Huge temperature variations occur in just hours

Jan 29, 2009 10:36 GMT  ·  By

HD 80606b, a gaseous exoplanet discovered in 2001 by a Swiss research team, offered astronomers a very interesting insight into its inner functions. Analysis revealed the fact that temperatures on the giant, which is four times the size of Jupiter, vary by as much as 1,000 degrees Fahrenheit (roughly 555 Celsius) within time frames as short as 6 hours. These changes in climate trigger shock-wave storms, which travel the entire surface of the celestial body faster than the speed of sound and bring about devastating heat storms. High-speed winds are also generated at a very high rate, and the chances of anything standing in the way of these waves are very close to zero.

Regularly, astronomers say, this planet orbits its star at a safe distance, as if it were between Earth and Venus in our solar system. But, for portions of one day in its year (which is equivalent to 111.4 Earth days) it moves in near the star at a distance roughly equivalent to 0.03 astronomical units (AU). For perspective, consider that an AU is the mean distance between Earth and the Sun.

So, basically, it could look like the planet literally brushes past its star. This happens because of its eccentric orbit, which has the most bizarre shape of all exoplanets thus far identified.

"If you could float above the clouds of this planet, you'd see its sun growing larger and larger at faster and faster rates, increasing in brightness by almost a factor of 1,000," explains University of California in Santa Cruz astrophysicist Gregory Laughlin, who also authored the new report detailing these finds in the January 29th issue of the journal Nature.

"That heating is so intense it's basically like an explosion on the side of the planet that's getting baked by the star. That generates these extraordinary storms that begin to echo around the planet," the scientist shared with Space.

"As the atmosphere heats up and expands, it produces very high winds, on the order of 5 kilometers per second (3 miles per second, or more than 11,000 mph), flowing away from the day side toward the night side. The rotation of the planet causes these winds to curl up into large-scale storm systems that gradually die down as the planet cools over the course of its orbit," adds UCSC researcher Jonathan Langton, who was also involved in the new study.

He adds that the exoplanet will again move in front of its star, a process called transition, on February 14th. This will allow astronomers to get a better view on it, and also to refine their still-rough calculations on how HD 80606b orbits its star.