Presentation #1142 in the session “Open Engagement Session B”.
The recently discovered TOI-700 d is a nearby Earth-sized planet synchronously rotating around an M star in the conservative habitable zone. In order to evaluate the planet’s potential for habitability, we use a three-dimensional climate model to simulate possible habitable states. Our suite of simulations involves both ocean-covered and desiccated planets, with a variety of atmospheric compositions, pressures, and rotation states. We also synthesize transmission spectra, combined-light spectra, and integrated broadband phase curves for our modeled cases. We find that TOI-700 d can potentially maintain temperate surface conditions and liquid water under a wide range of climates, making it a strong candidate for a habitable world. However, the resulting transmission spectra and synthesized phase curves reveal spectral feature depths and peak fluxes that do not exceed 10 ppm, which will prohibit the James Webb Space Telescope from characterizing its atmosphere. This highlights the great challenges the community faces for characterizing potentially habitable worlds that are similar to TOI-700 d. We also discuss future plans to include photochemistry in our climate modeling which can strongly impact both habitability and observed spectral features. Our further understanding of TOI-700 d will make it a valuable point of comparison against other potentially habitable planets around later M dwarfs, such as TRAPPIST-1.