Exoplanet by radial velocity and spectra

In this exercise, we explain how an exoplanet orbiting a star can be detected using a precise measurement of the star’s velocity. The radial velocity method takes into account the fact that the planet and the star are both orbiting the centre of mass of the system under study. The aim is to measure variations in the radial velocity of the star relative to the observer as it approaches or recedes from the Earth. The radial velocity can be deduced from the displacement of the lines in the star’s spectra.