Astrospheric shielding of habitable planets

• Applicant: Dr. Klaus Scherer
• Subject Area: Astrophysics and Astronomy
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 491027218

The top of the atmosphere of an exo-planet in a habitable zone is hit by a galactic comic flux as well as a flux of neutral hydrogenatoms. These fluxes can change the composition of the atmosphere and therefore also possible bio signatures, like ozone or methane. The flux of the galactic cosmic rays as well as that of the neutral hydrogen atoms from the interstellar medium is strongly influenced by an astrosphere. The astrosphere is the region, in which the super fast-magnetsonic stellar wind expands and finally at the boundary to the interstellar medium a shock structure is created. Because the stellar wind as well as the interstellar medium have a magnetic field, a 3D simulation of the astrosphere is required. Also the modulation of the comic rays needs to be modeled with a 3D simulation, because the diffusion tensor depends on all three space dimensions.In this project the 3D structure of the astrosphere shall be modeled. The symmetry of the astrosphere depends on the orientation ofthe interstellar magnetic field, which will be varied in 45 degree steps to determine the influence of the orientation of the interstellar magnetic field. In addition different stars, which have exo-planets in the habitable zone, with different winds and interstellar environments will be modeled. From that models the flux of the neutral hydrogen can be determined directly at the position of the planet, while the cosmic ray flux will modeled with a 3D transport code by E. Engelbrecht using the 3D astrosphere models.The goal of the project is to determine the cosmic ray and neutral hydrogen flux at the top of an exo-planetary atmosphere and to find asimple formula to describe these fluxes.

• DFG Programme: Research Grants
• International Connection: South Africa
• Cooperation Partners: Professor Dr. Eugene N. Engelbrecht, Ph.D.; Professor Dr. Stefan Ferreira, Ph.D.
• Co-Investigators: Privatdozent Dr. Horst Fichtner; Privatdozent Dr. Konstantin Herbst, Ph.D.