Fraction of Stars by Spectral Type in the Solar Vicinity

Pie chart showing the fraction of local stars in the solar vicinity by spectral type, excluding brown dwarfs (L/T/Y dwarfs). Red giants and white dwarfs are treated as separate categories, and the OBA/F/G/K stars include dwarfs and subgiants. Densities were calculated by the author using astrometry and spectral classification data from the Hipparcos & revised Hipparcos catalogs (ESA 1997, van Leeuwen 2007) and RECONS database over volume-limited samples depending on the brightness of members of the individual classes (e.g. F-star sample was calculated using 30 pc Hipparcos sample, whereas M-dwarf sample used 10 pc RECONS sample). No attempt was made to account for unresolved multiplicity for the O/B/A/F and red giant samples (so their densities may be slightly higher), whereas the G/K/M dwarf samples are likely to be approximately complete even accounting for multiplicity.

The local densities of stars by type in units of pc^-3 are approximately: O-type (~1e-7; highly uncertainty), B-type (3.2e-5), A-type (4.9e-4), F-type (2.3e-3), G-type (4.8e-3), K dwarfs (1.05e-2), M dwarfs (5.92e-2), red giants (K/M III or more evolved; 2.7e-4), and white dwarfs (4.8e-3).