J/ApJ/743/54 Polarization around star-forming regions (Targon+, 2011)
Correlating the interstellar magnetic field with protostellar jets and
its sources.
Targon C.G., Rodrigues C.V., Cerqueira A.H., Hickel G.R.
<Astrophys. J., 743, 54 (2011)>
=2011ApJ...743...54T 2011ApJ...743...54T
ADC_Keywords: YSOs ; Magnetic fields ; Polarization
Keywords: Herbig-Haro objects - ISM: jets and outflows - ISM: magnetic fields -
stars: formation - techniques: polarimetric
Abstract:
This paper combines new CCD polarimetric data with previous
information about protostellar objects in a search for correlations
involving the interstellar magnetic field (ISMF). Specifically, we
carried out an optical polarimetric study of a sample of 28 fields of
10'x10' located in the neighborhood of protostellar jets and randomly
spread over the Galaxy. The polarimetry of a large number of field
stars is used to estimate both the average and dispersion of the ISMF
direction in each region. The results of the applied statistical tests
are as follows. Concerning the alignment between the jet direction and
the ISMF, the whole sample does not show alignment. There is, however,
a statistically significant alignment for objects of Classes 0 and I.
Regarding the ISMF dispersion, our sample presents values slightly
larger for regions containing T Tauri objects than for those harboring
younger protostars. Moreover, the ISMF dispersion in regions
containing high-mass objects tends to be larger than in those
including only low-mass protostars. In our sample, the mean
interstellar polarization as a function of the average interstellar
extinction in a region reaches a maximum value around 3% for A(V)=5,
after which it decreases. Our data also show a clear correlation of
the mean value of the interstellar polarization with the dispersion of
the ISMF: the larger the dispersion, the smaller the polarization.
Based on a comparison of our and previous results, we suggest that the
dispersion in regions forming stars is larger than in quiescent
regions.
Description:
This catalog presents the polarimetry of field stars in 28 regions in
the direction of Herbig-Haro objects.
The table includes the position and R band polarization of many
objects in each field. The field number is presented in the first
column. The identification number of a given object in each field is
presented in the second column.
The observations were carried out in 1998 December 18, between 2005
February 11 and 17, and on 2007 May 7, with the 0.60m Boller &
Chivens telescope at the Observatorio do Pico dos Dias, Brazil,
operated by the Laboratorio Nacional de Astrofisica, Brazil.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 28 Star-forming region or cloud in the direction
of each field
table4.dat 49 4872 Polarimetry of field stars in each field
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Field Field number
4- 76 A73 --- Region Region designation
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Field Field number
3 A1 --- m_Field [AB] Multiplicity index on Field
5- 7 I3 --- ID Identification of the object in the field
9- 10 I2 h RAh Hour of Right Ascension (B1950)
12- 13 I2 min RAd Minute of Right Ascension (B1950)
15- 19 F5.2 s RAs Second of Right Ascension (B1950)
21 A1 --- DE- Sign of the Declination (B1950)
22- 23 I2 deg DEd Degree of Declination (B1950)
25- 26 I2 arcmin DEm Arcminute of Declination (B1950)
28- 32 F5.2 arcsec DEs Arcsecond of Declination (B1950)
34- 38 F5.2 % P Linear polarization
40- 43 F4.2 % e_P Error in P
45- 49 F5.1 deg PA Position angle of the polarization
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Acknowledgements:
Claudia V. Rodrigues, claudiavilega(at)gmail.com
(End) Claudia V. Rodrigues [INPE], Patricia Vannier [CDS] 24-Feb-2012