J/ApJ/759/48 YSOs in the Galactic HII region Sh2-297 (Mallick+, 2012)
Star formation activity in the Galactic H II region Sh2-297.
Mallick K.K., Ojha D.K., Samal M.R., Pandey A.K., Bhatt B.C., Ghosh S.K.,
Dewangan L.K., Tamura M.
<Astrophys. J., 759, 48 (2012)>
=2012ApJ...759...48M 2012ApJ...759...48M
ADC_Keywords: H II regions ; Photometry, VRI ; Photometry, infrared
Keywords: dust, extinction; H II regions; infrared: ISM;
ISM: individual: Sh2-297; radio continuum: ISM; stars: formation
Abstract:
We present a multiwavelength study of the Galactic H II region
Sh2-297, located in the Canis Major OB1 complex. Optical spectroscopic
observations are used to constrain the spectral type of ionizing star
HD 53623 as B0V. The classical nature of this H II region is affirmed
by the low values of electron density and emission measure, which are
calculated to be 756/cm3 and 9.15x105cm-6pc using the radio
continuum observations at 610 and 1280MHz, and Very Large Array
archival data at 1420MHz. To understand local star formation, we
identified the young stellar object (YSO) candidates in a region of
area ∼7.5'x7.5' centered on Sh2-297 using grism slitless spectroscopy
(to identify the Hα emission line stars), and near infrared
(NIR) observations. NIR YSO candidates are further classified into
various evolutionary stages using color-color and color-magnitude (CM)
diagrams, giving 50 red sources (H-K>0.6) and 26 Class II-like
sources. The mass and age range of the YSOs are estimated to be
∼0.1-2M☉ and 0.5-2Myr using optical (V/V-I) and NIR (J/J-H) CM
diagrams. The mean age of the YSOs is found to be ∼1Myr, which is of
the order of dynamical age of 1.07Myr of the H II region. Using the
estimated range of visual extinction (1.1-25mag) from literature and
NIR data for the region, spectral energy distribution models have been
implemented for selected YSOs which show masses and ages to be
consistent with estimated values. The spatial distribution of YSOs
shows an evolutionary sequence, suggesting triggered star formation in
the region. The star formation seems to have propagated from the
ionizing star toward the cold dark cloud LDN1657A located west of
Sh2-297.
Description:
Optical photometric observations were performed using the 2m Himalayan
Chandra Telescope (HCT), Hanle (India), operated by the Indian
Institute of Astrophysics, Bangalore. Long and short exposure
observations were taken in the Bessell V and I filters on 2009 October
21. [SII](6724Å), Hα(6563Å), and [OIII](5007Å) filter
observations, with an integration time of 300s each, were done on 2010
January 18.
The optical spectroscopic observations were carried out using HCT and
the 2m IUCAA Girawali Observatory (IGO) telescope at Girawali near
Pune (India), operated by the Inter University Centre for Astronomy
and Astrophysics (IUCAA), Pune. The HCT data were obtained on 2009
December 21, R∼1200.
NIR observations, centered on RAJ2000∼07:05:11, DEJ2000~-12:18:51 for
the object, in J (1.25um), H (1.63um), and Ks (2.14um) bands, were
carried out on 2007 February 27 using the f/10 Cassegrain 1.4m
Infrared Survey Facility (IRSF) telescope, South Africa with
Simultaneous InfraRed Imager for Unbiased Survey -a three color
simultaneous camera.
