SUB-CHANDRASEKHAR MASS MODELS FOR SUPERNOVAE

Journal Article · Fri Jun 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/734/1/38· OSTI ID:21576684

Woosley, S E ^[1]; Kasen, Daniel ^[2]

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1. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2. Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

For carbon-oxygen white dwarfs accreting hydrogen or helium at rates in the range {approx}(1-10) x 10{sup -8} M{sub sun} yr{sup -1}, a variety of explosive outcomes is possible well before the star reaches the Chandrasekhar mass. These outcomes are surveyed for a range of white dwarf masses (0.7-1.1 M{sub sun}), accretion rates ((1-7) x 10{sup -8} M{sub sun} yr{sup -1}), and initial white dwarf temperatures (0.01 and 1 L{sub sun}). The results are particularly sensitive to the convection that goes on during the last few minutes before the explosion. Unless this convection maintains a shallow temperature gradient and unless the density is sufficiently high, the accreted helium does not detonate. Below a critical helium ignition density, which we estimate to be (5-10) x 10{sup 5} g cm{sup -3}, either helium novae or helium deflagrations result. The hydrodynamics, nucleosynthesis, light curves, and spectra of a representative sample of detonating and deflagrating models are explored. Some can be quite faint indeed, powered at peak for a few days by the decay of {sup 48}Cr and {sup 48}V. Only the hottest, most massive white dwarfs considered with the smallest helium layers, show reasonable agreement with the light curves and spectra of common Type Ia supernovae (SNe Ia). For the other models, especially those involving lighter white dwarfs, the helium shell mass exceeds 0.05 M{sub sun} and the mass of the {sup 56}Ni that is synthesized exceeds 0.01 M{sub sun}. These explosions do not look like ordinary SNe Ia or any other frequently observed transient.

• OSTI ID: 21576684
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 734; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
DWARF STARS
ELEMENTS
ERUPTIVE VARIABLE STARS
FLUID MECHANICS
FLUIDS
GASES
HELIUM
HYDRODYNAMICS
MASS
MECHANICS
NONMETALS
NUCLEOSYNTHESIS
RARE GASES
SHOCK WAVES
SPECTRA
STARS
SUPERNOVAE
SYNTHESIS
VARIABLE STARS
WHITE DWARF STARS