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(CNN) – One of the planets orbiting Proxima Centauri, the closest star to our sun, was thought to exist within what astronomers call the habitable zone.
While Proxima b is 20 times closer to its star than Earth is to the sun, it receives a similar amount of energy (heat and light) as Earth is from the sun because Proxima Centauri is a cooler and smaller star.
This places the planet in the so-called “Goldilocks zone” of neither too hot nor too cold for any form of life to exist. That means it is believed to have a possible surface temperature range in which liquid water could exist on the planet’s surface. Scientists equate liquid water with life on Earth, and it has also informed their search for life beyond it.
However, new research has daunted hopes that any hint of life may exist on its surface, and the planet is likely experiencing inhospitable space weather.
A team of Australian researchers has for the first time demonstrated a definitive link between optical flares and radio bursts in a star other than the sun. The finding, according to the study published Wednesday in The Astrophysical Journal, was an important step in using radio signals from distant stars to help understand the dramatic effects of space weather on solar systems beyond our own.
“Our own Sun regularly emits hot clouds of ionized particles during what we call ‘coronal mass ejections.’ But since the Sun is much hotter than Proxima Centauri and other red dwarf stars, our ‘habitable zone’ is far from the Sun’s surface, which means that Earth is relatively far from these events, “said lead author Andrew. Zic, who undertook the research while at the University of Sydney, in a press release.
Coronal mass ejections are highly energetic ejections of ionized plasma and radiation exiting the stellar atmosphere.
“Earth has a very powerful planetary magnetic field that protects us from these intense bursts of solar plasma. But since Proxima Centauri is a small cool red dwarf star, it means that this habitable zone is very close to the star; much closer in of what Mercury is to our Sun, “said Zic, who is now a postdoctoral researcher at Macquarie University.
“What our research shows is that this makes the planets very vulnerable to dangerous ionizing radiation that could effectively sterilize them.”
The findings strongly suggest that the planets around this type of star are likely to be covered in stellar flares and plasma ejections and may undergo strong atmospheric erosion, leaving them exposed to very intense X-rays and ultraviolet radiation.
It was possible, Zic said, that radio bursts could occur for different reasons than in the sun, where they are generally associated with coronal mass ejections. But “the probability that the observed solar flare and the radio signal received from our neighbor were not connected is much less than one possibility in 128,000,” he said.
“This is probably bad news on the space weather front. It seems likely that the most common stars in the galaxy, the red dwarfs, are not good places to find life as we know it,” Zic added.
However, Zic said it was theoretically possible that exoplanets – planets outside our solar system – could have magnetic fields like Earth’s.
Observations of magnetic fields around exoplanets have not yet been made, according to the statement, and finding them could be tricky.
“Even if there were magnetic fields, given the stellar proximity of the habitable zone planets around the M dwarf stars, this might not be enough to protect them,” Zic said.
Proxima b was first found by astronomers in 2016 and its existence was confirmed again this year. It is one of approximately 4,000 exoplanets that have been detected since the 1990s.
The Proxima Centauri observations were made with CSIRO’s Australian Square Kilometer Array Pathfinder (ASKAP) telescope in Western Australia, the Zadko Telescope at the University of Western Australia, and other instruments.
This story was first published on CNN.com. Observations of our closest neighboring star lower hopes for a potentially habitable planet
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