Alien life best sought on dying suns?
|July 5, 2011||Posted by News under Cosmology, Extraterrestrial life, Exoplanets|
At New Scientist (29 June 2011) we learn from Ken Croswell that “Dying stars hold the promise of alien life”:
WELCOME to Procyon B, a nearby star that’s light years away from the sun, and not only in distance terms. Unlike the healthy star we circle, Procyon B is dim and dying. Having thrown off its outer layers, it is puny compared with the sun. And it is so dense that were you able to scoop up a spoonful of its material, it would weighs tonnes. So unlike our sun is Procyon B, in fact, that those seeking extraterrestrial life have long overlooked the star’s potential.
University of Washington astronomer Eric Agol thinks we are too ready to dismiss such places. (You must log in to read the article. )
Agol is also featured in an MIT Technology Review, Physics ArXiv Blog post on the hypothesis that white dwarfs are habitable zones, providing much more detail:
most searches for exoplanets have focused on nearby stars like our own.
Today, Eric Agol at the University of Washington in Seattle points out that planet hunters may be missing a trick. He says that white dwarfs could be good targets for exoplanet searches.
He points out that they are as common as Sun-like stars, that the most common ones have a surface temperature of about 5000 K and that this should produce a habitable zone at distances of about 0.01 AU for periods in excess of 3 billion years. That’s long enough for something interesting to have emerged on these bodies.
What’s more, any Earth-sized planet orbiting at this distance ought to be easy to spot as it passes in front of the tiny disc of a white dwarf.
There is a caveat, however. As stars age, they form red giants that engulf everything within a radius of about 1 AU. So any planet orbiting a white dwarf in the habitable zone would have to have migrated there after the white dwarf formed.
That’s a little discouraging but it’s not entirely impossible. Many theories of solar system formation assume that planet migration plays an important role. “White Dwarfs, Habitable Zones and Other Earths” (3/17/2011)
File under: Hope springs eternal
File with: Okay, so Earth is rare, and who predicted that?
What’s SETI doing these days?
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