J/ApJ/708/758 Polarimetry of HH1-2 region (Kwon+, 2010)
Magnetic field structure of the HH 1-2 region: near-infrared polarimetry of
point-like sources.
Kwon J., Choi M., Pak S., Kandori R., Tamura M., Nagata T., Sato S.
<Astrophys. J., 708, 758-769 (2010)>
=2010ApJ...708..758K 2010ApJ...708..758K
ADC_Keywords: Polarization ; Photometry, infrared ; YSOs ; Molecular clouds
Keywords: infrared: stars - ISM: individual (HH 1-2) - ISM: structure -
polarization - stars: formation
Abstract:
The HH 1-2 region in the L1641 molecular cloud was observed in the
near-infrared (IR) J, H, and Ks bands, and imaging polarimetry was
performed. Seventy-six point-like sources were detected in all three
bands. The near-IR polarizations of these sources seem to be caused
mostly by the dichroic extinction. Using a color-color diagram,
reddened sources with little IR excess were selected to trace the
magnetic field structure of the molecular cloud. The mean polarization
position angle of these sources is about 111°, which is interpreted
as the projected direction of the magnetic field in the observed
region of the cloud. The distribution of the polarization angle has a
dispersion of about 11°, which is smaller than what was measured in
previous studies. This small dispersion gives a rough estimate of the
strength of the magnetic field to be about 130uG and suggests that
the global magnetic field in this region is quite regular and
straight. In contrast, the outflows driven by young stellar objects in
this region seem to have no preferred orientation. This discrepancy
suggests that the magnetic field in the L1641 molecular cloud does not
dictate the orientation of the protostars forming inside.
Description:
The observations toward the HH 1-2 region were carried out using the
SIRPOL imaging polarimeter on the Infrared Survey Facility (IRSF) 1.4m
telescope at the South African Astronomical Observatory. The
observations were made on the night of 2008 January 9.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 76 Photometry of point-like sources in the HH 1-2 field
table2.dat 69 76 Polarimetry of point-like sources in the HH 1-2 field
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/504/461 : YSOs in L1630N and L1641 (Fang+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Name Source name (<[KCP2010] NN> for Simbad)
4 I1 h RAh Hour of right ascension (J2000) (1)
6- 7 I2 min RAm Minute of right ascension (J2000)
9- 13 F5.2 s RAs Second of right ascension (J2000)
15 A1 --- DE- Sign of declination (J2000) (1)
16 I1 deg DEd Degree of declination (J2000) (1)
18- 19 I2 arcmin DEm Arcminute of declination (J2000)
21- 24 F4.1 arcsec DEs Arcsecond of declination (J2000)
26- 30 F5.2 mag Jmag J-band magnitude
32- 36 F5.2 mag Hmag H-band magnitude
38- 42 F5.2 mag Ksmag Ks-band magnitude
44- 45 A2 --- Group Group (A0, Ar or B) (2)
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Note (1): Positions are from the J-H-Ks image (Figure 1).
Note (2): Classification based on a color-color diagram (see Section 4.2).
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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 I2 --- Name Source name (<[KCP2010] NN> for Simbad)
4 A1 --- l_P(J) Limit flag on P(J) (3)
5- 9 F5.2 % P(J) J-band polarization
11- 15 F5.2 % e_P(J) ? P(J) uncertainty
17 A1 --- l_P(H) Limit flag on P(H) (3)
18- 22 F5.2 % P(H) H-band polarization
24- 27 F4.2 % e_P(H) ? P(H) uncertainty
29 A1 --- l_P(Ks) Limit flag on P(Ks) (3)
30- 34 F5.2 % P(Ks) Ks-band polarization
36- 39 F4.2 % e_P(Ks) ? P(Ks) uncertainty
41- 45 F5.1 deg PA(J) ? J-band polarization position angle
47- 49 F3.1 deg e_PA(J) ? PA(J) uncertainty
51- 55 F5.1 deg PA(H) ? H-band polarization position angle
57- 59 F3.1 deg e_PA(H) ? PA(H) uncertainty
61- 65 F5.1 deg PA(Ks) ? Ks-band polarization position angle
67- 69 F3.1 deg e_PA(Ks) ? PA(Ks) uncertainty
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Note (3): For sources with P/δP<3, the 3δP upper limits are listed.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 10-Feb-2012