Hipparcos Hertzsprung-Russell Diagrams
The Hertzsprung-Russell (HR) diagram is a two-dimensional plot of the luminosity of a star versus its colour. It is a valuable diagnostic tool for astronomers. For the Hipparcos stars this is plotted as luminosity (M_Hp or M_V) versus colour index (B-V or V-I). Each region of the HR diagram represents certain properties of the star, including its evolutionary stage. These figures are examples of the many statistics available from the Hipparcos and Tycho Catalogues (on CD-ROM, in the printed catalogues and on this website).
 
Hertzsprung-Russell (M_V, B-V) diagram for the 4902 single stars from the Hipparcos Catalogue with relative distance precision sigma_pi/pi < 0.05 and sigma_(B-V) less than or equal to 0.025 mag. Colours indicate number of stars in a cell of 0.01 mag in (B-V) and 0.05 mag in V magnitude (M_V). Hertzsprung-Russell (M_V, B-V) diagram for the 16631 single stars from the Hipparcos Catalogue with relative distance precision sigma_pi/pi < 0.1 and sigma_(B-V) less than or equal to 0.025 mag. Colours indicate number of stars in a cell of 0.01 mag in (B-V) and 0.05 mag in V magnitude (M_V). Hertzsprung-Russell (M_V, B-V) diagram for the 41704 single stars from the Hipparcos Catalogue with relative distance precision sigma_pi/pi < 0.2 and sigma_(B-V) less than or equal to 0.05 mag. Colours indicate number of stars in a cell of 0.01 mag in (B-V) and 0.05 mag in V magnitude (M_V).
     
Hertzsprung-Russell (M_Hp, V-I) diagram for the 41453 single stars from the Hipparcos Catalogue with relative distance precision sigma_pi/pi < 0.2 and sigma_(V-I) less than or equal to 0.05 mag. Colours indicate number of stars in a cell of 0.01 mag in (V-I) and 0.05 mag in Hp magnitude (M_Hp). Fraction of stars that are variable in the Hertzsprung-Russell (M_Hp, V-I) diagram. In each cell of 0.03 mag in (V-I) and 0.15 mag in M_Hp, the percentage of variable stars is coded according to the colour scale. Hertzsprung-Russell (M_Hp, V-I) diagram for single stars from the Hipparcos Catalogue with coarse variability indicator non-blank, and with relative distance precision 0.6 mag, 48 stars) = red.