Proxima Centauri is a red dwarf, a small and relatively cool star, which is at a distance of around 4.25 light years away from the Sun in the constellation of Centaurus.
It was discovered in 1915 and is special because it is the nearest star to our own Sun. Although it has a very low luminosity, but it’s known to undergo random increased brightness patterns due to its magnetic activity.
According to scientists, Proxima Centauri went and flared up again in March last year. This resulted in a magnificent flare so bright that it was approximately ten times brighter than the largest flare ever produced by the Sun.
Due to the ability of scientists to view this activity the previously believed notion that Proxima Centauri is being orbited by a host of planets seems no longer viable.
Why is this flare up important?
The image below shows Proxima Centauri as seen by Hubble. In November, researchers from the Institute of Astrophysics of Andalusia (IAA) in Spain detected a glow around Proxima Centauri and attributed that glow to a ring of dust.
They believed that this ring of dust was actually an asteroid belt exactly like the one orbiting our own Sun on the far side of Mars. Another such asteroid belt called the Kuiper belt has also been detected beyond Pluto.
So does this mean we are not alone after all?
n 2016, it was confirmed that the existence of this belt could mean that there is an entire planetary system, much like our own, revolving around Proxima Centauri past its exo-planet Proxima b.
The fact that dust and asteroid belts result from accretion disc of dust which results from the formation of a star and can form planets only further proved the belief.
The bad news though:
However, this idea now appears flawed and there might not be any planetary system around Proxima Centauri after all, as proposed and observed by a team of researchers led by Carnegie’s Meredith MacGregor.
They declared that the massive flare which the first team from IAA observed didn’t own an asteroid belt at all but was the result of a solar flare.
So how did two teams come up with completely different interpretations?
The data which both teams observed actually came from the same source: the Atacama Large Millimeter/submillimeter Array, a radio telescope comprising 66 antennas. This was a 10-hour data and was recorded from 21 January to 25 April 2017.
The IAA team based their findings on the average brightness of the star over these three months and came with their asteroid belt and dust cloud interpretation.
MacGregor’s team, on the other hand, didn’t look at the average brightness and instead looked at the data as a time observation.
They discovered that the star had a massive flare up, on March 24, 2017, which was a thousand times brighter than was the norm for this star within a period of 10 seconds.
So what does this data mean?
Simply put, this data means that since Proxima Centauri has an active flaring routine it would make life unsustainable on Proxima b. and any other planets, if there were any, revolving closer to it. As the star is relatively cooler, the planet Proxima b. would have to orbit closer to it for life to be sustainable.
However, the regular flare-ups of the star are strong enough to evaporate oceans. “Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean sterilized the surface,” explains MacGregor, “Suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”
But that’s not all
Not all hope is lost, however. There may still be planets around Proxima Centauri which the scientists have not discovered yet. In fact, Proxima b. was also only discovered until as recently as 2015.
It is highly likely that there are other planets around it which have gone undetected so far. However, now that the asteroid belt theory has been called into doubt scientist remain doubtful if there are more planets to be found.
“There is now no reason to think that there is a substantial amount of dust around Proxima Cen[tauri],” said co-author Alycia Weinberger of Carnegie. “Nor is there any information yet that indicates the star has a rich planetary system like ours.”