[LINK] "A Renewed Concern: Flares and Astrobiology"

[rfmcdonald]

Centauri Dreams' Paul Gilster shared the news that red dwarfs--the most common stars in the galaxy, dim stars with only a small fraction of the mass of our dear old Sol--are more prone to dangerous flares

M-dwarfs are by far the most common type of star in the Milky Way, and therefore have major implications for the search for extraterrestrial life. We now know from SWEEPS data that these small stars are given to stellar flares that can have major effects on a planetary atmosphere. Flares have often been mentioned as a serious problem for the development of life on M-dwarf planets, but the new data tell us they may be more dangerous than we had thought, occurring on a regular and frequent basis.

[. . .]

The threat, vividly portrayed in the results presented by Adam Kowalski (University of Washington) at the conference, involves an eruption of hot plasma that happens when magnetic field lines in a stellar atmosphere reconnect and release an amount of energy that can surpass that of 100 million atomic bombs. From the perspective of life on a planet orbiting an M-dwarf, the planetary surface is blasted with ultraviolet light and a bath of X-rays, along with the charged particles of the stellar wind. The SWEEPS study, with observations over a seven-day period, found 100 stellar flares in this largest continuous monitoring of red dwarfs ever undertaken.

[. . . I]t’s not just young, active stars that pose the threat, according to Osten:

“We know that hyperactive young stars produce flares, but this study shows that even in fairly old stars that are several billion years old, flares are a fact of life. Life could be rough for any planets orbiting close enough to these flaring stars. Their heated atmospheres could puff up and might get stripped away.”

Earlier models of planets orbiting red dwarfs I'm familiar with suggested that habitable planets with Earth-like environments could survive, especially given sufficiently strong magnetic fields to deflect charged particles. Anyway, go read, and hope that the red dwarfs' flares aren't that bad.