London: Corot-7b, the smallest-known planet
outside our solar system, probably was a Saturn-sized "gas
giant" planet, American scientists suggest.
According to a research presented at the 215th American
Astronomical Society meeting, the planet, with diameter 70 per
cent larger than that of the earth, has had much of its mass
boiled away by the star's heat.
Using a computer model, the team estimated that the
planet, which orbits at one-sixtieth the distance from the
earth to the sun, once orbited at a distance 50 per cent
higher than its current one, and had about 100 times as much
mass as earth.
The team opined that as mass was burned off, the tides on
its star changed, resulting in bringing the planet closer to
the star. As it drew in closer, surface temperatures rose,
driving off more mass, BBC reported.
The researchers reckoned that if Corot-7b's orbit is not
exactly circular, then it is a hotbed of volcanic activity.
"The planet may be volcanically active if its orbit is
even slightly elliptical, rather than circular," said Rory
Barnes of the University of Washington.
The shifting gravity that Corot-7b -- spotted by the
French space-based telescope Corot -- would experience as it
moved nearer to and farther from the star in its 20-hour orbit
would stretch and squash the planet mercilessly. This would
drive friction in its interior and volcanoes on its surface.
"If conditions are what we speculate, then Corot-7b could
have multiple volcanoes going off continuously and magma
flowing all over the surface," Barnes said.
PTI
First Published: Friday, January 08, 2010, 21:54