Rossiter-McLaughlin Effect

Rossiter-McLaughlin effect: the observer alternately sees different intensities of a Doppler shift when the star is obscured by a close companion.

The Rossiter-McLaughlin effect is a phenomenon named after the astronomers Richard Alfred Rossiter and Dean Benjamin McLaughlin , by means of which the presence of a binary star system or an extrasolar planet can be detected by means of spectroscopy .

The basic idea here is that Doppler effects can be detected in a star whose equator can be seen from Earth . The side of the equator moving towards the observer shows a blue shift , the other a red shift . When the star is covered by a close companion, the intensity of the blue- and red-shifted part changes alternately. This enables the orbit time, the orbit inclination and the size of the companion to be calculated .

Web links

• Yasuhiro Ohta, Atsushi Taruya & Yasushi Suto: The Rossiter-McLaughlin Effect and Analytic Radial Velocity Curves for Transiting Extrasolar Planetary Systems ; ApJ, v. 622, part 1 (2005), pp. 1118-1135

• Yasushi Suto, Y.Ohta & A.Taruya The Rossiter-McLaughlin effect of transiting extrasolar planetary systems (PDF file; 422 kB) Theory and data for HD209458 - Script for IAU 9th Asian-Pacif Regional Meeting 2005 (engl.)