Could alien life cope with the radiation in a 3-Star Alpha Centauri system?

This X-ray image (inset) of the two brightest stars in the three-star Alpha Centauri system, was captured by NASA’s Chandra X-ray Observatory on 2 May 2017. The visible-light image of the Alpha Centauri system and its surroundings was taken by a telescope in northern Chile run by the European Southern Observatory.

(X-ray: NASA/CXC/University of Colorado/T. Ayres; Optical: Zdeněk Bardon/ESO)

Well, two out of three is not bad.

The level of X-ray radiation streaming of Alpha Centauri A and B — two of the three stars in the nearest solar system, our own — are similar to those emitted by our own sun, according to a new study based on observations from NASA’s Chandra X-ray Observatory.

“This is very good news for Alpha Cen AB in terms of the ability of the possible existence of life on one of the planets in order to survive radiation attacks from the stars,” study lead author Tom Ayres, of the University of Colorado in Boulder, said in a statement. “Chandra shows us that life needs a fighting chance on planets around these stars.” [Mission to Alpha Centauri: Breakthrough Starshot in Photos]

Alpha Centauri is roughly 4.2 light years from the sun. The three-star system is composed of the close orbit to the A-and B-pair (astronomers often confuse “AB”) and a distant companion called Proxima Centauri. A and B are stars like the sun, while Proxima Centauri is a small, dim red dwarf.

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No planets have been confirmed around either Alpha Cen A or B, so all discussion of these worlds is strictly hypothetical. (Astronomers continue to look, however.)

Proxima Centauri hosts approximately Earth-size planet, known as Proxima b, in the “habitable zone” —the range of distances from a star where liquid water can exist on earth. But red dwarfs are incredibly active star, often firing from superpowerful flares that bathe in orbit around worlds in the penalties of radiation. So, many scientists question the habitability of the Proxima b, to speculate that an atmosphere it once had was stripped long ago by the activity of the star.

But the radiation story is very different for Alpha Cen AB, the new study reports. Chandra is the monitoring of the two stars about every six months since 2005, and Ayres dug into this data.

He found that a habitable zone planets around Alpha Cen A would get lower X-ray doses than comparable worlds circling our own sun. Alpha Cen B’s habitable zone doses are about five times larger than those in our solar system not yet high enough to be an eye-catcher for the living, Ayres said.

Ayres presented the new study on Wednesday (6 June) at the 232nd meeting of the American Astronomical Society meeting in Denver. Some of the results were published in January 2018, in the journal of the Research Notes of the American Astronomical Society.

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