What happens when you smash two really big, hot objects together? They explode, right?
Maybe that's not news on the Hollywood stunt-explosion level. But on the stellar front, it's causing some raised eyebrows. Researchers at the Harvard-Smithsonian Center for Astrophysics have taken a second look at a supernova observed last year, and are realizing that it was most likely caused by the collision of two white dwarf stars, instead of the explosion of just one, as previously believed.
White dwarf supernova are a common feature in the universe, generally formed when the star takes on gas from a companion before a catastrophic nuclear fusion reaction blows it apart. Known as Type Ia, they are generally distinguished by the lack of hydrogen in their makeup.
The 2006gz supernova was thought to have emerged this way too – until researchers noted that it was too large, and contained the largest amount of unburned carbon ever seen in a nova of this kind. This led researchers to conclude that in fact two white dwarfs had been companion stars that spiraled around each other until merging and exploding.
This is interesting by itself (after all, what titanic explosion isn't?), since astronomers had only speculated about, never observed a supernova produced this way. But it raises some concerns more broadly through the astronomical world. Because of their fairly standard origins and brightness, Type Ia supernovas are used as "standard candles," or intergalactic mileposts, in determining long-range cosmic distances.
If it now turns out that novas appearing as Type Ia may indeed have different and more complex origins, and might therefore vary more than expected, this may call into question some of astronomer's other calculations, researchers said.
White Dwarf "Sibling Rivalry" Explodes into Supernova [Harvard-Smithsonian press release]
(Image: Artist's conception of white dwarf pair's death spiral. Credit: Credit: NASA/Dana Berry, Sky Works Digital)
