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TRAPPIST-1c likely formed with less carbon than Earth or Venus

Presentation #410.01 in the session Exoplanet Atmospheres: Terrestrial Planets (Oral Presentation)

Published onOct 23, 2023
TRAPPIST-1c likely formed with less carbon than Earth or Venus

With the successful deployment of JWST, and its aim to potentially search for biosignatures on exoplanets, an important endeavor, at present, is to determine whether the rocky planets we observe are likely to have atmospheres at all. M dwarfs, the main host stars of JWST’s rocky planet targets, are thought to pose a major threat to planetary atmospheres due to their high magnetic activity over several billion-year timescales, and might completely strip atmospheres. Several Cycle 1 GO programs are testing this hypothesis, observing some of the most interesting rocky planets that we know, e.g., the TRAPPIST-1 system. An interesting case-study is TRAPPIST-1c, which receives almost the same bolometric flux as Venus. We might, therefore, expect TRAPPIST-1c to possess a thick, CO2-dominated atmosphere. Instead, recent observations show that TRAPPIST-1c potentially has trace amounts of CO2 in its atmosphere. We need physical models to explain these results, to understand how a planet’s atmosphere evolves to become what we see today. Here, I will present coupled time-dependent simulations of planetary outgassing and atmospheric escape, processes that most influence atmospheric composition, that model the evolution of TRAPPIST-1c’s atmosphere. I will discuss the results of the simulations, specifically the constraints that they place on the history of TRAPPIST-1c’s atmosphere. I will describe the most likely range of planetary properties of TRAPPIST-1c, including initial carbon budget and radiogenic heat element budget, that agree with observations. Finally, I will discuss how this work can be expanded to model different physical phenomena and more potentially habitable planets.

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