Wolf Prize Laureate in Physics 2017
Affiliation at the time of the award:
University of Geneva, Switzerland
University of Cambridge, UK
“For the first discovery of an exoplanet orbiting a solar-type star”.
In 1995, Mayor and Queloz were the first to discover a planet outside the solar system orbiting a solar-type star. The discovery of this planet, 51 Pegasi b, was the result of a continuous improvement of cross-correlation spectrographs by Mayor (completed in collaboration with Queloz) over a period of 20 years in order to obtain more accurate radial velocities. The discovery of 51 Pegasi b led to a revolution in the theory of planetary systems, since it is a Jovian planet having a very short orbital period of only 4.2 days, orders of magnitude smaller than the 12-year period of Jupiter in the solar system. This short period is attributed to orbital migration of planets during their formation in an accretion disk.
This discovery opened the floodgates for subsequent observations revealing an incredible diversity of exoplanets, some with large and quite eccentric elliptical orbits, unlike the nearly circular orbits in our own solar system. The team led by Mayor and Queloz has contributed to the discovery of more than 250 additional exoplanets, including several multi-planetary systems having up to 7 planets. Thanks to the most recent spectrograph (HARPS) developed by their team and installed at La Silla Observatory, they were able to reveal the very rich subpopulation of super-Earth planets on tight orbits and to conduct statistical research on exoplanets. Mayor participated in the first detection of an exoplanet transiting its host star, opening the way to the study of the composition of exoplanets. Soon after, Queloz, Mayor and their collaborators were able to measure the first Rossiter-McLaughlin effect for a transiting planet, which allowed the measurement of the projected angle between the stellar spin axis and the planets orbital axis. Subsequent observations show a large variety of angles, which cannot be explained solely by planetary migration.