SPECTROPOLARIMETRY OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc: NEARLY SPHERICAL EXPLOSION OF SUPER-CHANDRASEKHAR MASS WHITE DWARF
- Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa (Japan)
- Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima (Japan)
- Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
- Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo (Japan)
- Max-Planck Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany)
- Istituto Naz. di Astrofisica-Oss. Astron., Via Tiepolo, 11, 34131 Trieste (Italy)
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 {sup 56}Ni-rich layers ({approx_gt}1.2 M{sub sun}). 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.
- OSTI ID:
- 21448852
- Journal Information:
- Astrophysical Journal, Vol. 714, Issue 2; Other Information: DOI: 10.1088/0004-637X/714/2/1209; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
AXIAL SYMMETRY
EXPLOSIONS
GEOMETRY
MASS
NICKEL 56
POLARIZATION
SUPERNOVAE
WHITE DWARF STARS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BINARY STARS
DAYS LIVING RADIOISOTOPES
DWARF STARS
ELECTRON CAPTURE RADIOISOTOPES
ERUPTIVE VARIABLE STARS
EVEN-EVEN NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
MATHEMATICS
NICKEL ISOTOPES
NUCLEI
RADIOISOTOPES
STARS
SYMMETRY
VARIABLE STARS