Early phase observations of extremely luminous type Ia supernova 2009dc

M. Yamanaka, K. S. Kawabata, K. Kinugasa, M. Tanaka, A. Imada, K. Maeda, K. Nomoto, A. Arai, S. Chiyonobu, Y. Fukazawa, O. Hashimoto, S. Honda, Y. Ikejiri, R. Itoh, Y. Kamata, N. Kawai, T. Komatsu, K. Konishi, D. Kuroda, H. MiyamotoS. Miyazaki, O. Nagae, H. Nakaya, T. Ohsugi, T. Omodaka, N. Sakai, M. Sasada, M. Suzuki, H. Taguchi, H. Takahashi, H. Tanaka, M. Uemura, T. Yamashita, K. Yanagisawa, M. Yoshida

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Abstract

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 Δm15(B) = 0.65 0.03, which is one of the slowest among SNe Ia. The peak V-band absolute magnitude is estimated to be MV = -19.90 0.15mag if no host extinction is assumed. It reaches MV = -20.19 0.19mag if we assume the host extinction of AV = 0.29mag. 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 0.3 M⊙ for the no host extinction case (and of 1.6 0.4 M⊙ for the host extinction of AV = 0.29mag). The C II λ6580 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 λ6355 is about 8000kms-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 etal. indicate that the explosion is nearly spherical. These observational facts suggest that SN 2009dc is a super-Chandrasekhar mass SN Ia.

Original languageEnglish
Pages (from-to)L118-L122
JournalAstrophysical Journal
Volume707
Issue number2 PART 2
DOIs
Publication statusPublished - 2009

Keywords

  • Supernovae: general
  • Supernovae: individual (SN 2009dc, SNe 2003fg, 2006gz)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Yamanaka, M., Kawabata, K. S., Kinugasa, K., Tanaka, M., Imada, A., Maeda, K., Nomoto, K., Arai, A., Chiyonobu, S., Fukazawa, Y., Hashimoto, O., Honda, S., Ikejiri, Y., Itoh, R., Kamata, Y., Kawai, N., Komatsu, T., Konishi, K., Kuroda, D., ... Yoshida, M. (2009). Early phase observations of extremely luminous type Ia supernova 2009dc. Astrophysical Journal, 707(2 PART 2), L118-L122. https://doi.org/10.1088/0004-637X/707/2/L118