SPECTROPOLARIMETRY OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc: NEARLY SPHERICAL EXPLOSION OF SUPER-CHANDRASEKHAR MASS WHITE DWARF

Journal Article · Mon May 10 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/2/1209· OSTI ID:21448852

Tanaka, Masaomi; Maeda, Keiichi; Nomoto, Ken'ichi ^[1]; Kawabata, Koji S; Yamanaka, Masayuki ^[2]; Hattori, Takashi; Aoki, Kentaro; Sasaki, Toshiyuki ^[3]; Iye, Masanori ^[4]; Mazzali, Paolo A ^[5]; Pian, Elena ^[6]

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1. Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa (Japan)
2. Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima (Japan)
3. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
4. Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo (Japan)
5. Max-Planck Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany)
6. 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, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AXIAL SYMMETRY
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BINARY STARS
DAYS LIVING RADIOISOTOPES
DWARF STARS
ELECTRON CAPTURE RADIOISOTOPES
ERUPTIVE VARIABLE STARS
EVEN-EVEN NUCLEI
EXPLOSIONS
GEOMETRY
INTERMEDIATE MASS NUCLEI
ISOTOPES
MASS
MATHEMATICS
NICKEL 56
NICKEL ISOTOPES
NUCLEI
POLARIZATION
RADIOISOTOPES
STARS
SUPERNOVAE
SYMMETRY
VARIABLE STARS
WHITE DWARF STARS