Hundred times more than the sun! Proxima Centauri explodes with superflare, which has major impact on alien life

This flare released about 100 times the energy of a solar flare.

Scientists recently confirmed the largest documented stellar flare in the Milky Way. Our Sun's closest neighbor, the red dwarf Proxima Centauri, released a massive jet of plasma through this flare. The flare released 100 times more energy than any that our solar system has ever experienced, and could change the way scientists think about solar radiation and alien life.

Proxima Centauri is a red dwarf star about 4.25 light-years from Earth—the smallest, faintest, and most common type of main-sequence star in the Milky Way. It is only 1/8 the mass of the sun and has two planets orbiting it. One of them, Proxima Centauri b, is thought to be a terrestrial planet and orbits in the habitable zone -- a distance that, according to the researchers, may be suitable for the evolution of life.

In the latest study, researchers used nine ground-based or orbiting telescopes -- including the Hubble Space Telescope, the Atacama Large Millimeter/Submillimeter Array in Chile, and NASA's Transiting Exoplanet Survey Telescope -- to Proxima Centauri was closely monitored for a total of 40 hours over several months in 2019. On May 1, 2019, the team captured this superflare that lasted for 7 seconds, and its main spectrum is in the ultraviolet light band.

"It took only a few seconds for this star to jump from its normal value to 14,000 times its brightness in ultraviolet light," said lead author Meredith MacGregor, an astrophysicist at the University of Colorado Boulder, in said in a statement.

The energy and radiation released by this flare changed our understanding of the probability of life on red dwarf stars and their orbiting planets.

super flare

Stellar flares are caused by the star's strong magnetic field. The process of these magnetic fields—created by a mass of electrically charged gas—twisting together and snapping back into place suddenly produces enormous amounts of energy in the form of radiation, like loosening a rubber band around a finger and shooting someone.

Compared to solar flares, this flare from Proxima Centauri is extremely powerful. Unlike solar flares, it also emits different types of radiation. In particular, it produces enormous amounts of ultraviolet light and radio waves -- often referred to as "millimeter-wave radiation."

Artistic rendering of a stellar flare seen from Proxima Centauri b (Credit: NRAO/S. Dagnello)

"In the past, we didn't know that stars can flare at millimeter wavelengths, so this is the first time we've tracked a millimeter-wave flare," MacGregor said in the statement.

The discovery may simply be due to the team's use of so many different telescopes, each specialized in a certain area of ​​observation of the electromagnetic spectrum.

"This is the first time we've ever used this multi-wavelength coverage to observe a stellar flare," MacGregor said in the statement. "Usually, you're lucky to have two instruments."

The new finding hints that red dwarfs produce far more violent flares than we had previously estimated, while reducing the likelihood of life on planets orbiting such stars.

bad news about alien life

The researchers believe that the type and intensity of radiation emitted by Proxima Centauri this time makes it difficult for planets in its orbit to produce life, because the flares are so violent that it is difficult for a real atmosphere to form on the planet. But it's not entirely impossible for alien life to exist there.

"If life were to exist on the nearest planet to Proxima Centauri, they could be completely different from everything else on Earth," MacGregor said in the statement. "A human being would be fine on that planet."

The researchers believe that other red dwarf stars are likely to produce equally powerful flares, thus reducing the probability of life on planets hosted by red dwarf stars. They also produce flares more frequently than the Sun, which reduces the chances of finding life in such systems to a greater extent.

"The planets of Proxima Centauri are hit not once a century, but at least once a day, if not multiple times a day," MacGregor said in a statement.

Researchers now hope to use multiple types of telescopes to focus on other stellar flare phenomena in the Milky Way.

"There may be other exotic types of flares that can show us different types of physical phenomena we haven't thought of before," MacGregor said in the statement.

related information

Proxima Centauri is a small, low-mass star located 4.2465 light-years (1.3020 parsecs) from the Sun in the southern constellation Centaurus. Its Latin name means "nearest star of the constellation Centaur". Discovered by Robert Innes in 1915, it is the closest known star to the Sun. Because its apparent magnitude is only 11.13, it is basically invisible to the naked eye. Proxima Centauri is a member of the Alpha Centauri triplet, known as Alpha Centauri C, located 2.18 degrees southwest of the Alpha Centauri AB binary system. It is currently 12,950 AU (0.2 light-years) away from the AB binary system and orbits the AB binary system with an orbital period of 550,000 years.

Proxima Centauri is a red dwarf star about 1/8 (12.5%) the mass of the Sun, with an average density of 33 times that of the Sun. Since it is closer to the Earth, its angular radius can be measured directly. Its diameter is about 1/7 (14%) the diameter of the sun. Despite its low average brightness, Proxima Centauri is a flare star, whose brightness increases dramatically from time to time due to magnetic field activity. The star's magnetic field is generated by convection flowing through its interior, and the resulting flare activity generates a large stream of X-rays similar to the Sun's. Convection deep into the core allows for complete mixing of the fusion fuel inside, and the relatively low rate of energy production means it is a main-sequence star with a lifespan of 4 trillion years.