UV habitability and dM stars: an approach for evaluation of biological survival.

ABREVAYA X. C.; EDUARDO CORTON; MAUAS P. J. D.

Proceedings of the International Astronomical Union

International Astronomical Union

Año: 2009 vol. 5 p. 443 - 445

1743-9213

Dwarf M stars comprise about 75 percent of all stars in the galaxy. For severalyears planets orbiting M stars have been discarded as suitable places for development of life.This paradigm now has changed and terrestrial-type planets within liquid-water habitable zones(LW-HZ) around M stars are reconsidered as possible hosts for life as we know it. Nevertheless,large amount of UV radiation is emitted during °ares by this stars, and it is uncertain howthese events could a®ect biological systems. In particular UV-C (¸ < 290nm) exhibits the mostdamaging e®ects for living organisms. To analyze the hypothesis that UV could set a limit forthe development of extraterrestrial life, we studied the e®ect of UV-C treatment on halophilearchaea cultures. Halophile archaea are extremophile organisms, they are exposed to intensesolar UV radiation in their natural environment so they are generally regarded as relativelyUV tolerant. Halophiles inhabits in hipersaline environments as salt lakes but also have beenfound in ancient salt deposits as halites and evaporites on Earth. Since evaporites have beendetected in Martian meteorites, these organisms are proposed as plausible inhabitants of Mars-like planets. Our preliminary results show that even after UV damage, the surviving cells wereable to resume growth with nearly normal kinetics.