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SALT LAKE CITY - The Hubble telescope has once again caught an astounding event in the universe - a giant and distant planet getting its face melted off.
HD 189733b, a giant blue gas planet more similar to Jupiter than Earth, sits very close to its star — just 1/13 the distance from the Earth to the sun. Even thought the temperature on the planet is a paltry 1000 degrees Celsius, scientists have noticed that HD 189733b's atmosphere has been evaporating away at an alarming rate — much too fast given the temperature.
Why? Because of the fierce x-ray radiation of its star. 3 million times as fierce as the radiation that hits Earth, in fact.
"X-ray emissions are a small part of the star's total output, but it is the part that it is energetic enough to drive the evaporation of the atmosphere," said Peter Wheatley of the University of Warwick, a co-author of the study. "This was the brightest X-ray flare from (the star) of several observed to date, and it seems very likely that the impact of this flare on the planet drove the evaporation seen a few hours later with Hubble."
Although the above photograph is an artist rendition, it is a good approximation of what's happening to HD 189733b. X-ray flare ups pack a potent punch and strip the the planet of its atmosphere at a rate of at least 1000 tonnes per second. The x-rays heat the upper atmosphere so much that gasses are able to absorb enough energy to escape the planet's gravity.
It is thought that a process similar to this could be responsible for the creation of "super earths", that is giant rocky planets similar in composition to Earth but many times larger. They may have started out as gaseous planets like HD 189733b, and simply had their atmosphere stripped away, bit by bit.
