The properties of the ‘standard’ Type Ic supernova 1994I from spectral models

• Published in: Monthly notices of the Royal Astronomical Society Vol. 369; no. 4; pp. 1939 - 1948
• Main Authors: Sauer, D. N., Mazzali, P. A., Deng, J., Valenti, S., Nomoto, K., Filippenko, A. V.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 11-07-2006; Blackwell Science; Oxford University Press
• Subjects: Astronomy; Astrophysics; Earth, ocean, space; Exact sciences and technology; Gamma rays; gamma-rays: bursts; line: formation; line: identification; Monte Carlo simulation; radiative transfer; Spectrum analysis; Supernovae; supernovae: general; supernovae: individual: SN 1994I; line: formation; line: identification; gamma-rays: bursts; supernovae: individual: SN 1994I; supernovae: general; radiative transfer; Mixing; Cosmic gamma sources; supernovae: individual: SN 19941; Line identification; Light curves; Line formation; Spectral model; Abundance; Gamma ray burst; supemovae: general; Type I supernova; Radiative transfer
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2006.10438.x

The properties of the Type Ic supernova SN 1994I are reinvestigated. This object is often referred to as a ‘standard SN Ic’ although it exhibited an extremely fast light curve and unusually blue early-time spectra. In addition, the observations were affected by significant dust extinction. A series of spectral models is computed based on the explosion model CO21 using a Monte Carlo transport spectral synthesis code. Overall the density structure and abundances of the explosion model are able to reproduce the photospheric spectra well. Reddening is estimated to be E(B−V) = 0.30 mag, a lower value than previously proposed. A model of the nebular spectrum of SN 1994I points towards a slightly larger ejecta mass than that of CO21. The photospheric spectra show a large abundance of iron-group elements at early epochs, indicating that mixing within the ejecta must have been significant. We present an improved light curve model which also requires the presence of 56Ni in the outer layers of the ejecta.