28-06-2012 08:19 An international team of astronomers using data from NASA’s Hubble Space Telescope has detected significant changes in the atmosphere of a planet located beyond our solar system. The scientists conclude the atmospheric variations occurred in response to a powerful eruption on the planet’s host star, an event observed by NASA’s Swift satellite. The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about 14 percent larger and more massive. The planet circles its star at a distance of only 3 million miles, or about 30 times closer than Earth’s distance from the sun, and completes an orbit every 2.2 days. Its star, named HD 189733A, is about 80 percent the size and mass of our sun. Astronomers classify the planet as a “hot Jupiter.” Previous Hubble observations show that the planet’s deep atmosphere reaches a temperature of about 1900 degrees Fahrenheit (1030 C). HD 189733b periodically passes across, or transits, its parent star, and these events give astronomers an opportunity to probe its atmosphere and environment. In a previous study, a group led by Lecavelier des Etangs used Hubble to show that hydrogen gas was escaping from the planet’s upper atmosphere. The finding made HD 189733b only the second-known “evaporating” exoplanet at the time. The system is just 63 light-years away, so close that its star can be seen with binoculars near the famous Dumbbell, or Apple Core, Nebula. This makes HD 189733b an ideal target for studying the processes that drive …

Visit link: