Putting a New Spin on Galaxies: Horace W. Babcock,the Andromeda Nebula,and the Dark Matter Revolution

Babcock Horace W. , “The rotation of the Andromeda Nebula”, Lick Observatory bulletin, cdxcviii (1939), 41–51; and a brief announcement of his results that did not emphasize the unusualness of the measured rotation curve, “Spectrographic observations of the rotation of the Andromeda Nebula”, Proceedings of the Astronomical Society of the Pacific, 1 (1938), 174–5.

Babcock Horace W. , “On the rotation of the Andromeda Nebula”, Ph.D. diss., University of California, Berkeley, 1938.

Newton Isaac , The Principia: Mathematical principles of natural philosophy, transl. by Bernard Cohen I. and Whitman Anne (Berkeley, CA, 1999).

The following three equations are combined to find the equation for the mass: where Φ is the gravitational potential, and KE is the kinetic energy, Φ = -αGm²/r, 2KE + Φ = 0 and KE = 0.5m<v²〈. This yields m = r<v²〈/αG, where α is a factor depending on the mass distribution of the system, but which is usually of order unity. For detail see: Tayler Roger J. , The hidden universe (Chirchester, U.K., 1991), 194.

These three early papers are: Babcock Horace W. , “The Paschen series of hydrogen lines in the spectrum of the solar chromosphere”, Publications of the Astronomical Society of the Pacific, xliv (1932), 323–4; Harold D. Babcock and Horace W. Babcock, “Some new features of the solar spectrum”, Publications of the Astronomical Society of the Pacific, xlvi (1934), 132–3; and Horace W. Babcock, “Recent observations of solar chromospheric and disk spectra in the infrared”, Publications of the Astronomical Society of the Pacific, xlvii (1935), 321.

Osterbrock Donald , presentation at the Horace Welcome Babcock Memorial Symposium, Pasadena, CA, 21 May 2004, titled “Horace Babcock: born an astronomer”. Talks from the symposium were originally posted to www.ociw.edu/ociw/babcock (accessed 15 February 2005). That website is now defunct but a copy has been archived here: https://web.archive.org/web/20041217033944/ http://www.ociw.edu/ociw/babcock/. Osterbrock's presentation is archived here: https://web.archive.org/web/20041217234603/http://www.ociw.edu/ociw/babcock/osterbrocktalk.pdf (accessed 23 January 2014).

Abell George O. , “Award of the Bruce Gold Medal to Dr Horace W. Babcock”, Publications of the Astronomical Society of the Pacific, lxxxi (1969), 179–84, p. 180.

Pease F. G. , “The rotation and radial velocity of the central part of the Andromeda Nebula”, Proceedings of the National Academy of Sciences, iv (1918), 21–4. Vesto M. Slipher, “The detection of nebular rotation”, Lowell Observatory bulletin, ii (1914), 66.

Babcock , op. cit. (ref. 1), 50–1.

Babcock , op. cit. (ref. 1), 50.

Rubin Vera C. and Kent Ford W. , “Rotation of the Andromeda Nebula from a spectroscopic survey of emission regions”, Astrophysical journal, clix (1970), 379–403.

Zwicky Fritz , “Die Rotverschiebung von extragalaktischen Nebeln”, transl. by Brauer Friedemann in Helvetica physica acta, vi (1933), 110–27.

Babcock , op. cit. (ref. 1), 50.

Some of the other observations of note include the following: Holmberg Erik , “A study of double and multiple galaxies together with inquiries into some general metagalactic problems”, Annals of the Observatory of Lund, vi (1937), 162–173; M. Schwartzschild, “Mass distribution and mass-luminosity ratio in galaxies”, Astrophysical journal, lix (1954), 273–84; F. Kahn and L. Woltjer, “Intergalactic matter and the Galaxy”, Astrophysical journal, cxxx (1956), 705–17; Thornton Page, “Radial velocities and masses of double galaxies”, Astrophysical journal, cxvi (1952), 63–80; “M/L for double galaxies, a correction”, Astrophysical journal, cxxxvi (1962), 685–6.

Virginia Trimble's work on the history of dark matter has appeared in various astronomical venues since the 1980s. See, for example: “History of dark matter in galaxies”, in Oswalt Terry D. and Gilmore Gerard (eds), Planets, stars and stellar systems, v: Galactic structure and stellar populations (Dordrecht, 2013), 1091–118; “Dark matter”, in Noriss S. Hetherington (ed.), Encyclopedia of cosmology: Historical, philosophical and scientific foundations of modern cosmology (New York, 1993), 148–58; “History of dark matter in the universe (1922–1974)”, in B. Bertotti, R. Balbinot and S. Bergia (eds), Modern cosmology in retrospect (Cambridge, 1990), 355–62; “Dark matter in the universe: “Where, what, why?”, Contemporary physics, xxix (1988), 373–92; and “Existence and nature of dark matter in the universe”, Annual review of astronomy and astrophysics, xxv (1987), 425–72. Some works of Sidney van den Bergh cover similar ground, for example: “A short history of the missing mass and dark energy paradigms”, in Vicent Martínez, Virginia Trimble and María Jesús Pons-Bordería (eds), Historical development of modern cosmology, Astronomical Society of the Pacific conference series, cclii (2001), 75–84; and “The early history of dark matter”, Publications of the Astronomical Society of the Pacific, cxi (1999), 657–60.

