9 M☉) of Class I
nature, embedded in a cloud of visual extinction of ∼24 mag.
Description:
The archived MIR data for the region were obtained with the Infrared
Array Camera (IRAC) on board the Spitzer Space Telescope. The IRAC
observations of the region were taken on 2006 November 25 (Program ID
30734, AOR key 18902784: Massive Star Clusters, PI: Donald Figer).
Restricting our analysis to the sources having photometric error less
than 0.2 mag, we detected 102 sources in the 3.6, 4.5, and 5.8um bands
and 31 sources in all the IRAC bands in a common area of ∼6.8'x6.8'.
These catalogs are made after removing three sources that appear to be
extended and/or multiple sources in the high-resolution H2 (2.12um)
and 3.6um IRAC images. The final catalog used to identify the YSOs in
the present analysis is given in Table 1. The H2 mosaic image was
constructed using the observations made with the ISAAC camera of the
Very Large Telescope (VLT). The data were retrieved from the ESO
archive. Further details about the observations are described in Yun
et al. (2008, Cat. J/A+A/483/209).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 103 Photometric data in IRAC bands
(97 different positions)
table2.dat 97 33 Inferred physical parameters from SED fits to YSOs
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See also:
V/114 : MSX6C Infrared Point Source Catalog (Egan+ 2003)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/50 : CO Radial Velocities Toward Galactic H II Regions (Blitz+ 1982)
J/A+A/483/209 : Phot. of a stellar cluster near IRAS 07141-092 (Yun+, 2008)
J/A+A/470/161 : UBV photometry of HII regions exciting stars (Russeil+, 2007)
J/ApJ/649/759 : Bubbles in the galactic disk (Churchwell+, 2006)
J/A+A/397/213 : Galactic HII regions (Paladini+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg [109.0/109.2] Right Ascension (J2000)
10 A1 --- --- [0]
12- 19 F8.5 deg DEdeg [-9.5/-9.3] Declination (J2000)
20 A1 --- --- [0]
22- 27 F6.3 mag 3.6mag [9.6/15] Spitzer/IRAC 3.6 micron band magnitude
29- 33 F5.3 mag e_3.6mag Uncertainty in 3.6mag
35- 40 F6.3 mag 4.5mag [9.2/14.8] Spitzer/IRAC 4.5um band magnitude
42- 46 F5.3 mag e_4.5mag Uncertainty in 4.5mag
48- 53 F6.3 mag 5.8mag [7.8/14.1] Spitzer/IRAC 5.8um band magnitude
55- 59 F5.3 mag e_5.8mag Uncertainty in 5.8mag
61- 66 F6.3 mag 8.0mag [8.6/12.4]? Spitzer/IRAC 8.0um band magnitude
68- 72 F5.3 mag e_8.0mag [0.02/0.2]? Uncertainty in 8.0mag
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- ID YSO identification (1)
4- 13 F10.6 deg RAdeg [109/109.2] Right ascension (J2000)
15- 23 F9.6 deg DEdeg [-9.5/-9.3] Declination (J2000)
25- 28 F4.2 Msun M [0.6/8.8] Stellar mass
30- 33 F4.2 Msun e_M [0.1/2] Mass uncertainty
35- 39 F5.2 kK T [3.4/16.1] Stellar temperature
41- 44 F4.2 kK e_T [0.1/5] Temperature uncertainty
46- 49 F4.2 Myr Age [0.04/8.1] Stellar age (t*)
51- 54 F4.2 Myr e_Age [0.04/3.3] Age uncertainty
56- 60 F5.3 Msun Mdisk [0/0.2] Disk mass
62- 66 F5.3 Msun e_Mdisk [0/0.3] Mdisk uncertainty
68- 73 F6.2 10-8Msun/yr dM/dt [0/390] Disk accretion rate (dM/dtdisk)
75- 80 F6.2 10-8Msun/yr e_dM/dt [0/383] dM/dt uncertainty
82- 86 F5.2 mag Av [3.1/23.7] Foreground visual absorption
88- 91 F4.2 mag e_Av [0.1/6.7] Av uncertainty
93- 97 F5.2 --- chi2 [0.8/35.9] Best fit χ2min
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Note (1): The IRAC-classified Class II, Class I/II, and Class I YSOs are
labeled with the numbers 1-25, T1-T5, and C1-C3, respectively (see Figure 3).
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History:
From electronic version of the journal
References:
Samal et al. Paper I. 2007ApJ...671..555S 2007ApJ...671..555S
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Mar-2014