Hubble finds supernova star system linked to potential 'zombie star'

August 6, 2014, NASA

The two inset images show before-and-after images captured by NASA’s Hubble Space Telescope of Supernova 2012Z in the spiral galaxy NGC 1309. The white X at the top of the main image marks the location of the supernova in the galaxy. Credit: NASA, ESA
( —Using NASA's Hubble Space Telescope, a team of astronomers has spotted a star system that could have left behind a "zombie star" after an unusually weak supernova explosion.

A typically obliterates the exploding white dwarf, or dying star. On this occasion, scientists believe this faint supernova may have left behind a surviving portion of the dwarf star—a sort of zombie star.

While examining Hubble images taken years before the stellar explosion, astronomers identified a blue companion star feeding energy to a white dwarf, a process that ignited a nuclear reaction and released this weak supernova blast. This supernova, Type Iax, is less common than its brighter cousin, Type Ia. Astronomers have identified more than 30 of these mini-supernovas that may leave behind a surviving white dwarf.

"Astronomers have been searching for decades for the star systems that produce Type Ia supernova explosions," said scientist Saurabh Jha of Rutgers University in Piscataway, New Jersey. "Type Ia's are important because they're used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes. The similarities between Type Iax's and normal Type Ia's make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified. This discovery shows us one way that you can get a white dwarf explosion."

The team's results will appear in the Thursday, Aug. 7 edition of the journal Nature.

The weak supernova, dubbed SN 2012Z, resides in the host galaxy NGC 1309 which is 110 million light-years away. It was discovered in the Lick Observatory Supernova Search in January 2012. Luckily, Hubble's Advanced Camera for Surveys also observed NGC 1309 for several years prior the supernova outburst, which allowed scientists to compare before-and-after images.

Curtis McCully, a graduate student at Rutgers and lead author of the team's paper, sharpened the Hubble pre-explosion images and noticed a peculiar object near the location of the supernova.

"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," McCully said.

After studying the object's colors and comparing with computer simulations of possible Type Iax progenitor systems, the team concluded they were seeing the light of a star that had lost its outer hydrogen envelope, revealing its helium core.

The team plans to use Hubble again in 2015 to observe the area, giving time for the supernova's light to dim enough to reveal any possible zombie star and helium companion to confirm their hypothesis.

"Back in 2009, when we were just starting to understand this class, we predicted these supernovae were produced by a white dwarf and helium star binary system," said team member Ryan Foley of the University of Illinois at Urbana-Champaign, who helped identify Type Iax supernovae as a new class. "There's still a little uncertainty in this study, but it is essentially validation of our claim."

One possible explanation for the unusual nature of SN 2012Z is that a game of seesaw ensued between the bigger and smaller of the star pair. The more massive star evolved more quickly to expand and dump its hydrogen and helium onto the smaller star. The rapidly evolving star became a white dwarf. The smaller star bulked up, grew larger and engulfed the white dwarf. The outer layers of this combined star were ejected, leaving behind the white dwarf and the helium core of the companion star. The white dwarf siphoned matter from the companion star until it became unstable and exploded as a mini-supernova, leaving behind a surviving zombie star.

Astronomers already have located the aftermath of another Type Iax supernova blast. Images were taken with Hubble in January 2013 of supernova 2008ha, located 69 million light-years away in the galaxy UGC 12682, in more than four years after it exploded. The images show an object in the area of the supernova that could be the zombie star or the companion. The findings will be published in The Astrophysical Journal.

"SN 2012Z is one of the more powerful Type Iax supernovae and SN 2008ha is one of the weakest of the class, showing that Type Iax systems are very diverse," explained Foley, lead author of the paper on SN 2008ha. "And perhaps that diversity is related to how each of these explodes. Because these supernovae don't destroy the white dwarf completely, we surmise that some of these explosions eject a little bit and some eject a whole lot."

The astronomers hope their new findings will spur the development of improved models for these white dwarf explosions and a more complete understanding of the relationship between Type Iax and normal Type Ia supernovae and their corresponding star systems.

Explore further: Astronomers discover new kind of supernova

More information: Nature paper: … ull/nature13615.html

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2 / 5 (4) Aug 07, 2014
U pretty much nailed it. Nice work constant!
1 / 5 (2) Aug 08, 2014
"Since the time of Langmuir, we know that a double layer is a plasma formation by which a plasma — in the physical meaning of this word — protects itself from the environment. It is analogous to a cell wall by which a plasma — in the biological meaning of this word — protects itself from the environment. If an electric discharge is produced between a cathode and an anode there is a double layer, called a cathode sheath, produced near the cathode that accelerates electrons which carry a current through the plasma. A positive space charge separates the cathode sheath from the plasma. Similarly, a double layer is set up near the anode, protecting the plasma from this electrode. Again, a space charge constitutes the border between the double layer and the plasma. All these double layers carry electric currents." Alfven
There you go cupcake.

1 / 5 (2) Aug 08, 2014
"We put the theory in the textbooks because it sounds right. But we don't really know it's right, and I think people are beginning to worry," says Robert Kirshner, a supernova researcher at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts. "We keep saying the same thing, but the evidence for it doesn't get better, and that's a bad sign.""There's a lot of holes in the story." "I wouldn't say it's a crisis," "But if you ask, 'Are the pieces falling into place?' I'd say the answer is no."
"is a little bit of 'the emperor has no clothes,' " as Lars Bildsten, an astrophysicist at the Kavli Institute, put it.
Keep on nailing it!
1 / 5 (2) Aug 14, 2014
Almost fifty years ago, Dr Charles Bruce of the UK Electrical Research Association identified planetary nebulae as bipolar electrical discharges from a central star, standard cosmology ignores these findings as well as the contradictions to every expectation of the thermonuclear fusion model for the sun.
I'm not sure what history your reading, but the Eighties was heyday for Alfven validations with instruments being put into space showing that the scientists who mocked and ridiculed were the true fools. Do a search and see how instrumental his contributions to physics and thinking still is today because your perspective is completely off, but I guess that's why I commented in the first place.
"...Mathematical theory, is only an approximation, applicable to specific situations, and thus has very real limits..."
1 / 5 (2) Aug 15, 2014
Thank you. Feel better?
Charles was limited by small minded men, and like Alfven it took equipment in space to validate his work not some mathematical theory.
Thanks for the heads up, some awesome stuff. Amazing amounts of reference material!
1 / 5 (2) Aug 16, 2014
Checked out those other links, some interesting ideas out there. Probably nothing any more wacky then big bangs and black holes if you really think about it.
The surface of the sun stuff was also interesting, but I'm partial to this guys take on it
Pierre-Marie Robitaille

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