The closest star to the Sun

Source: By The Financial Express

Astronomers running the world’s largest initiative to look for alien life have recently picked up an “intriguing” radio wave emission from the direction of Proxima Centauri, the closest star to our Sun, The Guardian reported.

The news has sparked renewed interest in Proxima Centauri, one of whose planets is believed to revolve in the star’s habitable zone, giving rise to the possibility that it could have, or does, sustain life.

Astronomers at the $100 million Breakthrough Listen project, started by the legendary physicist Stephen Hawking, regularly spot blasts of radio waves using two powerful telescopes– the Parkes Observatory in Australia or the Green Bank Observatory in the US. All of their findings so far, though, have been attributed either to natural sources or interference caused by humans.

Unlike the project’s previous findings, the beam picked up from the direction of Proxima Centauri–which has been named BLC1 or Breakthrough Listen Candidate 1– has two interesting characteristics. First, its signal frequency is 982 Mhz– a narrow-band value that is not transmitted by human-made spacecraft or satellites. Neither do we know of a natural astronomical phenomenon that can generate such a radio signal. Second, the apparent shift in this frequency is reportedly consistent with the movement of the planet.

This raises the possibility that the emission could be an alien “technosignature”, meaning something which provides evidence of alien technology, and could have arisen from some form of advanced extraterrestrial intelligence (ETI), as per the Scientific American.

According to the Guardian, the beam was found in the archival data of the Parkes observatory, which picked up the beam in April and May last year. It has not been spotted again. Scientists are currently working on a paper explaining BLC1, which is expected to be released early next year.

There are also reasons to believe that the signal might not mean ‘aliens’. Since only the Parkes observatory has picked up the signal, which has not appeared since, it would be impossible to verify that it came from Proxima Centauri. Another possibility could be that the signal could have been caused by something behind Proxima Centauri, or by a natural phenomenon whose existence we so far do not know of.

Proxima Centauri is 4.2 light-years away from the Sun – considered a close distance in cosmic terms. Its mass is about an eighth of the Sun’s, and it is too dim to be seen with the naked eye from Earth.

Proxima b, one of the two planets that revolve around the star, is the subject of significant curiosity. Sized 1.2 times larger than Earth, and orbiting its star every 11 days, Proxima b lies in Proxima Centauri’s “Goldilocks zone”, meaning the area around a star where it is not too hot and not too cold for liquid water to exist on the surface of surrounding planets. To give an example, the Earth is in the Sun’s Goldilocks zone.

However, this does not mean for sure that water is present on Proxima b. It could also be hostile to life, if its atmosphere has been stripped away by solar flares from Proxima Centauri. Proxima b is also tidally locked with its star, just like the Moon is to Earth– meaning one side of the planet has daylight forever, while the other side is always dark. Scientists say that it is difficult to imagine that Proxima b could have a stable climatic system under such conditions.