The Rossiter-McLaughlin eﬀect for exoplanets

J.N Winn

doi:10.1051/epjconf/20101105002

Abstract

There are now more than 30 stars with transiting planets for which the stellar obliquity—or more precisely its sky projection—has been measured, via the eponymous eﬀect of Rossiter and McLaughlin. The history of these measurements is intriguing. For 8 years a case was gradually building that the orbits of hot Jupiters are always well-aligned with the rotation of their parent stars. Then in a sudden reversal, many misaligned systems were found, and it now seems that even retrograde systems are not uncommon. I review the measurement technique underlying these discoveries, the patterns that have emerged from the data, and the implications for theories of planet formation and migration.

Highlights

When was the first announcement of the detection of a planetary transit? About 10 years ago, the transits of HD 209458b were reported by two different groups (Henry et al 2000, Charbonneau et al 2000)
In 1611, Christoph Scheiner reported the detection of a system of close-in planets transiting the Sun
More recent measurements have revealed a diversity of orbits, including some that are very well-aligned with the equatorial planes of their parent stars, some that are misaligned by more than 30◦, and even some that are apparently retrograde

Summary

Introduction

When was the first announcement of the detection of a planetary transit? About 10 years ago, the transits of HD 209458b were reported by two different groups (Henry et al 2000, Charbonneau et al 2000). For close-in planets, there are various “migration” scenarios for bringing the planets inward from beyond the snow line, which make differing predictions about spin-orbit alignment. More recent measurements have revealed a diversity of orbits, including some that are very well-aligned with the equatorial planes of their parent stars, some that are misaligned by more than 30◦, and even some that are apparently retrograde.

Results

Conclusion