Prospects for the Characterization and Confirmation of Transiting Exoplanets via the Rossiter‐McLaughlin Effect

The Rossiter-McLaughlin (RM) effect is the distortion of stellar spectrallines that occurs during eclipses or transits, due to stellar rotation. Weassess the future prospects for using the RM effect to measure the alignment ofplanetary orbits with the spin axes of their parent stars, and to confirmexoplanetary transits. We compute the achievable accuracy for the parameters ofinterest, in general and for the 5 known cases of transiting exoplanets withbright host stars. We determine the requirements for detecting the effects ofdifferential rotation. For transiting planets with small masses or long periods(as will be detected by forthcoming satellite missions), the velocity anomalyproduced by the RM effect can be much larger than the orbital velocity of thestar. For a terrestrial planet in the habitable zone of a Sun-like star foundby the Kepler mission, it will be difficult to use the RM effect to confirmtransits with current instruments, but it still may be easier than measuringthe spectroscopic orbit.Comment: 18 pages, 8 figures, one table. Minor changes. Accepted to ApJ, to appear in the Jan 20, 2007 issue (v655