First space weather report from our nearest stellar neighbour puts habitability on planet at risk

Artist’s rendering of a red dwarf star stripping the atmosphere from an orbiting planet.
(Image credit: NASA, ESA, and D. Player (STScI)

For the first time, a team of scientists has revealed a decisive link between stellar flares and radio bursts on a star, other than our Sun. The findings will enable scientists to detect and produce space weather reports from distant stars with more ease.

Based on these findings, the first space weather report of our nearest stellar neighbor Proxima Centauri is out and it seems to dash all hopes of finding life on rocky worlds orbiting it.

Proxima Centauri is only 4.244 light years away from Sun. It was discovered by Robert Innes in 1915 and it is the nearest known star to Sun.

In 2016, scientists discovered an Earth like rocky planet orbiting in Proxima Centauri’s habitable zone (or Goldilocks Zone), where water could stay in liquid state. This raised the hope of finding extraterrestrial life nearby.

But since Proxima Centauri is a cool, small red dwarf star, its habitable zone is pretty close to it. So close, even closer than what Mercury is to Sun. This makes the orbiting planets prone to intense stellar radiations that could kill any possible life form as we know it.

Even though red dwarfs are cool and small, yet they frequently release powerful stellar flares, which according to scientists is a bad sign for any possible life on planets orbiting red dwarfs.

Coronal mass ejections(CMEs) are the bigger problems than flares, these two types of eruptions on Sun are usually linked, with most powerful flares are followed by CMEs.

Our own Sun also regularly releases coronal mass ejections (CMEs)- the hot clouds of ionised particles. But since Sun is way much hotter than red dwarf stars so our Goldilocks Zone is far from its surface.

That means Earth is comparatively long way from these solar events. Also, our planet’s powerful magnetic field shields us from these intense and life ending solar events.

But, planets orbiting red dwarfs in close vicinity are vulnerable to stellar radiations, even a magnetic field probably won’t be enough defence.

Scientists have observed lot of red dwarf flares but the data for CMEs from the red dwarfs is inadequate. Without solid evidence, candidate CMEs spotted in red dwarfs could still be flares.

In our Solar System when Sun emits CMEs, usually at the same time it also releases a radio burst (different than fast radio bursts). These radio bursts could suggest CME activity. But not many solar like radio bursts have been detected from red dwarfs.

So scientists looked for more convincing radio bursts evidence from Proxima Centauri, by using NASA’s Transiting Exoplanet Survey Satellite (TESS) and various other ground based telescopes.

They observed a flare and a chain of radio bursts occurring on the red dwarf star. The simultaneous observations enabled the scientists to link the two events. The probability that two events were not related is much less than one chance in 128,000.

It may not be the direct evidence of CME on a red dwarf star, but as of now, it sure is the most promising evidence for a solar like radio burst from a star other than Sun. It seems pretty consistent with a CME, based on the characteristics of solar radio bursts.

According to scientists, that’s probably a bad news in terms of space weather. Red dwarfs are the most common stars in our galaxy, and they won’t be a promising target to look for life as we know it.

In the past ten years or so there has been a huge spike in discovery of exoplanets outside our Solar System, with more than four thousand known exoplanets so far. This has raised the ambitions of scientists to find exoplanets with Earth like conditions.

A recent study suggests that about half the Sun like stars in our Milky Way galaxy could host Earth like exoplanets, but the thing is these stars only make up to seven percent of all stellar objects in our galaxy.

But red dwarf stars like Proxima Centauri make up about seventy percent of stars in Milky Way. And the study results strongly suggest that the intense stellar radiations from these stars has the potential of wiping out any life on exoplanets orbiting it.

For more details: A Flare-type IV Burst Event from Proxima Centauri and Implications for Space Weather

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