Page 10, The Stars I: [Previous Page] [Next Page] [Lecture Notes] [Class Home Page]

80 years ago, We knew nothing of how the Sun or stars worked.




What properties of stars were known at that time?

• Spectral Classification.

• Relative Brightness.

But-- if they knew distance (via parallax), they knew LUMINOSITY.



For most stars, spectral types (essentially temperature) and LUMINOSITY, were found to be related in a very specific way:







This diagram was to be known as,
The Hertzsprung-Russell Diagram