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The discovery of the spiral arms of the Milky Way

Published online by Cambridge University Press:  04 August 2017

Owen Gingerich
Owen Gingerich*
Affiliation:
Harvard-Smithsonian Center for Astrophysics

Abstract

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Attempts in the 1930s and 1940s to determine the spiral structure of the Milky Way by star counting methods, essentially the continuation of the work of the Kapteyn Astronomical Laboratory, failed to reach this goal. A new foundation for the search was laid by Walter Baade in his studies of stellar populations. With the recognition that highly luminous objects, especially H II regions, would outline the spiral structure, W.W. Morgan and his young associates Sharpless and Osterbrock carried out the observational program that first delineated, in 1951, the nearby arms of the Milky Way. The full paper was never published, so the historical details have remained somewhat vague, primarily because the 21-cm discoveries so quickly overtook the optical researches.

Type
PART I: HISTORY OF GALACTIC RESEARCH
Information
Symposium - International Astronomical Union , Volume 106: The Milky Way Galaxy , 1985 , pp. 59 - 70
Copyright
Copyright © Reidel 1985 

References

Notes and References

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2. Baade, W., Astrophys. J. 100, pp. 137–150, 1944.Google Scholar
3. Baade, W. to Oort, J., 23 September 1946. I wish to thank Prof. Oort and the Niels Bohr Library, AIP, for permission to examine and use the microfilm of this correspondence.Google Scholar
4. Oort, J. to Baade, W., 11 January 1947.Google Scholar
5. Baade, W. to Goldberg, L., 18 May 1949. I wish to thank Prof. Goldberg for the use of this material.Google Scholar
6. Baade, W., Publ. Univ. Michigan Obs. 10, pp. 7–17, 1951.Google Scholar
7. Nassau, J.J. and Morgan, W.W., Publ. Univ. Michigan Obs. 10, pp. 43–50, 1951.Google Scholar
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9. Struve, O., Leaflet Astron. Soc. Pacific No. 285, January, 1953.Google Scholar
10. Oral history interview with W.W. Morgan, American Institute of Physics. I wish to thank Prof. Morgan and the Niels Bohr Library, AIP, for permission to quote from this interview. The quoted passage has been somewhat condensed.Google Scholar
11. Oral history interview with D.E. Osterbrock, on deposit at American Institute of Physics. I wish to thank Prof. Osterbrock for permission to quote from this interview and for his comments on the draft of this article. Photographs of the H II regions made with the Henyey-Greenstein camera are found in Sharpless, S. and Osterbrock, D., Astrophys. J. 115, pp. 89–93, 1952.Google Scholar
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13. Sky Telesc. 11, p. 138, 1952; reprinted in Lang, K. and Gingerich, O. (eds.), Source Book in Astronomy and Astrophysics, 1900–1975, pp. 638–642, (Cambridge, Mass., 1979); the abstract of the Morgan, Sharpless, Osterbrock paper appeared in Astron. J. 57, p. 3, 1952.Google Scholar
14. Morgan, W.W. to Gingerich, O., 25 March 1982.Google Scholar
15. See Lang, K. and Gingerich, O., op. cit. [note 13], pp. 643–651.Google Scholar
16. The Van Albada mentioned here is G.B. van Albada, later Director of the Lembang Observatory and of the Astronomical Institute at Amsterdam. (Editor.) Google Scholar