“The UV limits of life on extrasolar planets. An experiment with halophile archeabacteria at different UV doses”

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

San Juan, Argentina

Congreso; 51a Reunión de la Asociación Argentina de Astronomía; 2008

<!-- /* Font Definitions */ @font-face {font-family:Calibri; mso-font-alt:"Century Gothic"; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman"; mso-fareast-language:EN-US;} pre {margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Courier New"; mso-fareast-font-family:"Times New Roman"; color:black;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Terrestial-type planets around M stars are proposed as feasible places for development of life as we know it. Nevertheless many dMe stars emit large amounts of UV radiation during flares and it´s unknown if these events could be deleterious for life. Since terrestrial biological systems are particularly vulnerable to this kind of radiation, this fact could set a limit for habitability.Organisms as halophile archaeabacteria were found in halites and ancient evaporites in Earth. Evaporites have been detected in Martian meteorites, so these organisms are proposed as plausible inhabitants of Mars-like planets or other extrasolar planets. Because these organisms are also relatively UV tolerant, we examine the effect of UV-C on the halophile archaea Natrialba magadii. To this end we irradiated cultures of N. magadii with a 15W Hg UV lamp which emits at 254 nm, and we studied the effect of the UV treatment on the irradiated culture. Results show that these organisms are able to survive at the UV doses tested.