TY - JOUR
T1 - Spectropolarimetry of extremely luminous type Ia supernova 2009dc
T2 - Nearly spherical explosion of super-chandrasekhar mass white dwarf
AU - Tanaka, Masaomi
AU - Kawabata, Koji S.
AU - Yamanaka, Masayuki
AU - Maeda, Keiichi
AU - Hattori, Takashi
AU - Aoki, Kentaro
AU - Nomoto, Ken'Ichi
AU - Iye, Masanori
AU - Sasaki, Toshiyuki
AU - Mazzali, Paolo A.
AU - Pian, Elena
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2010
Y1 - 2010
N2 - 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 TypeIaSNe. This may suggest that there are thick enough, clumpy Si-rich layers above the thick 56Ni-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.
AB - 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 TypeIaSNe. This may suggest that there are thick enough, clumpy Si-rich layers above the thick 56Ni-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.
KW - Polarization
KW - Supernovae: general
KW - Supernovae: individual (SN 2009dc, SNe 2003fg, 2006gz, 1991T)
KW - White dwarfs
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U2 - 10.1088/0004-637X/714/2/1209
DO - 10.1088/0004-637X/714/2/1209
M3 - Article
AN - SCOPUS:77951678776
VL - 714
SP - 1209
EP - 1216
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
ER -