SN 1993J: A type IIb supernova

S. E. Woosley, Ronald G. Eastman, Thomas A. Weaver, Philip A Pinto

Research output: Contribution to journalArticle

192 Scopus citations

Abstract

The evolution of the bright Type II supernova discovered last year in M81, SN 1993J, is consistent with that expected for the explosion of a star which on the main sequence had a mass of 13-16 M but which, owing to mass exchange with a binary companion (a initially ∼3-5 AU, depending upon the actual presupernova radius and the masses of the two stars) lost almost all of its hydrogen-rich envelope during late helium burning. At the time of explosion, the helium core mass was 4.0 ± 0.5 M and the hydrogen envelope, 0.20 ± 0.05 M⊙. The envelope was helium and nitrogen-rich (carbon-deficient) and the radius of the star, 4 ± 1 × 1013 cm. The luminosity of the presupernova star was 3 ± 1 × 1038 ergs s-1, with the companion star contributing an additional ∼ 1038 ergs s-1. The star may have been a pulsating variable at the time of the explosion. For an explosion energy near 1051 ergs (KE at infinity) and an assumed distance of 3.3 Mpc, a mass of 56Ni in the range 0.07 ± 0.01 M was produced and ejected. This prescription gives a light curve which compares favorably with the bolometric observations. Color photometry is more restrictive and requires a model in which the hydrogen-envelope mass is low and the mixing of hydrogen inward has been small, but in which appreciable 56Ni has been mixed outward into the helium and heavy-element core. It is possible to obtain good agreement with B and V light curves during the first 50 days, but later photometry, especially in bands other than B and V, will require a non-LTE spectral calculation for comparison. Based upon our model, we predict a flux of ∼10-5 (3.3 Mpc/D)2 photons cm-2 s-1 in the 847 kcV line of 56Co at peak during 1993 August. It may be easier to detect the Comptonized continuum which peaks at a few times 10-4 photons s-1 cm-2 MeV-1 at 40 keV a few months after the explosion (though neither of these signals were, or should have been, detected by the Compton Gamma-Ray Observatory). The presupernova star was filling its Roche lobe at the time of the explosion and thus its envelope was highly deformed (about 3:2). The companion star is presently embedded in the supernova, but should become visible at age 3 yr (perhaps earlier in the ultraviolet) when the supernova has faded below 1038 ergs s-1. Indeed, if "kicks" have not played an important role, it is still bound to the neutron star.

Original languageEnglish (US)
Pages (from-to)300-318
Number of pages19
JournalAstrophysical Journal
Volume429
Issue number1
Publication statusPublished - Jul 1 1994

    Fingerprint

Keywords

  • Galaxies: individual (M81)
  • Supernovae: individual (SN 1993J)

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Woosley, S. E., Eastman, R. G., Weaver, T. A., & Pinto, P. A. (1994). SN 1993J: A type IIb supernova. Astrophysical Journal, 429(1), 300-318.