#Radial velocity astrometry full#

Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. The relation between kinematics and the HRD is nicely illustrated. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. Many fine structures of the HRDs are presented. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. Instead, we have chosen several illustrative examples. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD).

The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented.

#Radial velocity astrometry full#

Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky.