Radiation transport in dense hydrogen plasmas at conditions relevant to the interiors of Red Dwarfs

• Applicant: Professor Dr. Dominik Kraus
• Subject Area: Astrophysics and Astronomy ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 495324226

Red Dwarfs are the most common stars in our galaxy and many of them are orbited by exoplanets. Due to convection inside the Red Dwarfs, strong magnetic fields are created, which cause radiation and plasma outbreaks and thus threaten possible life on the surface of the exoplanets. Furthermore, the Red Dwarf stars can get very old by refueling the core via convection. The extent to which convection occurs inside stars depends on how efficiently the radiative energy transport is hindered by absorption. Differently to our sun, the radiation transport deep inside Red Dwarfs is dominated by inverse bremsstrahlung (free-free opacity). The adequate physical description of this process is extremely complex due to the extreme density and relatively moderate temperature of the plasma state. For this reason, current models show strong deviations in their predictions. The main aim of the proposed project will be measuring the absorption coefficient by inverse bremsstrahlung in the laboratory for the first time under conditions that correspond to the deep interior of Red Dwarfs. These elaborate experiments will test current theories of inverse bremsstrahlung in dense plasmas and in turn constrain the mass below which Red Dwarfs become fully convective in their interior. The experimental results will thus also help to better understand the behavior of Red Dwarfs on their surfaces. The latter is decisive as to whether exoplanets can exhibit life-friendly conditions in such star systems.

• DFG Programme: Research Grants
• International Connection: France, USA
• Cooperation Partners: Dr. Mandy Bethkenhagen; Dr. Tilo Döppner