VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust

Details VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust

2009-08-07

arxiv.org/abs/0908.0942v2

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

Accepted for publication in Astronomy and Astrophysics. 16 pages, 16 figures

Scientific paper

AIMS: The main goal of this work is to study possible signs of asymmetry in the bright optical transient in NGC300, with the aim of getting independent information on the explosion mechanism, the progenitor star and its circumstellar environment. METHODS: Using VLT-FORS1 we have obtained low-resolution optical linear spectropolarimetry of NGC300 OT2008-1 on two epochs, 48 and 55 days after the discovery, covering the spectral range 3600--9330A. RESULTS: The data show a continuum polarization at a very significant level. At least two separate components are identified. The first is characterized by a strong wavelength dependency and a constant position angle (68.6+/-0.3 degrees), which is parallel to the local spiral arm of the host galaxy. The second shows a completely different position angle (151.3+/-0.4) and displays a mild but statistically significant evolution between the two epochs. While the former is identified as arising in the interstellar dust associated with NGC300, the latter is most likely due to continuum polarization by dust scattering in the circumstellar environment. No line depolarization is detected in correspondence of the most intense emission lines, disfavoring electron scattering as the source of intrinsic polarization. This implies a very small deviation from symmetry in the continuum-forming region. Given the observed level of intrinsic polarization, the transient must be surrounded by a significant amount of dust (>4x10^-5 Msun), asymmetrically distributed within a few thousand AU. This most likely implies that one or more asymmetric outflow episodes took place during the past history of the progenitor.

Affiliated with

Also associated with

No associations

Rating

VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust 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 VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and VLT Spectropolarimetry of the optical transient in NGC300. Evidence for asymmetry in the circumstellar dust will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-152489