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DIX Planetary Science Seminar

Tuesday, April 6, 2021
4:00pm to 5:00pm
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Online Event
Revealing the Bulk Compositions of Small Planets
Michael Greklek-McKeon, Graduate Student, Planetary Science, California Institute of Technology,

Planets transiting nearby M dwarf stars are the best laboratory we have to study exoplanets with terrestrial sizes, compositions, and insolation levels. Transit surveys indicate that M dwarfs frequently host small planets orbiting in or near the habitable zone, and M dwarfs dominate the population of stars in the local solar neighborhood. However, it is unclear how the properties of small planets orbiting M dwarfs might differ from those of the terrestrial worlds in our own solar system. M dwarf planets could accrete significantly larger amounts of water because the ice line of their host star is closer in, and could be more likely to host massive volatile-rich atmospheres; but they might also be less likely to retain those atmospheres due to the high activity levels of their host star. We can explore the possible formation and evolution histories of these planets by measuring their masses and radii, which we can use to determine bulk densities that reveal the atmospheric mass fraction and possible bulk compositions of the planets. The TESS mission has discovered many dynamically interacting multi-planet M dwarf systems, and even one or two follow-up observations with space-like photometric precision is enough to determine the masses of these planets with transit timing variations (TTVs). I will discuss an example case of using Palomar observations to constrain the masses and bulk densities of planets with TTVs, and then make some predictions about our upcoming observations that will extend this method to small M dwarf planets.

For more information, please contact Aida Behmard by email at [email protected].