1280MHz observation was carried out on 2007 July 12, while that for
610MHz on 2007 July 19, using the Giant Metrewave Radio Telescope
(GMRT) array.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 124 97 Optical and infrared magnitudes for the YSOs
table3.dat 94 28 SED results for the YSOs
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See also:
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
VII/20 : Catalogue of HII Regions (Sharpless 1959)
J/A+A/527/A88 : Chemistry in infrared dark clouds (Vasyunina+, 2011)
J/ApJS/175/277 : Submillimeter-Continuum SCUBA detections (Di Francesco+, 2008)
J/PASJ/56/313 : 13CO survey of Mon + CMa molecular clouds (Kim+, 2004)
J/A+A/404/223 : 2MASS IR star clusters in the Galaxy (Bica+, 2003)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Set Sample (G1)
9- 10 I2 --- Seq [1/97] Running sequence number
(<[MOS2012] NN> in Simbad)
12- 13 I2 h RAh Hour of right ascension (J2000)
15- 16 I2 min RAm Minute of right ascension (J2000)
18- 23 F6.3 s RAs Second of right ascension (J2000)
25 A1 --- DE- Sign of declination (J2000)
26- 27 I2 deg DEd Degree of declination (J2000)
29- 30 I2 arcmin DEm Arcminute of declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of declination (J2000)
38- 42 F5.2 mag Vmag [13.86/20.78]? HCT Bessell V-band magnitude
44- 47 F4.2 mag e_Vmag [0.01/0.14]? Vmag uncertainty
49- 53 F5.2 mag Imag [12.69/17.95]? HCT Bessell I-band magnitude
55- 58 F4.2 mag e_Imag [0.01/0.03]? Imag uncertainty
60- 64 F5.2 mag Jmag [11.67/18.25]? J-band (1.25um) magnitude
66- 69 F4.2 mag e_Jmag [0.01/0.1]? Jmag uncertainty
71- 75 F5.2 mag Hmag [10.83/18.02]? H-band (1.63um) magnitude
77- 80 F4.2 mag e_Hmag [0.01/0.1]? Hmag uncertainty
82- 86 F5.2 mag Ksmag [10.07/16.21]? Ks-band (2.14um) magnitude
88- 91 F4.2 mag e_Ksmag [0.01/0.14]? Ksmag uncertainty
93- 97 F5.2 mag W1mag [9.61/15.72]? WISE W1-band (3.4um) magnitude
99-102 F4.2 mag e_W1mag [0.01/0.27]? W1mag uncertainty
104-108 F5.2 mag W2mag [9.03/14.33]? WISE W2-band (4.6um) magnitude
110-113 F4.2 mag e_W2mag [0.01/0.27]? W2mag uncertainty
115-119 F5.2 mag W3mag [5.12/10]? WISE W3-band (12um) magnitude
121-124 F4.2 mag e_W3mag [0.02/0.1]? W3mag uncertainty
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Set Sample (G1)
9- 10 I2 --- Seq [1/96] Identification number
12- 13 I2 h RAh Hour of right ascension (J2000)
15- 16 I2 min RAm Minute of right ascension (J2000)
18- 23 F6.3 s RAs Second of right ascension (J2000)
25 A1 --- DE- Sign of declination (J2000)
26- 27 I2 deg DEd Degree of declination (J2000)
29- 30 I2 arcmin DEm Arcminute of declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of declination (J2000)
38- 41 F4.2 Msun M* [0.1/4.6] Stellar mass
43- 46 F4.2 Msun e_M* [0.1/2.3] Mass uncertainty
48- 51 F4.2 [yr] logt* [3.3/6.7] Stellar age
53- 56 F4.2 [yr] e_logt* [0.07/1.3] logt* uncertainty
58- 61 F4.2 [K] logT [3.4/4.2] log of Temperature
63- 66 F4.2 [K] e_logT [0.01/0.3] logT uncertainty
68- 73 F6.2 [Msun/yr] dM/dt [-12.9/-6.3] Disk accretion rate
75- 78 F4.2 [Msun/yr] e_dM/dt [0.5/3] dM/dt uncertainty
80- 84 F5.2 mag Av [1.3/16.3] Foreground visual extinction (AV)
86- 89 F4.2 mag e_Av [0.2/8] Av uncertainty
91- 94 F4.2 --- chi2 [0.03/8.3] χ2min per data point of
the best fit
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Global note:
Note (G1): Sample as follows:
L10 = LDN1657A-2 and 3 from Linz et al. (2010A&A...518L.123L 2010A&A...518L.123L)
H-K>0.6 = YSOs with H-K>0.6mag
ClassII = Class II-type sources
Ha = Hα emission line sources
Haout = Hα emission line sources outside NIR FoV
(NIR magnitudes taken from 2MASS catalog).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 10-Jul-2014