A supernova is the catastrophic explosion of a star, and thermonuclear supernovae, in particular, refer to the complete destruction of a white dwarf star, leaving nothing behind.
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So when a team of astronomers looked at the location of the strange thermonuclear supernova SN 2012Z using the Hubble Space Telescope, they were shocked to discover that the star survived the explosion. Not only did it survive, but the star was even brighter following the supernova than it had been before.
Lead author on the recent study, Curtis McCauley, a postdoctoral researcher at the University of California, Santa Barbara and Las Cumbres Observatory, published the findings in The Astrophysical Journal, and presented them at a press conference at the 240th meeting of the American Astronomical Society.
These puzzling findings give us new information regarding the origins of some of the most common, and mysterious, explosions in the universe.
These thermonuclear supernovae, also called Type Ia supernovae, are some of the most important tools in astronomers’ toolkits for measuring cosmic distances. Beginning in 1998, observations of these explosions revealed that the universe was expanding at an ever-accelerating rate.
This is believed to be due to dark energy, the discovery of which won the Nobel Prize in Physics in 2011.
Despite their vital importance to astronomy, the origins of thermonuclear supernovae are not well understood. Astronomers agree that it is a destruction of white dwarf stars – stars roughly the mass of the Sun the size of the Earth.
The cause of the explosion of stars is unknown. One theory is that the white dwarf steals matter from the companion star. When the white dwarf becomes very heavy, thermonuclear reactions in the core ignite and lead to a rapid explosion that destroys the star.
SN 2012Z was a peculiar type of thermonuclear explosion, sometimes called a Type Iax supernova, one of the weaker, more conventional type (Type Ia) supernovae. Because the explosions are less powerful and slower, some scientists have hypothesized that they were a failed Type Ia supernova. The new observations confirm this hypothesis, as astronomers were surprised when they pointed the NASA Hubble Space Telescope in the direction of thermonuclear supernova SN 2012Z and found that there was still a star.
Andy Howell, a professor at the University of California, Santa Barbara, said in a statement: “Nature tried to hit this star, but it came back stronger than we imagined. Still the same star, but he’s back in a different form. Death has passed.”
In the paper, Howell documents the discovery that the star not only survived, but grew even brighter than before.
“No one expected to see a brighter star,” explained lead author Curtis McCauley, a postdoctoral researcher at the University of California, Santa Barbara and Las Cumbres observatory. That was a real mystery. There were signs that SN 2012Z was an unusual supernova explosion. It was slower and less dimmer, the kind of supernova that some astronomers believe may be associated with a failed supernova that might leave a black hole behind.”
In this case, the star appears to be halfway up, exploding and getting brighter in the process. But the explosion was not powerful enough to rip the star apart and blast all of its material into deep space, forming the bright nebulae that supernovae often leave behind.
“Now we need to understand what makes a supernova fail,” McCauley noted.
Source: CNET
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