Contributed Talk - Splinter Exoplanets

Friday, 15 September 2023, 17:30   (H 3007)

Investigation of the Influence of Stellar Particle Events and Galactic Cosmic Rays on the Atmosphere of TRAPPIST-1e

Andreas Bartenschlager, Miriam Sinnhuber, John Lee Grenfell, Nicolas Iro, Ben Taysum, Fabian Wunderlich, Konstantin Herbst
Karlsruhe Institute of Technology (Germany), Karlsruhe Institute of Technology (Germany), German Aerospace Center Berlin (Germany), German Aerospace Center Berlin (Germany), German Aerospace Center Berlin (Germany), German Aerospace Center Berlin (Germany), University of Kiel (Germany)

The launch of the James Webb Space Telescope (JWST) in December 2021 opens up the possibility of studying the composition of exoplanetary atmospheres in habitable zones, such as TRAPPIST-1e, in the near future. With the help of numerical models of the exoplanetary atmospheres, the observations and the processes behind them can be better understood and interpreted (Herbst et al., 2022). We investigate the influence of stellar energetic particles (SEPs) on the atmospheric composition of exoplanets around the very active M-star TRAPPIST-1 using the ion chemistry model ExoTIC. In collaboration with the University of Kiel and DLR Berlin, we perform model experiments with different N2 or CO2-dominated atmospheres, depending on the initial CO2 partial pressure, as well as humid and dry conditions (Wunderlich et al., 2020), taking into account the ionization rates for realistic, strong stellar particle events. A further specification is the distinction between dead and alive atmospheres, whose atmospheric composition is characterized by a lower or higher oxygen fraction in the initial conditions. Within ExoTIC we can calculate the impact of the ionization events on these atmospheres both for a very strong single event and for a series of events with different strengths and frequencies, based on the observed flaring frequency of TRAPPIST-1. Results show a significant impact of SEP events on the chemical composition of the atmosphere, including biosignatures such as O3. These changes also have an impact on the transmission spectra observed by JWST. The strength and structure of these impacts depend on the composition of the starting atmosphere, in particular on the availability of oxygen as well as N2 and water vapor.