A powerful explosion on a distant star seems to have triggered partial evaporation of the atmosphere of a closely orbiting planet.

Alain Lecavelier des Etangs of the Paris Institute of Astrophysics and his colleagues used data from the Hubble Space Telescope to examine the atmosphere of the hot, Jupiter-like exoplanet HD 189733b on two occasions. The telescope failed to detect the planet's atmosphere in April 2010, but in September 2011 it revealed an abundance of hydrogen gas rushing away from the planet. Only hours before the 2011 observations, NASA's Swift satellite had detected a large X-ray flare on the parent star. Energy from this flare could have prompted evaporation of the hydrogen atoms, the authors suggest.

Astron. Astrophys. http://dx.doi.org/10.1051/0004-6361/201219363 (2012)