New finding in nearby sun 'twin'

Feb. 20, 2013 at 3:41 PM
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PARIS, Feb. 20 (UPI) -- A cool layer detected in the atmosphere of Alpha Centauri A is the first evidence of the phenomenon seen in a star beyond the sun, astronomers say.

The finding of the cool layer similar to that in the sun is not only important for understanding the sun's activity but could help in the quest to discover proto-planetary systems around other stars, a release by the European Space Agency said Wednesday.

Almost a twin to the sun in mass, temperature, chemical composition and age, Alpha Centauri A provides an ideal natural laboratory to compare other characteristics of the two stars, scientists operating ESA's Herschel space telescope said.

The sun's thin outer atmosphere -- the corona -- is heated to millions of degrees while the visible surface is "only" thousands of degrees, a puzzle scientists suspect is caused by twisting and snapping of magnetic field lines sending energy rippling through the sun's atmosphere.

"The study of these structures has been limited to the sun until now, but we clearly see the signature of a similar temperature inversion layer at Alpha Centauri A," Rene Liseau of the Onsala Space Observatory in Sweden said. "Detailed observations of this kind for a variety of stars might help us decipher the origin of such layers and the overall atmospheric heating puzzle."

The three stars in the Alpha Centauri system are the nearest neighbors to the sun, at slightly more than 4 light-years distance. Alpha Centauri B has recently been in the news following the discovery of an Earth-mass planet in orbit around it.

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