Dying stars may clue us into extra-terrestrial life
Washington, Feb 26 : Dying stars could also host planets with life -- if they do, they might be able to clue our scientists into it within the next decade.
"In the quest for extra-terrestrial biological signatures, the first stars we study should be white dwarfs," said Avi Loeb, theorist at the Harvard-Smithsonian Centre for Astrophysics (CfA).
Loeb and his colleague Dan Maoz (Tel Aviv University) estimate that a survey of the 500 closest white dwarfs could spot one or more habitable Earths, the journal Monthly Notices of the Royal Astronomical Society reports.
This encouraging result comes from a new theoretical study of Earth-like planets orbiting white dwarf stars. For instance, oxygen could be detected in the atmosphere of a white dwarf's planet, much more easily than for an Earth-like planet orbiting a Sun-like star, according to a Harvard-Smithsonian statement.
When a star like the Sun dies, it puffs off its outer layers, leaving behind a hot core called a white dwarf.
A typical white dwarf is about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years.
Since a white dwarf is much smaller and fainter than the Sun, a planet would have to be much closer in to be habitable with liquid water on its surface.
A habitable planet would circle the white dwarf once every 10 hours at a distance of about a million miles.