In a paper published today in Science, astronomers show that Type 1a supernovae, the kind used to measure the expansion rate of the universe, can be caused in more than one way, something not previously expected.


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The uncertainty of science: In a paper published today in Science, astronomers show that Type 1a supernovae, the kind used to measure the expansion rate of the universe, can be caused in more than one way, something not previously expected.

Andy Howell, second author on the study, said: “It is a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars. It is like discovering that some humans evolved from ape-like ancestors, and others came from giraffes. How could they look so similar if they had such different origins?” Howell is the leader of the supernova group at LCOGT, and is an adjunct faculty member in physics at UCSB.

Recently, some studies have found that Type Ia supernovae are not perfect standard candles –– their brightness depends on the type of galaxy in which they were discovered. The reason is a mystery, but the finding that some Type Ia supernovae come from different progenitors would seem to suggest that the supernova’s ultimate brightness may be affected by whether or not it comes from a nova or a white dwarf merger.

“We don’t think this calls the presence of dark energy into question,” said Dilday. “But it does show that if we want to make progress understanding it, we need to understand supernovae better.”

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