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EARLY PHASE OBSERVATIONS OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc

Masahito YamanakaDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Koji S. KawabataHiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanK. KinugasaGunma Astronomical Observatory, Takayama, Gunma 377-0702, JapanMasayuki TanakaDepartment of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, JapanAkira ImadaOkayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi-shi, Okayama 719-0232, JapanKeiichi MaedaInstitute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, JapanK. NomotoInstitute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, JapanAkira AraiDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]S. ChiyonobuDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Y. FukazawaDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Osamu HashimotoGunma Astronomical Observatory, Takayama, Gunma 377-0702, JapanSatoshi HondaGunma Astronomical Observatory, Takayama, Gunma 377-0702, JapanY. IkejiriDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]R. ItohDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Y. KamataNational Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, JapanN. KawaiDepartment of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, JapanT. KomatsuDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]K. KonishiInstitute for Cosmic Ray Research, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8582, JapanD. KurodaOkayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi-shi, Okayama 719-0232, JapanHisakazu MiyamotoDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Satoshi MiyazakiNational Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, JapanOsamu NagaeDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Helder I. NakayaNational Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, JapanT. OhsugiHiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanT. OmodakaDepartment of Physics, Faculty of Science, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, JapanNobuyuki SakaiDepartment of Physics, Faculty of Science, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, JapanMahito SasadaDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]M. SuzukiHikaru TaguchiGunma Astronomical Observatory, Takayama, Gunma 377-0702, JapanH. TakahashiGunma Astronomical Observatory, Takayama, Gunma 377-0702, JapanHisashi TanakaDepartment of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan; [email protected]Makoto UemuraHiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, JapanTakuji YamashitaNational Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, JapanK. YanagisawaOkayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi-shi, Okayama 719-0232, JapanMakiko YoshidaOkayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi-shi, Okayama 719-0232, Japan

2009en

ABI

Annotatsiya

We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of the light curve is &Delta;m 15(B) = 0.65 &plusmn; 0.03, which is one of the slowest among SNe Ia. The peak V-band absolute magnitude is estimated to be MV = -19.90 &plusmn; 0.15 mag if no host extinction is assumed. It reaches MV = -20.19 &plusmn; 0.19 mag if we assume the host extinction of AV = 0.29 mag. SN 2009dc belongs to the most luminous class of SNe Ia, like SNe 2003fg and 2006gz. Our JHKs -band photometry shows that this SN is also one of the most luminous SNe Ia in near-infrared wavelengths. We estimate the ejected 56Ni mass of 1.2 &plusmn; 0.3 M sun for the no host extinction case (and of 1.6 &plusmn; 0.4 M sun for the host extinction of AV = 0.29 mag). The C II &lambda;6580 absorption line remains visible until a week after the maximum brightness, in contrast to its early disappearance in SN 2006gz. The line velocity of Si II &lambda;6355 is about 8000 km s-1 around the maximum, being considerably slower than that of SN 2006gz. The velocity of the C II line is similar to or slightly less than that of the Si II line around the maximum. The presence of the carbon line suggests that the thick unburned C+O layer remains after the explosion. Spectropolarimetric observations by Tanaka et al. indicate that the explosion is nearly spherical. These observational facts suggest that SN 2009dc is a super-Chandrasekhar mass SN Ia.

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DOI: 10.1088/0004-637x/707/2/l118

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