Nebular phase observations of the type Ib supernova 2008D/X-Ray transient 080109: Side-viewed bipolar explosion

Masaomi Tanaka, Masayuki Yamanaka, Keiichi Maeda, Koji S. Kawabata, Takashi Hattori, Takeo Minezaki, Stefano Valenti, Massimo Della Valle, D. K. Sahu, G. C. Anupama, Nozomu Tominaga, Ken'Ichi Nomoto, Paolo A. Mazzali, Elena Pian

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

We present optical spectroscopic and photometric observations of supernova (SN) 2008D, associated with the luminous X-ray transient 080109, at >300 days after the explosion (nebular phases). We also give flux measurements of emission lines from the H II region at the site of the SN, and estimates of the local metallicity. The brightness of the SN at nebular phases is consistent with the prediction of the explosion models with an ejected 56Ni mass of 0.07M, which explains the light curve at early phases. The [O I] line in the nebular spectrum shows a double-peaked profile while the [Ca II] line does not. The double-peaked [O I] profile strongly indicates that SN 2008D is an aspherical explosion. The profile can be explained by a torus-like distribution of oxygen viewed from near the plane of the torus. We suggest that SN 2008D is a side-viewed, bipolar explosion with a viewing angle of >50° from the polar direction.

Original languageEnglish
Pages (from-to)1680-1685
Number of pages6
JournalAstrophysical Journal
Volume700
Issue number2
DOIs
Publication statusPublished - 2009 Jan 1
Externally publishedYes

Keywords

  • Line: profiles
  • Nuclear reactions, nucleosynthesis, abundances
  • Supernovae: general
  • Supernovae: individual (SN 2008D)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Tanaka, M., Yamanaka, M., Maeda, K., Kawabata, K. S., Hattori, T., Minezaki, T., Valenti, S., Valle, M. D., Sahu, D. K., Anupama, G. C., Tominaga, N., Nomoto, KI., Mazzali, P. A., & Pian, E. (2009). Nebular phase observations of the type Ib supernova 2008D/X-Ray transient 080109: Side-viewed bipolar explosion. Astrophysical Journal, 700(2), 1680-1685. https://doi.org/10.1088/0004-637X/700/2/1680