Home → Exoplanets FAQ → What is the Rossiter-McLaughlin effect?
More and more exoplanet systems are turning out to have a so-called “spin-orbit” misalignment. Such a misalignment places severe constraints on the physical history of the system (formation, perturbation, and planet migration in particular). The angle between the plane containing a planetary orbit and the plane perpendicular to the spin axis of the host star is not to be confused with the inclination angle of the system (the latter measures the angle between the plane of a planetary orbit and the observer's sight line). The spin-orbit misalignment is most quantifiable for transiting planets, using something called the Rossiter-McLaughlin effect, which refers to particular Doppler distortions and modulations to signals received from a spinning object. (Advanced readers: see for example Ohta et al. 2005, which has a comprehensive exposition with historical references.)
Learn more about exoplanets with Exoplanets and Alien Solar Systems.
File under: Definition of the Rossiter-McLaughlin Effect. Spin-orbit Misalignment in exoplanet systems.