Extremely rare collision of two white dwarfs creates zombie star
Two white dwarfs fused together, rising from the dead.
Jackson RyanFormer Science Editor
Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, he realized, was the best job in the world -- it let him tell stories about space, the planet, climate change and the people working at the frontiers of human knowledge. He also owns a lot of ugly Christmas sweaters.
Researchers at the University of Bonn in Germany and the Russian Academy of Sciences have spotted an incredibly unusual and rare star in the middle of a cloud of gas around 10,000 light years from Earth.
The star, dubbed J005311, appears to have risen from its cosmic grave after two dead stars collided with one another in the constellation Cassiopeia. The findings, published in Nature on May 21, reveal the nature of the exotic zombie star and its unusual properties. The team discovered the bizarre object using data from NASA's Wide-field Infrared Survey Explorer (WISE) space telescope and subsequently observed it using a ground-based telescope at Russia's Special Astrophysical Observatory.
At the end of a small star's lifetime, when all of its fuel has been exhausted, it turns into a "white dwarf" -- a tiny, dense, dead star. For the most part, a white dwarf is done for after that. However, researchers at Bonn examined the radiation emitted by the strange star and found that it was lacking in both hydrogen and helium, usually present in a white dwarf.
Due to J005311's unusual emission signal, the researchers suspect what they've detected is the result of a cosmic fusion between two white dwarfs that circled one another for billions of years.
"Such an event is extremely rare," explains Gotz Gräfener, co-author on the study, in a press release. "There are probably not even half a dozen such objects in the Milky Way, and we have discovered one of them."
Generally, collisions of white dwarfs end up in huge stellar explosions, known as supernovae. But J005311 didn't explode. Instead, it was reanimated and started burning again.
It shines about 40,000 times brighter than our sun, has a strong magnetic field and its stream of stellar winds are moving at 16,000 kilometers per second (approx. 9950 miles per second). At approximately 360,000 degrees Fahrenheit (200,000 degrees Celsius), it's also incredibly hot.
What fate awaits the new star? Death, naturally. The exceptional event has only delayed its demise by a few thousand years. Its second run at life will be over once it has, again, exhausted all its fuel. At that point it will collapse into a tiny star and explode.
NASA's Hubble telescope delivers stunning new space pictures