ACKS Seminar by John Johnson (Caltech)

The Golden Age of Exoplanet Spin-Orbit Measurements

The angular momentum of the Solar System planets is remarkably well aligned with the spin axis of the Sun. This arrangement supports the hypothesis that the planets and the Sun formed from the same spinning disk of gas and dust. Until very recently, measurement of the spin-orbit alignment of exoplanets had revealed that planets around other stars, most in very close-in orbits, also have well-aligned spin and orbit axes. However, our recent measurements from this past year have revealed that there may be a second class of exoplanets that inhabit very tilted orbits, and that some may even have retrograde configurations. I'll show how spin-orbit measurements are made, and discuss how the distribution of observed spin-orbit angles informs, and challenges, theories of planet migration.