spacetoday.net: "Superstorm" found on exoplanet

Posted: Thu, Jun 24, 2010, 7:30 AM ET (1130 GMT)
Superstorm on exoplanet HD209458b (ESO)

Astronomers announced this week evidence for a powerful "superstorm" in the atmosphere of an extrasolar planet. In a paper published in the current issue of the journal Nature, scientists said they found signs of powerful winds in the atmosphere of HD 209458b, a "hot Jupiter" exoplanet orbiting just 0.05 AU from its parent star. Astronomer studied the planet as it transited the disk of the star, using a high-resolution spectrograph mounted on the European Southern Observatory's Very Large Telescope to measure variations in carbon monoxide lines as light from the star passes through the planet's dense atmosphere. Those spectral variations indicated that winds in the atmosphere are blowing at speeds of 5,000 to 10,000 km/h, likely caused by the fact that the planet is tidally locked to the star so that only one side is heated, causing large temperature variations and thus powerful winds.