SUB-CHANDRASEKHAR WHITE DWARF MERGERS AS THE PROGENITORS OF TYPE Ia SUPERNOVAE

Journal Article · Wed Oct 20 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/722/2/L157· OSTI ID:21452744

Van Kerkwijk, Marten H ^[1]; Chang, Philip ^[2]; Justham, Stephen ^[3]

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1. Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, ON M5S 3H4 (Canada)
2. Canadian Institute for Theoretical Astrophysics, 60 Saint George Street, Toronto, ON M5S 3H8 (Canada)
3. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

Type Ia supernovae (SNe Ia) are generally thought to be due to the thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs) with masses near the Chandrasekhar mass. This scenario, however, has two long-standing problems. First, the explosions do not naturally produce the correct mix of elements, but have to be finely tuned to proceed from subsonic deflagration to supersonic detonation. Second, population models and observations give formation rates of near-Chandrasekhar WDs that are far too small. Here, we suggest that SNe Ia instead result from mergers of roughly equal-mass CO WDs, including those that produce sub-Chandrasekhar mass remnants. Numerical studies of such mergers have shown that the remnants consist of rapidly rotating cores that contain most of the mass and are hottest in the center, surrounded by dense, small disks. We argue that the disks accrete quickly, and that the resulting compressional heating likely leads to central carbon ignition. This ignition occurs at densities for which pure detonations lead to events similar to SNe Ia. With this merger scenario, we can understand the type Ia rates and have plausible reasons for the observed range in luminosity and for the bias of more luminous supernovae toward younger populations. We speculate that explosions of WDs slowly brought to the Chandrasekhar limit-which should also occur-are responsible for some of the 'atypical' SNe Ia.

• OSTI ID: 21452744
• Journal Information: Astrophysical Journal Letters, Vol. 722, Issue 2; Other Information: DOI: 10.1088/2041-8205/722/2/L157; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON
LUMINOSITY
MASS
NUMERICAL ANALYSIS
OXYGEN
SUPERNOVAE
THERMONUCLEAR EXPLOSIONS
WHITE DWARF STARS
BINARY STARS
DWARF STARS
ELEMENTS
ERUPTIVE VARIABLE STARS
EXPLOSIONS
MATHEMATICS
NONMETALS
NUCLEAR EXPLOSIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
STARS
VARIABLE STARS