Stellar spectroscopic surveys: overview, expectations and achievements

Abstract : Multi-fibre spectrographs have made possible the run of large spectroscopic surveys targeting 10^5 to millions of Milky Way (MW) stars. The targeted stars belong to the main stellar structures of our Galaxy and mostly sample stellar evolutionary stages from the (pre-)main-sequence to the red giant branch. Their primary aim is to harvest a vast amount of data (radial velocities, stellar parameters, abundances) in order to constrain the formation and evolution of the MW. We will focus on two spectroscopic surveys France is involved in. First, we will briefly introduce the WEAVE spectroscopic survey, that will soon start to observe at the William Herschel Telescope, and show from simulations what can be expected in terms of chemical abundances. Second, we will highlight the relevance and usefulness of such large project by reminding some of the results obtained within the Gaia-ESO survey.