A Jupiter-size planet around a distant star has given astronomers a rare glimpse into the effects of space weather beyond our solar system: a view of an alien world unleashing an intense plume of gas triggered by an eruption from its parent star.
HD 189733b is a gas giant planet similar to Jupiter, but orbits extremely close to its star, just one-thirtieth of the distance between Earth and the sun. While the parent star, named HD 189733A, is slightly smaller and cooler than the sun, the climate of the alien world is still exceptionally hot, with temperatures above 1,830 degrees Fahrenheit (1,000 degrees Celsius).
The exoplanet’s close proximity to its star also means its upper atmosphere is constantly battered by energetic extreme-ultraviolet and X-ray radiation. According to the researchers, this makes HD 189733b a fascinating place to study how stellar activity affects an alien planet’s atmosphere.
Despite HD 189733b’s extreme climate, the atmosphere alone is not hot enough to evaporate at such a staggering rate. Rather, the evaporation is thought to be caused by powerful doses of X-ray and extreme-ultraviolet radiation from the parent star. Based on their calculations, the star’s eruptions are 20 times more powerful than those on the sun, and HD 189733b likely receives 3 million times more X-ray radiation than Earth.
Credit: L. Calçada/NASA, ESA