Astronomers get a sizzling weather report from a distant planet

January 30th, 2009 - 3:51 pm ICT by ANI  

Washington, Jan 30 (ANI): Astronomers have observed the intense heating of a distant planet as it swung close to its parent star, providing important clues to the atmospheric properties of the planet.

The observations, by astronomers at the University of California, Santa Cruz (UCSC), enabled them to generate realistic images of the planet by feeding the data into computer simulations of the planets atmosphere.

According to Gregory Laughlin, professor of astronomy and astrophysics at UCSC, We cant get a direct image of the planet, but we can deduce what it would look like if you were there.

The ability to go beyond an artists interpretation and do realistic simulations of what you would actually see is very exciting, he said.

The researchers used NASAs Spitzer Space Telescope to obtain infrared measurements of the heat emanating from the planet as it whipped behind and close to its star.

In just six hours, the planets temperature rose from 800 to 1,500 Kelvin (980 to 2,240 degrees Fahrenheit).

Known as HD 80606b, the planet circles a star 200 light years from Earth, is four times the mass of Jupiter, and has the most eccentric orbit of any known planet.

It spends most of its 111.4-day orbit at distances that would place it between Venus and Earth in our own solar system, while the closest part of its orbit brings it within 0.03 astronomical units of its star.

The planet zips through this dramatic close encounter with its star in less than a day.

At the closest point, the sunlight beating down on the planet is 825 times stronger than the irradiation it receives at its farthest point from the star.

If you could float above the clouds of this planet, youd see its sun growing larger and larger at faster and faster rates, increasing in brightness by almost a factor of 1,000, Laughlin said.

Spitzer observed the planet for 30 hours before, during, and just after its closest approach to the star.

The planet passed behind the star (an event called a secondary eclipse) just before the moment of its closest approach.

This was a lucky break for Laughlin and his colleagues, who had not known that would happen when they planned the observation.

The secondary eclipse allowed them to get accurate measurements from just the star and thereby determine exact temperatures for the planet.

According to Laughlin, the extreme temperature swing observed by Spitzer indicates that the intense irradiation from the star is absorbed in a layer of the planets upper atmosphere that absorbs and loses heat rapidly. (ANI)

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