Dying stars may still host habitable planets, astronomer say

TEL AVIV, Israel, April 24 (UPI) -- White dwarfs are dying stars that will eventually cool and fade away but evidence suggests they can still support habitable planets, scientists in Israel say.

Dan Maoz of Tel Aviv University's School of Physics and Astronomy says advanced technology likely to become available within the next decade should make it possible to detect biomarkers surrounding such planets -- including oxygen and methane -- that indicate the presence of life.

Maoz and his colleague Avi Loeb suggest the James Webb Space Telescope, set to be launched by NASA in 2018, will be capable of detecting oxygen and water in the atmosphere of an Earthlike planet orbiting a white dwarf after only a few hours of observation time -- much more easily than for an Earthlike planet orbiting a sun-like star.

When an Earthlike planet orbits a normal star, Maoz said, "the difficulty lies in the extreme faintness of the signal, which is hidden in the glare of the 'parent' star."

That glare would be greatly reduced if the parent star were a white dwarf, the researchers said.

"In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs," Loeb said.

Maoz agreed, noting if "all the conditions are right, we'll be able to detect signs of life" on planets orbiting white dwarf stars using the much-anticipated JWST, designed to look into the infrared region of the light spectrum where biomarkers are prominent.

An abundance of heavy elements already observed on the surface of white dwarfs suggest rocky planets orbit a significant fraction of them, the researchers said, and a space telescope survey of 500 of the closest white dwarfs might spot one or more habitable planets.