NASA finds zombie star in space

Even space has its Golimar Walking Dead.

 

Astronomers at the US National Aeronautics and Space Administration (NAS) have found traces of "zombie stars," following an unusually weak supernova explosion.

 

A so-called "zombie star" or "undead star" is one that has somehow survived obliteration following a white dwarf's explosive death.

 

“I was very surprised to see anything at the location of the supernova. 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,” said Curtis McCully, a graduate student at Rutgers and lead author of the team’s paper.

 

NASA said astronomers examining Hubble images taken years before the stellar explosion had identified a blue companion star feeding energy to a white dwarf, which can ignite a nuclear reaction.

 

This supernova, Type Iax, is less common than Type Ia.

 

30 mini-supernovas, 30 zombie stars?

 

So far, astronomers have identified more than 30 mini-supernovas that could leave behind a surviving white dwarf.

 

“Astronomers have been searching for decades for the star systems that produce Type Ia supernova explosions,” said Saurabh Jha of Rutgers University in New Jersey.

 

Jha said Type Ia's are used to measure cosmic distances and the expansion of the universe, but there are very few constraints on how any white dwarf explodes.

 

"This discovery shows us one way that you can get a white dwarf explosion,” Jha said.

 

Weak supernova

 

The weak supernova, SN 2012Z, is in galaxy NGC 1309 which is 110 million light-years away and discovered in the Lick Observatory Supernova Search in January 2012.

 

Hubble’s Advanced Camera for Surveys also observed NGC 1309 for several years before the supernova outburst, thus letting scientists compare before-and-after images.

 

After studying the object’s colors and comparing with computer simulations, the team concluded this was the light from a star that lost its outer hydrogen envelope and revealed its helium core.

 

The team plans to use Hubble in 2015 to observe the area again. This will allow the supernova’s light to dim to reveal any possible zombie star and helium companion.

 

Team member Ryan Foley of the University of Illinois at Urbana-Champaign said they predicted these supernovae were produced by a white dwarf and helium star binary system, way back in 2009.

 

“There’s still a little uncertainty in this study, but it is essentially validation of our claim,” Foley said.

 

Improved models

 

The astronomers hope their new findings will lead to improved models for these white dwarf explosions and a better understanding of the relationship between Type Iax and normal Type Ia supernovae.

 

A separate article on the Los Angeles Times said the discovery of this zombie star was "special" since astronomers have never actually seen a Type Ia star before it exploded as they are too faint. — Joel Locsin/TJD, GMA News