THE EXO-UV PROJECT: CHARACTERIZATION OF UV RADIATION ENVIRONMENTS AND HABITABILITY OF EXTRASOLAR PLANETS

ABREVAYA, X.C.; LEITZINGER, M.; ODERT, P.; PATEL, M.; GREIMEL, R; NUÑEZ PÖLCHER, P.N.; HANSLMEIER, A.

Chicago

Conferencia; Astrobiology Science Conference 2015 (2015); 2015

The study of the conditions involvedin planetary habitability is one of the maingoals in the Astrobiology field. Among the factors tobe considered, stellar radiation has an essential role inhabitability and their effects can rely at multiple levels,since the radiation received from the parent star caninfluence planetary evolution, atmosphere, and candetermine the origin, evolution and existence of life ina planetary body. The effects of radiation can be beneficialor detrimental depending mainly on the wavelengthand flux of radiation, or in the case of life, thiswill also depend on the mechanisms of life forms tocope with these levels of radiation. In particular, radiationemissions related to UV wavelengths can be aconstraint for life but it has also been postulated as adriving force for biological evolution. Moreover, UVradiation can play a role in photochemical reactionsthat are produced at atmospheric level and could act asan energy source for polymerization/destruction ofprebiotic molecules. Several works have analyzed theinfluence UV radiation fluxes in F, G, K, and M starsin order to determine their suitability for life (e.g: [1],[2]). However, most of the works are theoretical and itwould be necessary to perform laboratory simulationexperiments to test the theoretical predictions that havebeen made. Additionally, there is a lack of data aboutradiation emission fluxes in different stellar astrophysicalcontexts considering particular planetary and atmosphericconditions. The main objective of this projectis to study and characterize radiation environmentsof F, G, K and M stars in the context of exoplanets(Earth-like planets) and to determine if these environmentswould support life, since radiation can act as alimiting factor for the development and evolution oflife. In particular this project has several goals: 1) Thedevelopment of software that allows to obtain correctedUV flux values from data belonging to differentmain sequence stars (F,G,K,M), using as data sourcemeasurements made by the International UltravioletExplorer (IUE) and the Hubble Space Telescope(HST), served by the MAST archive. The aforementioneddata sources provide spectral data that, once corrected for several parameters, allows a good estimationof the UV flux a planet would receive. This willinclude fluxes on the quiescent state of the star but itcould also be expanded to the analysis of flares insome of these stars. 2) The modelling of the atmospheresconsidering the atmospheric features of theplanets to obtain the UV fluxes over the surface of theexoplanets. 3) The simulation of these radiation environmentsunder laboratory conditions (ground basedsimulation experiments) to conduct biological experimentswith microorganisms (UV, 200-400nm range),in particular radiation resistant microorganisms [3,4].This project seeks to expand previous work, consideringsignificant amount of data and laboratory simulationsof these extraterrestrial environments. Therefore,the aim of this project is to provide some importantinsights about planetary habitability, increasing theknowledge about the effects of radiation in the contextof exoplanets and its influence on life, consideringhabitable stars of different spectral types.