Radial Velocity (RV) is the component of velocity of a body on a line between the body and the observer, i.e., the movement toward or away from the observer. A star's radial velocity can be determined by measuring the Doppler Shift of known Spectral Lines (Spectral Radial Velocity), which can be used to identify the presence of Extra Solar Planets and Binary Stars. Observatories with instruments designed to determine radial velocities are sometimes referred to as RV Observatories (Radial Velocity Observatories).
Measuring changes in radial velocity over time is helpful for detecting planets with small (a day or few days) or medium (1-2AU) orbits, but Transits reveal more of the smaller orbits.
Velocity Dispersion (σ)
Double-Line Spectroscopic Binary
Extra Solar Planet
Galactic All-Sky Survey (GASS)
Hot Jupiter (HJ)
Local Standard of Rest (LSR)
Position-Position-Velocity Space (PPV)
Sloan Digital Sky Survey (SDSS)
Stellar Mass Determination
Telescopio Nazionale Galileo (TNG)