Flares and habitability

ABREVAYA, X. C.; CORTÓN, E.; MAUAS, P.J.D.

Mendoza

Congreso; IAU Symposium 286: Comparative Magnetic Minima: Characterizing quiet times in the Sun and stars; 2011

IAU

At present, dwarf M stars are being considered as potential hosts for habitable planets.However, an important fraction of these stars are flare stars, which among other kind ofradiation, emit large amounts of UV radiation during flares, and it is unknown how this eventscan affect life, since biological systems are particularly vulnerable to UV. In this work we evaluatea well known dMe star, EV Lacertae (GJ 873) as a potential host for the emergence andevolution of life, focusing on the effects of the UV emission associated with flare activity. SinceUV-C is particularly harmful for living organisms, we studied the effect of UV-C radiation onhalophile archaea cultures. The halophile archaea or haloarchaea are extremophile microorganisms,which inhabit in hypersaline environments and which show several mechanisms to copewith UV radiation since they are naturally exposed to intense solar UV radiation on Earth. Toselect the irradiance to be tested, we considered a moderate flare on this star. We obtained themean value for the UV-C irradiance integrating the IUE spectrum in the impulsive phase, andconsidering a hypothetical planet in the center of the liquid water habitability zone. To selectthe irradiation times we took the most frequent duration of flares on this star which is from 9to 27 minutes. Our results show that even after considerable UV damage, the haloarchaeal cellssurvive at the tested doses, showing that this kind of life could survive in a relatively hostileUV environment.