JavaScript+HTML Hertzsprung-Russell (HR) Diagram for stars

Allen's Astrophysical Quantities star symbols linked to representative stellar spectra from Perry Berlind's FAST Spectral Atlas at (CfA) - used with permission

ishort "at"

Main Sequence (Dwarfs, V) Red Giants (RGB, III) Supergiants (I) Bright 20 Near 17

Data source:
Allen's Astrophysical Quantities 4thEd,. with links to spectra (displayed below)
Modern Astrophysics (Carroll & Ostlie) 2ndEd., with MS Mass-Luminosity relation