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A Survey of Atmospheric Escape On Neptune Desert Worlds

Presentation #624.27 in the session Planetary Atmospheres - Hot Jupiters.

Published onApr 03, 2024
A Survey of Atmospheric Escape On Neptune Desert Worlds

Photoevaporative mass loss is thought to play a central role in sculpting the population of close-in exoplanets, and is potentially responsible for the creation of both the ‘evaporation valley’ (a period dependent separation between rocky super-Earths and sub-Neptunes) and the lower boundary of the ‘Neptune desert’ (a deficit of Neptune-sized planets on close-in orbits). For the past few years, we have surveyed atmospheric escape rates for planets on close-in orbits using metastable helium with Keck/NIRSPEC. Here we present new detections of atmospheric mass loss for several representative planets located near the inner edge of the Neptune desert. Our spectroscopically resolved measurements of helium outflows allow us to characterize the outflow temperature and opacity from the line profile, reveal the presence or absence of atmospheric tails by searching for extended absorptions, and detect velocity shifts indicative of a strong planetary magnetic field. We present new outflow detections including one for TOI-1259 A b, marking the first outflow detection for a planet with a white dwarf companion. We place these new detections into context with previous mass loss measurements to provide new insights into the role of atmospheric escape in sculpting the Neptune desert.

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