AIP: “Superflares: less harmful to exoplanets than previously thought”

Ekaterina Ilin, PhD student at AIP, and the team developed a method to locate where on the stars’ surface flares are launched from. We discovered that extremely large flares are launched from near the poles of red dwarf stars, rather than from their equator, as is typically the case on the Sun, said Ilin. Exoplanets that orbit in the same plane as the equator of the star, like the planets in our own solar system, could therefore be largely protected from such superflares, as these are directed upwards or downwards out of the exoplanet system. This could improve the prospects for the habitability of exoplanets around small host stars, which would otherwise be much more endangered by the energetic radiation and particles associated with flares compared to planets in the solar system.

Ekaterina Ilin

Some potential good news for the long-term survival of life around M dwarf stars, the smallest and most numerous in our galaxy – and an additional conundrum for the Red Sky Paradox. The sample size of only four stars is very small though, and there may be other mechanisms affecting the distribution of flares depending on the stellar mass, age, composition, and magnetic field. Flares could also migrate in periodic cycles over the surface of the star, similar to sunspots on our local star, so I think some additional observations on these sample stars would be in order.

Small stars flare actively and expel particles that can alter and evaporate the atmospheres of planets that orbit them. New findings suggest that large superflares prefer to occur at high latitudes, sparing planets that orbit around the stellar equator. Credit: AIP/ J. Fohlmeister

Another recent study I saw examined the alignment between a star’s direction of rotation and the orbital motion of its planets, and found a significant portion of orbital axis were misaligned with the parent star. Moreover, the study uncovered an unexpected preference for nearly perpendicular orbits. Those planets would therefore not be protected from stellar flares originating near the poles, instead crossing right into their path for maximum damage.