Planet orbiting dying star may hold clue to Earths future

An international team of astronomers have discovered a planet orbiting a star near the end of its life, which they say could offer clue to Earths future.

Washington, Sept 13 : An international team of astronomers have discovered a planet orbiting a star near the end of its life, which they say could offer clue to Earth's future.

In four to five billion years, the Sun will exhaust its hydrogen fuel, expand enormously as a red giant and expel its outer layers in an explosive helium flash.

The planet discovered by the researchers, "V 391 Pegasi b," has survived all those changes to its sun, "V 391 Pegasi," a faint star in the constellation of Pegasus. Researchers are now looking forward to see what happens to the planet when the V 391 Pegasi extinguishes itself.

"The exciting thing about finding a planet around this star is that it indicates that planetary systems can survive the giant phase and the helium flash of their parent star," said Steve Kawaler, an Iowa State University professor of physics and astronomy.

"It bodes well for the survival of our own Earth in the distant future. Before V 391 Pegasi lost its outer regions at the helium flash, the planet orbited the star at about the same distance that the Earth orbits our Sun," he said.

He, however said, "We shouldn't take too much heart in this - this planet is larger than Jupiter, so a smaller planet like the Earth could still be vulnerable".

As part of the research, the scientists calculated the irregularities of the star's orbital motion to ensure that they were caused by the orbiting planet.

Calculations revealed that at the present time, V 391 Pegasi b has an orbital distance 1.7 times the medium distance between the Earth and the Sun.

As stars age and reach their red giant phase, they undergo an enormous expansion (with their volume increasing by a factor of millions) that can easily reach and engulf their inner planets.

"The same will happen to the sun. As far as our planets are concerned, we expect Mercury and Venus to disappear in the Sun's envelope, whereas Mars should survive. The fate of the Earth is less clear because its position is really at the limit: it appears more likely that the Earth will not survive the red giant expansion of the Sun either, but it is not for sure," said Roberto Silvotti from the INAF-Osservatorio Astronomico di Capodimonte in Naples, Italy.

ANI