An artist’s rendition of a supernova.
Four University of Victoria astrophysicists were contributors to a paper in a recent edition of Nature that is causing quite a stir in astronomical circles.
The paper describes how a stellar explosion known as a type 1a supernova is more than two times brighter than accepted theory says it should be. This is significant because these supernovae are used as cosmological beacons—they’re very bright and can be seen at large distances—to measure the expansion of the universe.
“These supernovae are the lynchpin in the measurement of dark energy in the universe—arguably the most exciting development in cosmology in the last century,” says UVic astrophysicist Dr. Chris Pritchet, one of the paper’s authors.
The problem is, no one is sure how type 1a supernovae are born. Two popular theories involve “white dwarf stars”—the corpses of dead stars that have a mass roughly one million times higher than the density of water. Both theories rely on the assumption that a white dwarf star can never exceed the so-called “Chandrasekhar mass”—roughly 1.4 times the mass of the sun.
But now—using software designed by the UVic team—an international group of astronomers has discovered a type 1a supernova that reached a whopping 2.2 solar masses before it exploded.
“There are several possible explanations,” says Pritchet, “but the bottom line is that this observation poses problems for conventional theories. This is a really big deal in the supernova community—it’s a first clue to the nature of stars that turn into these types of supernovae.”
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