DIX Planetary Science Seminar

Tuesday, October 11, 2022
4:00pm to 5:00pm
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Arms 155 (Robert P. Sharp Lecture Hall)
From the Glactic to Atomic Scale: Understanding Planet Formation and Evolution
Akash Gupta, Graduate Student, Earth, Planetary and Space Sciences, UCLA,

One of the most profound findings from NASA's Kepler mission is the unexpected dearth of close-in exoplanets of sizes 1.5 to 2.0 Earth radii, i.e., a radius valley. This valley divides the population of the most abundant class of planets yet known, those between the sizes of Earth and Neptune, into small planets with Earth-like compositions and large planets with hydrogen-rich atmospheres or ice-rich interiors. Recently, we demonstrated that atmospheric mass-loss driven by the cooling luminosity of a planet and its host star's bolometric luminosity can explain this observation, even in the absence of any other process. In this talk, I will describe the key physical processes that drive this core-powered mass-loss mechanism. I will present how our results compare with observations, the insights they give us and the testable predictions we make as a function of planet and host-star properties. This will include sharing our latest work on the characteristics of the radius valley around M dwarfs.

One of our significant findings is that most observed exoplanets have hydrogen atmospheres interacting with molten or super-critical interiors for millions to billions of years. In our Solar system, we see this for planets such as Jupiter and Neptune. Studies show that such interactions can have far-reaching implications for an atmosphere's composition, structure, and evolution. However, we hardly understand these interactions, and studying them in a laboratory is difficult. I will discuss how we address this problem using quantum mechanical molecular dynamics. Specifically, I will share the findings of our upcoming work on the solubility of a planet's hydrogen atmosphere in its super-critical water interior and their implications for planets and exoplanets such as Neptune.

For more information, please contact Ryleigh Davis by email at [email protected].