Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with M~0.9 M_sun

Understand

Type Ia supernovae (SNe Ia) are thought to result from thermonuclear explosions of carbon-oxygen white dwarf stars.

• Existing models generally explain the observed properties, with the exception of the sub-luminous 1991-bg-like supernovae.
• It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but hitherto simulations have failed to produce an explosion.
• Here we report a simulation of the merger of two equal-mass white dwarfs that leads to an underluminous explosion, though at the expense of requiring a single common-envelope phase, and component masses of ~0.9 M_sun.