Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2009-09-30
Astron.Astrophys.508:229-246,2009
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
28 pages, 39 figures, accepted for publication in Astronomy and Astrophysics
Scientific paper
10.1051/0004-6361/200810651
Using VLT-FORS1 we performed optical spectropolarimetric observations of the Type Ia SN2006X on 7 pre-maximum epochs (day -10 to day -1) and one post-maximum epoch (+39 days). The SN shows strong continuum interstellar polarization reaching about 8% at 4000A, characterized by a wavelength dependency that is substantially different from that of the Milky-Way dust mixture. Several SN features, like SiII 6355A and the CaII IR triplet, present a marked evolution. The CaII near-IR triplet shows a pronounced polarization (~1.4%) already on day -10 in correspondence with a strong high-velocity feature (HVF). The SiII polarization peaks on day -6 at about 1.1% and decreases to 0.8% on day -1. By day +39 no polarization signal is detected for the SiII line, while the CaII IR triplet shows a marked re-polarization at the level of 1.2%. As in the case of another strongly polarized SN (2004dt), no polarization was detected across the OI 7774A absorption. The fast-expanding SN2006X lies on the upper edge of the relation between peak polarization and decline rate, and it confirms previous speculations about a correlation between degree of polarization, expansion velocity, and HVF strength. The polarization of CaII detected in our last epoch, the most advanced ever obtained for a Type Ia SN, coincides in velocity with the outer boundary of the Ca synthesized during the explosion (15,000-17,000 km/s) in delayed-detonation models. This suggests a large scale chemical inhomogeneity as produced by off-center detonations, a rather small amount of mixing, or a combination of both effects. In contrast, the absence of polarization at the inner edge of the Ca-rich layer (8000-10,000 km/s) implies a substantial amount of mixing in these deeper regions.
Baade Dietrich
Hoeflich Peter
Maund Justyn R.
Patat Ferdinando
Wang Lanjuan
No associations
LandOfFree
VLT Spectropolarimetry of the fast expanding Type Ia SN2006X 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 fast expanding Type Ia SN2006X, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and VLT Spectropolarimetry of the fast expanding Type Ia SN2006X will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-589836