Failed explosions explain most peculiar supernovae
Baku, November 21 (AZERTAC). Supercomputer simulations have revealed that a type of oddly dim, exploding star is probably a class of duds—one that could nonetheless throw new light on the mysterious nature of dark energy.
Most of the thousands of exploding stars classified as type Ia supernovae look similar, which is why astrophysicists use them as accurate cosmic distance indicators. They have shown that the expansion of the universe is accelerating under the influence of an unknown force now called dark energy. Yet approximately 20 type Ia supernovae look peculiar.
“They`re all a little bit odd,” said George Jordan, a research scientist at the University of Chicago`s Flash Center for Computational Science. Comparing odd type Ia supernovae to normal ones may permit astrophysicists to more precisely define the nature of dark energy, he noted.
Jordan and three colleagues, including his chief collaborator on the project, Hagai Perets, assistant professor of physics at Technion - Israel Institute of Technology, have found that the peculiar type Ia supernovae are probably white dwarf stars that failed to detonate.
The triggering of a detonation wave is exactly what happens in normal type Ia supernovae, which incinerate white dwarfs, stars that have shrunk to Earth size after having burned most or all of their nuclear fuel. Most or all white dwarfs occur in binary systems, those that consist of two stars orbiting one another.
Peculiar type Ia supernovae are anywhere from 10 to 100 times fainter than normal ones, which are brighter and therefore more easily detected. Astrophysicists have estimated that they may account for approximately 15 percent of all type Ia supernovae.
Typical white dwarfs have compositions of carbon and oxygen, yet some of the simulated ones that failed to detonate displayed heavy elements such as calcium, titanium and iron. When the detonation fails to happen, much of the ejected mass falls back onto the surface of the white dwarf, where the heavy elements become synthesized.
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