A recent discovery links stellar flares with radio-burst signatures — enabling astronomers to more easily evaluate space weather surrounding nearby stars beyond our solar system.
Sadly, initial weather reports from the closest star — Proxima Centauri — are rather grim for life as we've come to know it, according to a recent study published in the journal The Astrophysical Journal.
Bad space weather places 'habitable planets' at risk
"Astronomers have recently found there are two 'Earth-like' rocky planets around Proxima Centauri, one within the 'habitable zone' where any water could be in liquid form," said the University of Sydney's Andrew Zic, Phys.org reports.
Proxima Centauri is roughly 4.2 light-years from Earth.
"But given Proxima Centauri is a cool, small red-dwarf star, it means this habitable zone is very close to the star; much closer in than Mercury is to our sun," added Zic.
"What our research shows is that this makes the planets very vulnerable to dangerous ionizing radiation that could effectively sterilize the planets," Zic explained.
Radio bursts linked to space weather on other stars
The team of astronomers — under Zic's leadership — proved for the first time a distinctive link between optical flares and radio bursts on a star other than our sun. The new finding represents a major step toward using radio signals from distant stars to manufacture space weather reports.
"Our own sun regularly emits hot clouds of ionized particles during what we call 'coronal mass ejections,'" Zic said. "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," added Zic.
M-dwarf radio bursts likely signals bad space weather
This latest research was a collaborative effort with the University of Western Australia, CSIRO, the University of Wisconsin-Milwaukee, Curtin University, and the University of Colorado. Additional efforts from the University of California Berkeley, along with the ARC Centre for Gravitational Waves, were also made.
This study is also integral to Zic's doctoral studies at the Sydney Institute for Astronomy — where Professor Tara Murphy, deputy head at the school of physics of the University of Sydney, supervises.
Zic said: "M-dwarf radio bursts might happen for different reasons than on the sun, where they are usually associated with coronal mass ejections. But it's highly likely that there are similar events associated with the stellar flares and radio bursts we have seen in this study."
Coronal mass ejections spell doom for nearby life
When stars have coronal mass ejections, they send colossally energetic expulsions of ionized plasma — and radiation — out into the stellar atmosphere, and their planetary system.
"This is probably bad news on the space weather front. It seems likely that the galaxy's most common stars — red dwarfs — won't be great places to find life as we know it," said Zic.
Most Milky Way planets orbit red dwarfs, less habitable
In the last decade, a renaissance has surrounded the discovery of planets orbiting stars beyond our own. As of writing, there are more than 4,000 known exoplanets.
However, since sun-like stars only make up roughly 7% of the Milky Way's stellar objects, the majority of exoplanets are more likely to orbit M-type red dwarfs, which make up roughly 70% of the stars in our galaxy — in which case the local space weather might make life as we know it untenable.