Abstract:
The project aims at determining the effects of the high-energy (X-ray) emission from normal stars on the evolution of planetary atmospheres and thus, ultimately, on the establishment of the conditions necessary for the development of life. The mechanisms involved in the interaction between X-rays and planetary atmospheres are complex, producing global effects on the atmosphere's ionization and chemical equilibrium. Depending on the atmosphere's conditions secondary infrared and UV emission will be produced, and in some cases a biologically significant dose of soft UV radiation can reach the ground even for atmospheres that are optically thick to the external incident ionizing radiation. Therefore the study of the effects of stellar activity on planets, at the end affecting planet "habitability" and biological development, is crucial. Such a broad problem requires a wide range of competences and a multi-disciplinary approach. We will activate four fellowships in the following research areas: i) chacterization of the stellar hard X-ray emission and evolution of flare frequency; ii) characterization of the properties, and specifically of X-ray emission, of stellar population in the exo-planet search field for the Eddington mission; iii) physics and chemistry of planetary atmospheres, including their ionization and excitation equilibrium when irradiated with high-energy photons. The scientific output of this project will have an impact on a wide context: on the studies of the history of conditions of the Earth atmosphere (and its climate) and of the other planets of the solar system, of the conditions and evolution of the exo-planets, and of the effects of high energy radiation on the development of life. The project's scientific outcome will be very valuable for chemists and biologists that study the origin of life.