The rossiter-McLaughlin effect in exoplanet research

Abstract

The Rossiter-McLaughlin effect occurs during a planet's transit. It provides the main means of measuring the sky-projected spin-orbit angle between a planet's orbital plane and its host star's equatorial plane. Observing the Rossiter-McLaughlin effect is now a near routine procedure. It is an important element in the orbital characterization of transiting exoplanets. Measurements of the spin-orbit angle have revealed a surprising diversity, far from the placid, Kantian, and Laplacian ideals, whereby planets form, and remain, on orbital planes coincident with their star's equator. This chapter will review a short history of the Rossiter-McLaughlin effect, how it is modeled, and will summarize the current state of the field before describing other uses for a spectroscopic transit and alternative methods of measuring the spin-orbit angle.