Published: June 6, 2018
Alpha Centauri

An image showing the location of Alpha Centauri in the night sky with the X-ray signatures (inset) of stars Alpha Centauri A and B. (Credit: Optical: 
Zdeněk Bardon/ESO; X-ray: NASA/CXC/University of Colorado/T.Ayres)

In humanity’s search for life outside our solar system, one of the best places scientists have considered is Alpha Centauri, a system containing the three nearest stars beyond our sun. 

A new study by CU Boulder’s Tom Ayres used more than a decade of data from NASA’s Chandra X-ray Observatory to provide encouraging news about one key aspect of planetary habitability. It indicates that any planets orbiting the two brightest stars in the Alpha Cen system are likely not being pummeled by large amounts of X-ray radiation from their host stars.

X-rays and related space weather effects are bad for unprotected life, directly through high radiation doses and indirectly through stripping away planetary atmospheres—a fate thought to have been suffered by Mars in our own solar system.

Alpha Centauri is a triple-star system located just over four light years, or about 25 trillion miles, from Earth. While this is a large distance in terrestrial terms, it is much closer than the next nearest sun-like stars.

“Because it is relatively close, the Alpha Centauri system is seen by many as the best candidate to explore for signs of life,” said Ayres, a senior research associate in the Center for Astrophysics and Space Astronomy (CASA). “The question is, will we find planets in an environment conducive to life as we know it?”

Tom Ayres presented his results at press briefing today at the 232rd meeting of the American Astronomical Society in Denver, Colorado. Some of these results were published in January 2018 in the Research Notes of the American Astronomical Society.

Read the full story from the Chandra X-ray Observatory.

Credit: Chandra X-ray Observatory