Testing Predictions for Spin-Orbit Alignment Among Ensembles of M Dwarf Planetary Systems

The alignment of planetary orbital spin with host star rotational spin is a powerful tool to investigate a system’s dynamical state. When focused upon long-lasting M dwarf stars, and when examined in large ensembles, we can probe patterns among systems that may manifest over timescales of Gyr: are planetary systems orbiting these stars typically well-preserved since birth, or is there evidence for continuous sculpting? We explore a novel technique of stacking radial velocity data for similar planet-star systems to extract average spin-orbit alignment for M dwarfs, for planets typically in the R_p < 4 R_⊕ planet range. We explore how to best compare observed spin-orbit alignments to predictions for the Rossiter-McLaughlin effect, when comparing various configurations of small exoplanets transiting M dwarf host stars.