An Astronomical Symbiosis: Stellar Evolution and Spectral Classification (1860 - 1910)

The interdependence of schemes of spectral classification and theories of stellar evolution is examined and discussed in the context of the work of major 19th and early 20th century astronomers, including A. Secchi, H. Vogel, W. Huggins, N. Lockyer, A. Ritter, F. McClean, W.H.S. Monck, A. Maury, W.P. Fleming, E.C. Pickering, E. Hertzsprung, and H.N. Russell. The nineteenth century concept of evolution through gravitational contraction is identified as a dominant theme, and is analysed within the historical context of the establishment and exploitation of the energy conservation laws during the mid-nineteenth and early twentieth centuries. The factors affecting studies of stellar evolution in the late nineteenth and early twentieth centuries, including developing techniques in astronomical spectroscopy, stellar kinematics, laboratory spectroscopy, astrometry, photography, and the application of physical theory to astronomical problems, form a necessary background to this theme. Finally, the early development of the Hertzsprung-Russell Diagram is critically examined.