Solar System Chatter

Supernova Smash

Courtesy of Dan Kasen
Courtesy of Dan Kasen
Type 1a supernovas are important in the study of the universe. They start as white dwarfs—dead stars that no longer have fusion reactions—that accumulate material from a companion star, until they reach a certain mass limit and re-ignite in a supernova explosion. Their predictable brightness means cosmologists can use them as “standard candles.” But mysteries abound about what makes up the companion star, which is usually destroyed by the explosion. Astronomers at the intermediate Palomar Transient Factory (iPTF) have some new answers, after using their “rapid response” telescope system, including NASA’s Swift gamma-ray observatory, to watch a supernova just as it ignited and smashed into its companion star, giving off a signature ultraviolet light indicating that the companion was another white dwarf that merged with the star that exploded. However, another supernova’s companion was recently found on pre-explosion Hubble images—that star was a red giant. As one astronomer involved in the study, Andrew Howell, said in the announcement, “No wonder we’ve been so confused for decades. Apparently you can blow up stars in two different ways and still get nearly identical explosions.”

Heather Goss is the Departments Editor at Air & Space.

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supernova, Swift