Hubble, Swift Detect Strange Relation between Exoplanet and its Star

The international team of astronomers have detected some remarkable changes in the atmosphere of the planet located beyond the solar system. Based on the data collected from NASA's Hubble Space Telescope the researchers noticed the atmospheric variations that occurred in response to a powerful eruption on the planets host star. This event was observed by NASA's Swift Satellite.

"The multi wavelength coverage by Hubble and Swift has given us an unprecedented view of the interaction between a flare on an active star and the atmosphere of a giant planet," said lead researcher Alain Lecavelier des Etangs at the Paris Institute of Astrophysics (IAP), part of the French National Scientific Research Center located at Pierre and Marie Curie

Discovered in 2005, exoplanet 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. Called as Hot Jupiter by the Astronomers, it was observed that the planets deep atmosphere reaches a temperature of 1900 degree Fahrenheit.

Study on Atmospheric Process

According to Vincent Bourrier, a doctoral student at IAP and a team member on the new study, "Astronomers have been debating the details of atmospheric evaporation for years, and studying HD 189733b is our best opportunity for understanding the process."

Even though HD 189733b's atmosphere wasn't thought to be evaporating astronomers knew the potential was there. The atmospheric gases extend far beyond the planetary "surface" allowing stellar light to pass through, and in previous observations astronomers were able to get a peek into what chemical compounds surround HD 189733b. The system is just 63 light-years away, so close that its star can be seen with binoculars near the famous Dumbbell Nebula. This makes HD 189733b an ideal for studying the processes that drive atmospheric escape.
"The planet's close proximity to the star means it was struck by a blast of X-rays tens of thousands of times stronger than the Earth suffers even during an X-class solar flare, the strongest category," said co-author Peter Wheatley, a physicist at the University of Warwick in England.