Stellar flares can be signs of life: space weather affects planetary habitability

Space weather affects exoplanet habitability

The astronomers always believed that one of the signs of life on alien worlds may be the presence of water in its liquid form. The researchers are exploring other potential opportunities for the formation of life forms on distant planets now. They believe that space weather, including stellar flares, can affect the planet's habitability. First of all, the assumption concerns the exoplanets studied by the astronomers.

They revolve around their stars outside the Solar System. Exoplanets, as it turned out, are extremely susceptible to the influence of space weather in the form of stellar flares, as well as stellar emissions.

Radiation consists of photons of extreme ultraviolet photons. The second component in their composition is charged particles capable of changing the upper layer of the exoplanet's atmosphere. None of the modern methods of studying distant exoplanets took stellar activity into account. The experts at the Space Science Center at New York University Abu Dhabi (NYUAD) decided to fill this gap.

The researchers determined what stars are most likely to host habitable exoplanets based on calculated rates of erosion of planetary atmospheres. The astronomers found out that frequent low-energy flares have a significantly greater effect on the exoplanet's atmosphere than frequent high-energy flares.

One of the most important requirements in a potential "Earth" is the ability to maintain the atmosphere. But the new study allows to make a fresh look at the habitability of the exoplanets in conditions of stellar activity.

The astronomers speculate that atmospheric gases that are ejected into space could erode the atmosphere and reduce the planet's habitability. The closer a star is to an exoplanet, the more likely that proximity could affect the exoplanet's habitability.

Reference: “Stellar flares versus luminosity: XUV-induced atmospheric escape and planetary habitability” Monthly Notices of Royal Astronomical Society: Letters. DOI: 10.1093/mnrasl/slaa166