Issue |
A&A
Volume 421, Number 1, July I 2004
|
|
---|---|---|
Page(s) | 195 - 202 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20034481 | |
Published online | 11 June 2004 |
First polarimetry results of two candidate high-mass protostellar objects
1
Centre for Astrophysics Research, Science and Technology Research Centre, University of Hertfordshire, College Lane, Hatfield, HERTS, AL10 9AB, UK
2
Joint Astronomy Centre, 660 N. A`ohōkū Place, Hilo, HI 96720, USA
Corresponding author: R. L. Curran, rcurran@star.herts.ac.uk
Received:
9
October
2003
Accepted:
23
March
2004
We present m imaging polarimetry of two high-mass star forming
regions – W48 and S152. Within these regions we have identified two
candidate high-mass protostellar objects – W48W and S152SE. The
submillimetre continuum emission from the candidate HMPOs is bright in
comparison to the nearby
regions. W48W is a cold dense source,
with no radio or mid-infrared emission. S152SE has an IRAS source IRAS
22566 +5828 in the Southwestern part of the region, which appears in
the mid-infrared
m emission, but there is no radio
emission. The
m data shows another core within the region, in
the Northeast. The polarimetry is ordered and the degree of
polarisation is high over the candidate HMPOs –
for W48W
and
for S152SE. Polarimetry results of this nature
indicate a strong, ordered magnetic field threading the candidate
HMPOs. The magnetic field direction in both S152SE and W48W is
perpendicular to the direction of elongation of the cloud which would
imply collapse along the field lines. Estimates of the magnetic field
strength are derived using the Chandrasekhar & Fermi method. We
calculate plane of the sky field strengths of ~0.7 mG for W48W
and ~0.2 mG for S152SE. We discuss the drawbacks of using the
Chandrasekhar & Fermi method with a large beam size. Mass-to-flux
ratios have been calculated and both clouds are found to be roughly
critical.
Key words: ISM: magnetic fields / ISM: individual objects: W48, S152 / stars: formation / techniques: polarimetric / submillimeter
© ESO, 2004
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