NASA Chandra & ESA ESO: Corot Star Blasts Planet With X-rays

Image and illustration of a nearby star, CoRoT-2a, and an orbiting planet, CoRoT-2b.

(Optical: NASA/NSF/IPAC-Caltech/UMass/2MASS, PROMPT; Wide field image: DSS; X-ray: NASA/CXC/Univ of Hamburg/S.Schroter et al; Illustration: CXC/M. Weiss).

A nearby star is pummeling a companion planet with a barrage of X-rays 100,000 times more intense than the Earth receives from the sun.

New data from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope suggest that high-energy radiation is evaporating about 5 million tons of matter from the planet every second. This result gives insight into the difficult survival path for some planets.

The planet, known as CoRoT-2b, has a mass about three times that of Jupiter - 1,000 times that of Earth - and orbits its parent star, CoRoT-2a at a distance roughly 10 times the distance between Earth and the moon.

The CoRoT-2 star and planet - so named because the French Space Agency's Convection, Rotation and planetary Transits, or CoRoT, satellite discovered them in 2008 - is a relatively nearby neighbor of the solar system at a distance of 880 light years.

"This planet is being absolutely fried by its star," said Sebastian Schroeter of the University of Hamburg in Germany. "What may be even stranger is that this planet may be affecting the behavior of the star that is blasting it."

According to optical and X-ray data, the CoRoT-2 system is estimated to be between about 100 million and 300 million years old, meaning that the star is fully formed.

The Chandra observations show that CoRoT-2a is a very active star, with bright X-ray emission produced by powerful, turbulent magnetic fields. Such strong activity is usually found in much younger stars.

CoRoT-9b a Temperate Planet - The new Earth

CoRoT-9b, a Jupiter-sized exoplanet thats orbits its star every 95 days, is the latest discovery of the CoRoT satellite, a project in which the German Aerospace Center (DLR) is a participant.

"This exoplanet stands out by virtue of its 'normality'. It is a very close approximation of the planets in our own solar system," says Professor Heike Rauer from the DLR Institute of Planetary Research in Berlin, who manages the German contribution to CoRoT.

CoRoT-9b lies far away from our Solar System, some 1500 light-years from Earth, and orbits a star in the constellation of the Serpent. From the duration of its orbit, it would appear that the distance between planet and star is roughly the same as the distance separating Mercury from our Sun.

CoRoT-9b is therefore an entirely normal planet - presumably a gaseous planet with relatively moderate temperatures anywhere from -20 degrees to 160 degrees Celsius, depending on whether or not it is shrouded in a highly reflective cloud layer.

The differences between its day and night sides are probably only slight. CoRoT-9b is therefore substantially different from the class of 'hot Jupiters', which orbit their central star about every three days. A planet with a short orbital period is located very close to its star and is therefore exposed to powerful stellar radiation.

It is from this that the names of the planetary classes 'hot Jupiters' and 'hot Neptunes' are derived.

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