Hottest extrasolar planets temperature is an unimaginable 3700 degrees

US astronomers have found what they say is the hottest extrasolar planet till date, a scalding 3700 degrees, on the side facing its star.

Washington, May 10 : US astronomers have found what they say is the hottest extrasolar planet till date, a scalding 3700 degrees, on the side facing its star.

A bit smaller than Saturn, HD 149026b is however, more massive than the ringed planet and is suspected to have a core 70-90 times the mass of the Earth.

According to the researchers, it has more heavy elements (material other than hydrogen and helium) than existing in our entire solar system, outside the Sun.

"HD 149026b is simply the most exotic, bizarre planet. It's pretty small, really dense, and now we find that it's extremely hot," said Joseph Harrington, Assistant Prof. of Physics and Planetary Sciences at the University of Central Florida.

Using NASA's Spitzer infrared space telescope, Harrington and his team observed the tiny planet disappear behind its star and reappear. Although the planet cannot be seen separately from the star, the dimming of the light that reached Spitzer, enabled the team to calculate how much light the planet was emitting, and consequently what was the temperature on the side of the planet facing its star.

According to the researchers, for HD 149026b to reach 3700 degrees, it must absorb essentially all the starlight that reached it.

"This means the surface must be blacker than charcoal, which is unprecedented for planets. The planet would also have to re-radiate all that energy in the infrared. The high heat would make the planet glow slightly, so it would look like an ember in space, absorbing all incoming light but glowing a dull red," said Harrington.

Drake Deming, of NASA's Goddard Space Flight Center in Greenbelt, MD, and a co-author of the paper in the journal Nature, said: "This planet is off the temperature scale that we expect for planets, so we don't really understand what's going on".

"There may be more big surprises in the future," Deming added.

ANI