Object: the exoplanet 55 Cancri b
Distance: about 40 light years
Wrapped up snug in a warm, puffy atmosphere, the gas giant planet 55 Cancri b may not realise it is living on the edge.
But it turns out the planet is at just the right distance from its star for its gassy covering to start slipping away. The discovery of this slowly evaporating exoplanet could help us better understand atmospheres in our solar system, including why some worlds have them while others don't.
David Ehrenreich of the University of Geneva, Switzerland, and colleagues had been using the Hubble Space Telescope to examine 55 Cancri e, a super-Earth in the same star system, and one that might be made of diamond.
That planet transits, or crosses, in front of its star, and the team was hoping to find out if it has an atmosphere by looking for changes in the light emitted during a transit.
They did detect hints of an atmosphere, but not the one they expected. Their results showed that nearby 55 Cancri b has an unusually large atmosphere, and that its uppermost layers skim the star.
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