Alpha Centauri, a neighboring stellar system that contains the three nearest star beyond the sun, is one of the key places where astronomers have been searching for life outside the solar system.
Effect Of X-rays Radiations
NASA now revealed that data from NASA's Chandra X-ray Observatory suggest that the system, located about 4 light-years away from Earth, is more habitable to life than initially thought.
X-rays and related space weather may have a detrimental effect on unprotected life in these alien worlds. In the case of planet Mars, for instance, high doses of radiation stripped away the planet's atmosphere.
"Exoplanets of other sunlike stars can be exposed to analogous extreme high-energy transients from their hosts, with perhaps serious repercussions for habitability," Tom Ayres, of the University of Colorado Boulder, wrote in Research Notes of the American Astronomical Society.
Observations spanning more than a decade suggest that any planets orbiting the two brightest stars in the Alpha Centauri system are not likely bombarded by large amounts of x-ray radiation from their parent stars.
"Chandra shows us that life should have a fighting chance on planets around either of these stars," said Ayres.
Habitability Of Planets Orbiting Alpha Centauri's Two Brightest Stars
Astronomers have used Chandra to observe two of the system's stars about every six months since 2005. The data showed the ups and downs of X-ray activity of the two stars analogous to the 11-year sunspot cycle of the sun.
The observations revealed that the amount of X-ray radiation emitted by the stars Alpha Centauri A and Alpha Centauri B is on par with what Earth gets from the sun.
The data, in fact, revealed that the prospects for life relative to the x-ray bombardment are better around Alpha Centauri A than for our own sun. Any planets Alpha Centauri A's habitable zone would receive a lower dose of X-rays on average compared with similar planets in the solar system that orbit the sun.
Alpha Centauri B fares slightly worse, while the third star, Proxima Centauri, frequently sends out dangerous flares of X-ray radiation about 500 times that received by Earth on average, and 50,000 times during a big flare. This means that while X-ray radiations from the two other stars of Alpha Centauri are not hazardous, Proxima could be hostile to life.