J/ApJ/751/138 VRIJHK photometry of IRAS 09149-4743 region (Santos+, 2012)
A young stellar cluster within the RCW41 H II region: deep NIR photometry and
Optical/NIR polarimetry.
Santos F.P., Roman-Lopes A., Franco G.A.P.
<Astrophys. J., 751, 138 (2012)>
=2012ApJ...751..138S 2012ApJ...751..138S
ADC_Keywords: Photometry, infrared ; Polarization ; H II regions ; YSOs
Keywords: ISM: clouds - ISM: magnetic fields - techniques: polarimetric -
open clusters and associations: individual: RCW41 -
stars: formation - techniques: photometric
Abstract:
The RCW41 star-forming region is embedded within the Vela Molecular
Ridge, hosting a massive stellar cluster surrounded by a conspicuous
HII region. Understanding the role of interstellar magnetic fields
and studying the newborn stellar population is crucial to building a
consistent picture of the physical processes acting on this kind of
environment. We carried out a detailed study of the interstellar
polarization toward RCW41 with data from an optical and near-infrared
polarimetric survey. Additionally, deep near-infrared images from the
3.5 meter New Technology Telescope were used to study the photometric
properties of the embedded young stellar cluster, revealing several
YSO candidates. By using a set of pre-main-sequence isochrones, a mean
cluster age in the range 2.5-5.0 million years was determined, and
evidence of sequential star formation was revealed. An abrupt decrease
in R-band polarization degree was noticed toward the central ionized
area, probably due to low grain alignment efficiency caused by the
turbulent environment and/or the weak intensity of magnetic fields.
The distortion of magnetic field lines exhibits dual behavior, with
the mean orientation outside the area approximately following the
borders of the star-forming region and directed radially toward the
cluster inside the ionized area, in agreement with simulations of
expanding H II regions. The spectral dependence of polarization
allowed a meaningful determination of the total-to-selective
extinction ratio by fittings of the Serkowski relation. Furthermore, a
large rotation of polarization angle as a function of wavelength was
detected toward several embedded stars.
Description:
The raw imaging data for the IRAS 09149-4743 region were retrieved
from the ESO archive. The observations comprise two separate programs
with the following identifiers: 073.D-0102 (PI: Dr. Sergio Ortolani)
and 080.D-0470 (PI: Dr. Ben Davies). The observing missions were
conducted during the nights of 2004 May 5 and 2008 February 10 using
the SofI (Son of Isaac) NIR camera mounted on the 3.58 meter New
Technology Telescope (NTT) from La Silla/Chile.
The 2004 survey denoted "Dataset A," corresponds to J, H, and Ks band
observations using a 0.144"/pix plate scale, which allows a 2.1'x2.1'
field of view. The FWHM values of point-like sources at this
observational run are of ∼1".
The observational data from the 2008 survey (which we hereafter denote
"Dataset B") were obtained using the H and Ks bands, with a plate
scale of 0.288"/pix, allowing a field of view of about 4.9'x4.9'
(extended to 7.4'x7.4' (see Section 2)). Atmospheric conditions during
this observational run allowed mean FWHM values of ∼0.7".
The optical and NIR polarimetric data used in this work have been
separately obtained with different telescopes and instrumental
configurations. The optical data, in V, R, and I Johnson-Cousins'
filters, were collected using the 0.9m telescope of the CTIO (Cerro
Tololo, Chile, operated by the National Optical Astronomy
Observatory-NOAO) observatory, during 2010 February and April and 2011
March. The NIR data, in the H band, were obtained using the 1.6m
telescope of the OPD (Observatorio Pico do Dias, Brazil, operated by
Laboratorio Nacional de Astrofisica-LNA/MCT) during 2011 April.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 530 Near-IR photometric data of RCW41 from Dataset A
table2.dat 61 2608 Near-IR photometric data of RCW41 from Dataset B
table3.dat 47 1823 The V, R, I and H polarimetric data set
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/707/1836 : BLAST survey in Vela-D (Olmi+, 2009)
J/A+A/461/949 : JHK photometry around IRAS 09149-4743 (Ortiz+, 2007)
J/A+A/399/147 : JHK photometry of C-cloud IRAS sources (Massi+, 2003)
J/A+A/400/533 : New IR star clusters in southern Milky Way (Dutra+, 2003)
J/A+AS/136/471 : JHK photometry of D-cloud IRAS sources (Massi+, 1999)
J/A+AS/115/285 : Catalogue of massive young stellar objects (Chan+, 1996)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 h RAh [9] Hour of Right Ascension (J2000)
3- 4 I2 min RAm [16/17] Minute of Right Ascension (J2000)
6- 10 F5.2 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- [-] Sign of the Declination (J2000)
13- 14 I2 deg DEd [47/48] Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 22 F4.1 arcsec DEs Arcsecond of Declination (J2000)
24- 29 F6.3 mag Jmag [9.7/21.8]? NTT/SofI J band magnitude
(only for table 1) (1)
31- 35 F5.3 mag e_Jmag [0.02/0.3]? Uncertainty in Jmag
(only for table 1) (1)
37- 42 F6.3 mag Hmag [8.9/21]? NTT/SofI H band magnitude (1)
44- 48 F5.3 mag e_Hmag [0.01/0.6]? Uncertainty in Hmag(1)
50- 55 F6.3 mag Ksmag [8.6/20] NTT/SofI KS band magnitude
57- 61 F5.3 mag e_Ksmag [0.01/0.6] Uncertainty in Ksmag
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Note (1): Blank values indicate undetected stars (in each specific band),
or saturated objects.
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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 I1 h RAh [9] Hour of Right Ascension (J2000)
3- 4 I2 min RAm [15/18] Minute of Right Ascension (J2000)
6- 10 F5.2 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- [-] Sign of the Declination (J2000)
13- 14 I2 deg DEd [47/48] Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 22 F4.1 arcsec DEs Arcsecond of Declination (J2000)
24 A1 --- Band [HIRV] Observed spectral band (V, R, I or H)
26- 30 F5.2 % Pol [0.01/16]? Polarization (1)
32- 35 F4.2 % e_Pol [0.02/7]? Uncertainty in Pol (1)
37- 41 F5.1 deg PA [0/180]? Position angle of polarization (1)
43- 47 F5.1 deg e_PA [0.3/271]? Uncertainty in PA (1)
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Note (1): Blanks indicate objects that were detected in the indicated band,
but presents bad polarization values, as defined in Section 2.2.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-Jan-2014