EARLY ULTRAVIOLET/OPTICAL EMISSION OF THE TYPE Ib SN 2008D

Journal Article · Sat Apr 20 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/767/2/143· OSTI ID:22126902

Bersten, Melina C.; Nomoto, Ken'ichi ^[1]; Tanaka, Masaomi ^[2]; Tominaga, Nozomu ^[3]

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1. Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)
2. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
3. Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan)

We propose an alternative explanation for the post-breakout emission of SN 2008D associated with the X-ray transient 080109. Observations of this object show a very small contrast of 0.35 dex between the light-curve minimum occurring soon after the breakout, and the main luminosity peak which is due to radioactive heating of the ejecta. Hydrodynamical models show that the cooling of a shocked Wolf-Rayet star leads to a much greater difference ({approx}> 0.9 dex). Our proposed scenario is that of a jet produced during the explosion which deposits {sup 56}Ni-rich material in the outer layers of the ejecta. The presence of high-velocity radioactive material allows us to reproduce the complete luminosity evolution of the object. Without outer {sup 56}Ni it could be possible to reproduce the early emission purely from cooling of the shocked envelope by assuming a larger progenitor than a Wolf-Rayet star, but that would require an initial density structure significantly different from what is predicted by stellar evolution models. Analytic models of the cooling phase have been proposed reproduce the early emission of SN 2008D with an extended progenitor. However, we found that the models are valid only until 1.5 days after the explosion where only two data of SN 2008D are available. We also discuss the possibility of the interaction of the ejecta with a binary companion, based on published analytic expressions. However, the binary separation required to fit the early emission should be {approx}< 3 R{sub Sun }, which is too small for a system containing two massive stars.

• OSTI ID: 22126902
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 767; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DENSITY
DEPOSITS
EMISSION
EXPLOSIONS
HYDRODYNAMICS
INTERACTIONS
LAYERS
LUMINOSITY
NICKEL 56
PEAKS
RADIOACTIVE MATERIALS
STAR EVOLUTION
SUPERNOVAE
TRANSIENTS
ULTRAVIOLET RADIATION
WOLF-RAYET STARS
X RADIATION