Graphite Haze Formation in sub-Neptune Atmospheres within the Graphite-stability Regime

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New space and ground-based telescopes will soon observe planets around other stars and search for signs of life in their atmospheres. The sub-Neptune type of planets are among the observing targets. However, graphite haze is expected to form in many of these sub-Neptunes and can block our observations. A team led by Johns Hopkins University will experimentally explore graphite haze formation in sub-Neptune atmospheres. They will constrain what type of sub-Neptune atmospheres are likely to produce graphite hazes, helping choose future observation targets. They will also measure the graphite’s properties critical for interpreting future observations. The team will conduct K-12 education and public outreach programs. This program will provide research internships for six underrepresented students.This research will make a significant impact on the state of knowledge in the field of exoplanet atmospheric chemistry, and is critical to current and future exoplanet atmospheric characterization efforts. The team will investigate chemical processes occurring in sub-Neptune atmospheres within the graphite-stability regime using a state-of-art laboratory facility specifically designed to investigate a range of planetary atmospheres. They will determine the reaction conditions, compositional alternation, and graphite’s impacts on the detectability of key atmospheric gas spectral features. The specific tasks that the team will perform include: (1) constraining the conditions for the formation of graphite and determine the transition efficiency under those conditions; (2) measuring the gas phase compositions and identify plausible chemical processes for the formation of graphite; (3) Measuring optical properties of the resulted graphite hazes from visible to mid-infrared.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.