HR Diagrams Derived from the Michigan Spectral Catalogue

The data used for the HR diagrams are taken from a volume prepared by Houk and Cowley (1975) and a second volume prepared by Houk (1978). The absolute magnitudes were taken mainly from the Landolt-Boernstein tables. The graphs provided include HR diagrams for normal stars of quality 1 and 2, and errors in HD magnitudes as a function of p.e. magnitude. The HR diagrams for the 184 normal, quality 1 and 2 stars computed to be within 25 pc and the 4700 stars within 100 pc are shown. Only the general picture is significant since the distance to any particular star is so uncertain. The majority of the HD stars within 25 pc are early G dwarfs, with incompleteness setting in for later types. For HD stars within 100 parsecs, the maximum is at G0 and there is a quite abrupt cutoff at F3, the earlier-type stars mainly being further away than 100 pc.