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Dix Planetary Science Seminar

Tuesday, March 10, 2020
4:00pm to 5:00pm
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South Mudd 365
Neptune viewed with the VLA, ALMA, and whatever comes next
Joshua Tollefson, Post Doc, UC Berkeley,

Abstract: The compositions of planets are tied to their formation history and the planetary nebula from which they formed, as well as their interior structure and dynamics. More than 30 years ago, Voyager flew by the ice giants and reasonably constrained H2 , He, and carbon enrichment on both Uranus and Neptune. Since then, ground-based telescopes have been our main resource for studying these bodies. These observations combined with radiative transfer modeling help constrain the abundance of other elements (S, O, N, P) that are sequestered in other molecules (e.g., H2S, H2O, NH3, PH3). However, these molecules condense deep in the atmosphere making them difficult to directly observe. In this talk, I will present spatially-resolved radio observations of Neptune taken with the Very Large Array (VLA) and Atacama Large Submillimeter/Millimeter Array (ALMA). The radio probes below the main methane cloud deck and haze, allowing H2S and NH3 profiles to be retrieved. I show new results on the globally-varying abundance profiles of these trace gases and compare these trends to recent observations in the near-infrared and optical. From this, a picture of the structure and dynamics of Neptune's upper atmosphere is constructed. The next generation of radio astronomy, whether be with an expanded VLA or direct mission to the ice giants, will be critical for advancing our understanding of these planets.

For more information, please contact Shreyas Vissapragada by email at [email protected].