2009/08/31 by Masaomi Tanaka, Koji S. Kawabata, Masayuki Yamanaka +8
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #Interstellar medium #Line (geometry) #Mass distribution #Neutrino Physics Research #Pair-instability supernova #Polarization (electrochemistry) #Spectral line #Supernova #White dwarf #astro-ph.CO #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/714/2/1209
9 pages, 6 figures, The Astrophysical Journal, in press
arxiv created 2010/03/29 · openalex publication_date 2010/04/16 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present the first spectropolarimetric observations of a candidate of super-Chandrasekhar mass Type Ia supernova (SN): SN 2009dc. The observations were performed at 5.6 and 89.5 days after the B -band maximum. The data taken at the later epoch are used to determine the interstellar polarization. Continuum polarization is found to be small (<0.3%), indicating that the explosion is nearly spherically symmetric. This fact suggests that a very aspherical explosion is not a likely scenario for SN 2009dc. Polarization at the Si ii and Ca ii lines clearly shows a loop in the Q – U plane, indicating a non-axisymmetric, clumpy distribution of intermediate-mass elements. The degree of line polarization at the Si and Ca lines is moderate (0.5% ± 0.1% and 0.7% ± 0.1%, respectively), but it is higher than expected from the trend of other Type Ia SNe. This may suggest that there are thick enough, clumpy Si-rich layers above the thick 56 Ni-rich layers (≳1.2 M ☉ ). The observed spectropolarimetric properties, combined with the photometric and spectroscopic properties, suggest that the progenitor of SN 2009dc has a super-Chandrasekhar mass, and that the explosion geometry is globally spherically symmetric, with clumpy distribution of intermediate-mass elements.