Cosmos Seminar: Seeking to Uncover The Obliquities of Small Planets
Jan
23
2025
Jan
23
2025
Description
Seeking to Uncover The Obliquities of Small Planets
The angle between the stellar spin axis and the planet’s orbital planet, the stellar obliquity, is one of the fundamental parameters to understanding a system’s architecture and is itself a probe into the formation, evolution, and dynamical history of the system. However, to date, only ~200 obliquities have been measured via the Rossiter-McLaughlin (RM) effect, ~80% of such which are Hot Jupiters due to physical and observational biases. However, with the newest fleet of extreme precision radial velocity (EPRV) spectrometers, measuring the obliquity of small planets, such as sub-Neptunes, is just now beginning to be possible. We measured the obliquity of HD 191939 b, a typical sub-Neptune in a typical Kepler-like chain of sub-Neptune planets, finding it consistent with alignment. Additionally, we present the early stages of a new data-driven model to measure accurate and precise vsini values for slowly rotating (<3 km/s) stars. Vsini, which itself is a tracer for obliquity in the sky-plane dimension, is unbiased with regard to planet size and this model could open up a large new region of parameter space to measure obliquities of small planets en masse.
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