Impact of stellar variability on the atmospheres of Earth-like exoplanets
Similar to the sun's impact on Earth's atmosphere, the charged particles and UV radiation emitted by other stars can also influence the composition of the atmospheres of the planets orbiting them. This effect can be particularly profound - and potentially much more severe than on Earth - for exoplanets that are very close to an active host star, such as planets in the habitable zone of M-stars.
Applying our knowledge of ion-chemistry processes in Earth's atmosphere, we investigate this impact for planets differing from our own in orbital parameters and/or atmospheric composition as well as for a variety of different stellar types (from G to M). Particular focus of our studies are placed on determining how potential biosignatures (atmospheric signatures indicative of life) like ozone could be affected by this interaction between star and planetary atmosphere, and the impact on the observable spectral signatures of the planetary atmospheres.
For this purpose, we have adapted and generalized an ion-chemistry model originally written for Earth's atmosphere and participate in a joint projects with partners at the DLR Institute for Planetary Research in Berlin Adlershof and the Christian Albrechts University of Kiel.
Comparison of planets in the M-star system Trappist-1 and in the solar system. Artists impression courtesy NASA/JPL-Caltech.