On the star closest to the Sun, Proxima Centauri, eruptions a hundred times as powerful as the Sun’s strongest could be common. Such an “insanely large” eruption was observed by five different instruments two years ago, as the responsible researchers explain. The analysis of this immense outbreak could also have consequences for the search for extraterrestrial life, they say. The eruption lasted only seven seconds, but made the star 14,000 times brighter in the ultraviolet spectrum. In order to survive that, life would have to look very different there than on earth.
Observations in many spectra
After powerful eruptions had previously been observed at the star, which is only four light-years away, the researchers working with Meredith MacGregor from the University of Colorado aimed nine different telescopes simultaneously at Proxima Centauri for a total of 40 hours. These included the Hubble Space Telescope, the giant ALMA (Atacama Large Millimeter / submillimeter Array) from the European Southern Observatory (ESO) and even the exoplanet hunter TESS (Transiting Exoplanet Survey Satellite) from NASA. Five of them could have observed the massive outbreak on May 1, 2019, and so a whole range of spectra came together. The study is now published in the Astrophysical Journal Letters presented.
The outbreak was therefore not recognizable in visible light, but mainly in the UV and radio spectrum. All in all, the eruption was about win hundred times as strong as the strongest in the sun. Over time, such eruptions could blow away a planet’s atmosphere, exposing possible life forms to deadly radiation, the statement said. Proxima Centauri exoplanets – two of which have been discovered so far – would not be exposed to such an eruption once a century, but at least once a day or even several times a day. Other outbreaks have also been observed and the team believes further surprises are possible.
Difficult conditions for planets
As the star closest to the Sun, Proxima Centauri has long been a preferred destination for astronomy. As a red dwarf star, it belongs to the most common class of stars in the Milky Way by far. But red dwarfs are also particularly active, the researchers now explain. That doesn’t bode well for exoplanets there. “If there is life on the planet that orbits Proxima Centauri most closely, it would have to look very different from everything we know of the earth,” MacGregor classifies the knowledge: “It would be pretty difficult for a person on this planet.” Proxima Centauri was last in the spotlight in December when a mysterious signal was discovered there that is currently being analyzed.