The Electronic Sky
Asteroids, Clusters, Comets, Concepts, Constellations, Galaxies, IC Objects, Messier Objects
Moons, Nebulae, NGC Objects, Planets, Star Clusters, Stars: Proper Names, Stars: Bayer
Stars: Flamsteed, Stars: Others, Surface Features.
Spectroscopic Investigation One important object of this original spectroscopic investigation of the light of the stars and other
celestial bodies, namely to discover whether the same chemical elements as those of our earth are present
throughout the universe, was most satisfactorily settled in the affirmative; a common chemistry, it was shown,
exists throughout the universe.
- Sir William Huggins
Spectral Class of Stars
Definition: A form of classification used for stars based on their spectra. The Harvard classification, introduced in 1890 and modified in the 1920s, is based on the seven star types known as O, B, A, F, G, K, M:
O - hottest blue stars; ionised helium lines dominant
B - hot blue stars; neutral helium lines dominant, no ionised helium
A - blue blue-white stars; hydrogen lines dominant
F - white stars; metallic lines strengthen, hydrogen lines weaken
G - yellow stars; ionised calcium lines dominant
K - orange-red stars; neutral metallic lines dominant, some molecular bands
M - coolest red stars; molecular bands dominant
