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SALT LAKE CITY — A weak supernova may have left behind what astronomers are calling a “zombie” star.
The zombie star is the surviving portion of a dying white dwarf star that exploded in an unusually weak supernova, according to a study published Thursday in the journal “Nature.” Researchers said white dwarf stars are usually completely destroyed in the explosion.
“I was very surprised to see anything at the location of the supernova,” lead author Curtis McCully said in a statement. “We expected the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us.”
Astronomers observed a blue companion star in old Hubble images “feeding energy” to the white dwarf. The energy intake sparked a nuclear reaction that resulted in a Type Iax supernova, which they named SN 2012Z.
McCully said he noticed the possible zombie star while sharpening Hubble images. A strange object near the supernova caught his attention and after further research “the team concluded they were seeing the light of a star that had lost its outer hydrogen envelope, revealing its helium core,” according to a statement from NASA.
I was very surprised to see anything at the location of the supernova.
–lead author Curtis McCully
The supernova SN 2012Z is located in a galaxy that is located 110 million light-years away called NGC 1309. McCully’s team plans to continue to observe the supernova and potential zombie star to confirm their findings.
Researchers are still working to understand Type Ia supernovae, which are less common.
“Astronomers have been searching for decades for the star systems that produce Type Ia supernova explosions,” said scientist Saurabh Jha in a statement. “Type Ia’s are important because they’re used to measure vast cosmic distances and the expansion of the universe.”
