Stellar Evolution and the Spectral Classes of Stars

In broad outline stars are thought to evolve by the following sequence of events. First, there is self-gravitational accretion from the cooled primordial 

When 10% of the hydrogen in the core has been consumed gravitational contraction again occurs until at a temperature of 2 X 10 K helium burning (fusion) can occur. This is followed by a similar depletion, contraction and temperature rise until nuclear reactions involving 

Marschall, The Supernova Story, Plenum Press, New York, 1989, 276 pp. P. Murdin, End in Fire The Supernova in the Large Magellanic Cloud, Cambridge University Press, 1990, 253 pp. 

1890s First systematic studies on the terrestrial abundances of the elements 

1919 First artificial transmutation of an element Nfa.pl gO 192S-8 First abundance data on stars (spectroscopy) 

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