Presentation #303.06 in the session “Dark Energy Spectroscopic Instrument (DESI): On Sky”.
The DESI Milky Way Survey (MWS) will observe over 8 million stars between 16<r<19 mag during bright time, in addition to brighter stars (10<r<16 mag) in a backup program for poor observing conditions. In this talk we highlight early results from DESI commissioning and survey validation programs that showcase the potential of MWS. We have verified that stellar radial velocities can be measured by DESI to an accuracy of 5km/s, and stellar parameters to 0.1 dex at r=19. This will allow MWS to characterize diffuse substructure in the Galactic thick disk and stellar halo, discover extremely metal-poor stars and other rare stellar types, and improve constraints on the Galaxy’s 3D dark matter distribution from halo star kinematics. MWS will also enable a detailed characterization of the stellar populations within 100 pc of the Sun. 80 white dwarfs have been discovered in our early data, one of which shows clear signatures of on-going accretion of a tidally disrupted planetesimal. In full operation, DESI will observe roughly 100 white dwarfs per night, building a rich sample from which we will we can derive detailed exoplanet compositions.