September 07, 2011
Spinning White Dwarf Stars Future Supernovas

Thousands of spinning stellar time bombs could be scattered all over the Milky Way Galaxy.

In the Hollywood blockbuster "Speed," a bomb on a bus is rigged to blow up if the bus slows down below 50 miles per hour. The premise - slow down and you explode - makes for a great action movie plot, and also happens to have a cosmic equivalent.

New research shows that some old stars might be held up by their rapid spins, and when they slow down, they explode as supernovae. Thousands of these "time bombs" could be scattered throughout our Galaxy.

"We haven't found one of these 'time bomb' stars yet in the Milky Way, but this research suggests that we've been looking for the wrong signs. Our work points to a new way of searching for supernova precursors," said astrophysicist Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics (CfA).

We need to identify all the spinning white dwarfs in our neighborhood and try to calculate when each will explode and potentially damage our ozone layer.

The specific type of stellar explosion Di Stefano and her colleagues studied is called a Type Ia supernova. It occurs when an old, compact star known as a white dwarf destabilizes.

Back in 1998 some astrophysicists claimed a supernova would have to be within within 10 parsecs (30 light years) of Earth to cause us a problem and no star that close to Earth poses will go supernova in the next several million years. But if the original report above is correct in arguing that past methods of searching for supernova precursors aren't good enough then perhaps some nearby supernova precursors haven't been identified.

The 10 parsec minimum distance for a supernova threat might be overly optimistic too. In 2006 supernova SN 2006gy exploded with a light intensity 100 greater than the typical supernova and such a supernova could cause us problems at a greater distance.

Suppose astrophysicists some day discover a supernova precursor nearby due to explode in some decades or a couple of centuries from now. Could we prepare any space-based protection against the ozone loss? Or would we want to make UV shields closer to ground or move more of our civilization underground in preparation?

Share |      Randall Parker, 2011 September 07 09:41 PM  Dangers Natural General


Comments
Fat Man said at September 7, 2011 10:13 PM:

"try to calculate when each will explode and potentially damage our ozone layer."

I think it would be the Boss, flicking the lights to warn us that closing time is near.

anonyq said at September 8, 2011 6:28 PM:

10 parsec is awfully close by in astronomical terms as the closest star is more than a parsec away so i don't think there is any reason to worry. After checking the list for the 70 known stars with 5 parsec i can say that none of them is a white dwarf.


Number of stars in the Milky way = 200 - 400 billion
average number of supernova in the Milky Way = 1 per 50 year
Number of stars within 10 parsec = (70*8=560) less than a 1000

this leads to

probability that the sun will be with 10 parsec of a supernova = less than 1 in 10 billion years *)


*) supernova's are not randomly distributed in the milky way, including that would lower sol changes significantly

PacRim Jim said at September 9, 2011 3:11 PM:

Wish we had one of them doomsday white dwarfs.

Kris said at September 10, 2011 9:21 PM:

We must not allow a doomsday white dwarf gap!

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