Friday, April 08, 2011

Rare Binary White Dwarfs Discovered

I just read this killer article in the Daily Galaxy about white dwarf stars. To be precise a binary pair of white dwarfs that are orbiting each other once every 39 minutes! Oh wait, it gets weirder. In a few million years they will collide and merge to create a single star! Ok I hear the comments. So, you have a rare event here, but what is so strange about 2 stars colliding to make one?

To answer that we really should take a moment to figure out just what a white dwarf star really is. The Daily Galaxy article really does it best:
  • White Dwarfs are among the oldest objects in the galaxy and are the remnants of the earliest phases of star formation. No bigger than the Earth, they are formed when a star like our Sun ends its life.
And weirder still:
  • Out of the 100 billion stars in the Milky Way, only a handful of merging white dwarf systems are known to exist. The latest discovery will be the first of the group to merge AND be reborn.
That's right, two dead remains of long dead stars will combine to make a brand new star, not a bunch of junk from two dead stars... But you thought that it can't get any weirder? Oh my...we have only scratched the surface. Check this:
  • The two white dwarfs orbit each other at a distance of 140,000 miles -- less than the distance from the Earth to the Moon. (Their orbital speeds reach upwards) of 270 miles per second or 1 million miles per hour!

Ok, now this is important.... in the normal stream of events, when two white dwarfs collide, the produce a super-nova. But and this is a big but...(ok, I know, I could have gone there but give me a little credit for not being juvenile 24/7) for a supernova to happen the mass must reach about 40% more than the mass of our sun. Now the binary system has one viable star which masses 17 percent of Sol and the second companion white dwarf weighs 43 percent. Now my high school math tells me that comes out to somewhere 60% or so. Instead of going boom, the new what....zombie star?... will begin fusing helium (which is the main element in the two dwarfs) and enter onto main sequence again, like a normal star.

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