Caption: A Hertzsprung-Russell (HR) diagram for a large sample of stars. The sample is NOT a large volume-limited one, and so does NOT give the true distribution of stars among the stellar classifications (i.e., spectral type and luminosity classes).
Features:
The high-temperature blue-white stars are on the left and the low-temperature red stars on the right.
So the stars on the plot do NOT reflect the actual relative abundances of stars of each stellar classification as noted in the preamble. If it did show the correct relative abundances, there would be far more stars at the lower end of the main sequence.
Nevertheless, the sample is sufficiently fair that it shows there are relatively few bright giants (luminosity class II) and supergiants (luminosity class I). Though relatively rare such stars are rather conspicuous because of their high luminosity.
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