A high sampling-density polarization study of the Southern Coalsack

Details A high sampling-density polarization study of the Southern Coalsack A high sampling-density polarization study of the Southern Coalsack

Jan 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005mnras.356.1088a&link_type=abstract

Monthly Notices of the Royal Astronomical Society, Volume 356, Issue 3, pp. 1088-1098.

Astronomy and Astrophysics

Astronomy

10

Polarization, Ism: Individual: Southern Coalsack, Ism: Magnetic Fields

Scientific paper

We present a densely sampled map of visual polarimetry of stars in the direction of the Southern Coalsack dark cloud. Our sample consists of new polarimetric observations of 225 stars drawn from the spectrophotometric survey of Seidensticker, and an additional 173 stars, covering the surrounding areas of the cloud, taken from the literature. Because all the target stars have at least spectroscopic parallaxes, we can reliably investigate the spatial origins of the polarization, in three dimensions. We decompose the polarization into three components, due to (i) the wall of the local hot bubble, (ii) the Coalsack cloud and (iii) material in the Carina spiral arm. The polarization due to the Coalsack varies, both in alignment efficiency (p/AV) and in the dispersion in polarization angle, across the cloud. Using a simplified radiative transfer treatment we show that the measured polarization in background gas is significantly affected by foreground polarization, and specifically that the analysis of the Coalsack polarization must take the effects of the local hot bubble wall into consideration. Correcting for this effect as well as for the internal line-of-sight averaging in the Coalsack, we find, based on a Chandrasekhar-Fermi analysis, a plane-of-the-sky magnetic field for the Coalsack cloud of = 93 +/- 23 μG. A systematic error, best described by a multiplicative factor between 0.5 and 1.5, additionally arises from radiative transfer effect uncertainties. We propose that this high value for the magnetic field in the cloud envelope is due to the fact that the Coalsack cloud is embedded in the hot interior of the Upper Centaurus-Lupus superbubble.

Affiliated with

Also associated with

No associations

Rating

A high sampling-density polarization study of the Southern Coalsack does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A high sampling-density polarization study of the Southern Coalsack, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A high sampling-density polarization study of the Southern Coalsack will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-809608