The First Space Weather Report From Another Star Is Bad News For Life

Artist's impression of a flare from our neighboring star Proxima Centauri ejecting material onto a nearby planet. Mark Myers/OzGrav

Australian researchers report the first detection of solar-like radio bursts from another star. The star in question is the closest to our Sun, Proxima Centauri, and the radio burst was associated with a stellar flare, a dramatic brightening of the star. This first example of a space weather report from another star is exciting but it also has some grim implications for life around these stars.

Proxima Centauri is a red dwarf, much smaller and cooler compared to our Sun. It is orbited by two planets Proxima b, which is Earth-sized and in the habitable zone, and Proxima c, which is a super-Earth orbiting further out.

The habitability of Proxima b has a big question mark on it. One concerning factor is the behavior of the star. Dwarf stars tend to be a lot more active and could end up bombarding a planet with a deadly level of radiation.

The work, published in The Astrophysical Journal, finally shows that Proxima flares just like the Sun. As Proxima b is much closer to the red dwarf than Earth is from our star, this is not good news for the chances of alien life there.

"What our research shows is that this makes the planets very vulnerable to dangerous ionising radiation that could effectively sterilise the planets," lead author Andrew Zic from the University of Sydney, said in a statement.

"Our own Sun regularly emits hot clouds of ionised particles during what we call 'coronal mass ejections'. But given the Sun is much hotter than Proxima Centauri and other red-dwarf stars, our 'habitable zone' is far from the Sun's surface, meaning the Earth is a relatively long way from these events. Further, the Earth has a very powerful planetary magnetic field that shields us from these intense blasts of solar plasma."

It is likely that most radio bursts from dwarf stars are caused by and linked to different phenomena than the radio bursts from the Sun, but seeing such an example provides important insight into these stars as well as telling us something about planetary habitability.

The discovery was possible by doing optical and radio observations of Proxima at the same time. These were conducted with CSIRO's Australian Square Kilometre Array Pathfinder (ASKAP) telescope, NASA's planet-hunting Transiting Exoplanet Survey Satellite, and the Zadko Telescope. The possibility the flare and radio burst were not connected is less than one in 128,000 chances.

This approach to study space weather around distant stars could help us better understand these celestial bodies and possibly even the Sun.


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