Trimble in Hetherington, op. cit. (ref. 15), 149.

Trimble in Oswalt, op. cit. (ref. 15), 1100.

Smith Sinclair , “The mass of the Virgo Cluster”, Astrophysical journal, lxxxiii (1936), 23–30.

Zwicky Fritz , “On the masses of nebulae and of nebular clusters”, Astrophysical journal, lxxxvi (1937), 217–46. Fritz Zwicky, “Die Rotverschiebung von extragalaktischen Nebeln”, transl. by Friedemann Brauer in Helvetica physica acta, vi (1933), 110–27.

Helmut A . Abt (ed.), American Astronomical Society centennial issue of the Astrophysical Journal (Chicago, 2000), 267–96.

Oort Jan , “Stellar dynamics”, in Blaauw Adriaan and Schmidt Maarten (eds), Galactic structure (Chicago, 1965), 455–511. Jan Oort, “The force exerted by the stellar system in the direction perpendicular to the galactic plane and some related problems”, Bulletin of the Astronomical Institute of The Netherlands, vi (1932), 249–87.

Smith Robert W. , “Beyond the Galaxy: The development of extragalactic astronomy 1885–1965, part 2”, Journal for the history of astronomy, xl (2009), 71–107, p. 73. In the passage quoted Smith is making a general point; he is not referring to Babcock or early dark matter studies.

In the summer of 2002, I spent several weeks in the library at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Part of the work I carried out there was a close examination of all the titles and abstracts published from 1930 to 1950 in the main astronomy journals, in key observatory reports, and in the astronomy sections of Science abstracts. The pattern that emerged was very clear: astronomy papers in that period almost never explicitly included critiques or contradictions of prior work. There are, of course, exceptions to this pattern. Compared to other academic fields (for example, philosophy), however, the relative lack of inter-professional critique is remarkable.

van Helden Albert , “Building large telescopes, 1900–1950” and John Lankford, “The impact of photography on astronomy”, both in Owen Gingerich (ed.), Astrophysics and twentieth-century astronomy to 1950: Part A (Cambridge, 1984).

Abell , op. cit. (ref. 7).

Osterbrock , op. cit. (ref. 6), does not mention his source for this information, though the situation is described very similarly in Allan Sandage, “Horace Welcome Babcock”, Proceedings of the American Philosophical Society, cl (2006), 151–60, http://www.amphilsoc.org/sites/default/files/proceedings/150108.pdf, accessed 20 December 2013. The Babcock papers at the Huntington Library in California are from his time as observatory director and (at least according to the finding aid) they do not contain any materials relevant to the reception of Babcock's work on M31. Note that the McDonald Observatory conference title Osterbrock gives in the quotation, Dynamics and Structure of Galaxies, is probably a slip. Oort, who spoke at the event, refers to it as “the symposium on galactic and extragalactic structure”: Jan Oort, “Some problems concerning the structure and dynamics of the galactic system and the elliptical nebulae NGC 3115 and 4494”, Astrophysical journal, xci (1940), 273–306, p. 273 n. 1. Note, too, that while Trimble's writings seem to run together a meeting of the American Astronomical Society and the McDonald dedication conference, Helen Sawyer Hogg's (delightful) first-person account of the McDonald dedication and surrounding events refers to a nearby meeting of the southwestern division of the American Association for the Advancement of Science (AAAS rather than AAS) followed by a ‘symposium on galactic and inter-galactic structure’ associated with the observatory dedication itself: Helen Sawyer Hogg, “The dedication of the McDonald Observatory”, Journal of the Royal Astronomical Society of Canada, xxxiii (1939), 201–9, p. 204 and p. 207. The University of Texas library system holds an item entitled, “Program of the dedication of the McDonald Observatory and astronomical symposium on galactic and extragalactic structure, Fort Davis, Texas, May 5–8, 1939”.

Sandage , op. cit. (ref. 26), 154.

Oort , op. cit. (ref. 26), 305.

Interview of Horace W. Babcock by Spencer Weart on 25 July 1977, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD, USA, http://www.aip.org/history/ohilist/1038.html, accessed 20 December 2013. I am grateful to the Niels Bohr Library of the American Institute of Physics for permission to quote from this oral history interview.

See ref. 5.

Babcock Horace W. , “Radiations of the night sky photographed with a grating”, Publications of the Astronomical Society of the Pacific, li (1939), 47–50.

For details of Babcock's illustrious later career see: Abell, op. cit. (ref. 7); Weart's interview with Babcock, op. cit. (ref. 29); Arthur Harris Vaughan, “Obituary: Horace Welcome Babcock, 1912–2003”, Bulletin of the American Astronomical Society, xxxv (2003), 1454–5; George W. Preston, “Horace Welcome Babcock (1912–2003)”, Publications of the Astronomical Society of the Pacific, cxvi (2004), 290–4; Sandage, op. cit. (ref. 26); and George W. Preston, “Horace Welcome Babcock (1912–2003): A biographical memoir” (Washington, DC, 2007), http://books.nap.edu/html/biomems/hbabcock.pdf, accessed 23 December 2013.

Babcock , op. cit. (ref. 1), 51.

See, for example: Smith , op. cit. (ref. 22), 71, and Robert W. Smith, “Beyond the Galaxy: The development of extragalactic astronomy 1885–1965, part 1”, Journal for the history of astronomy, xxxix (2008), 91–119, p. 91.

Hoskin M. A. , “The ‘Great Debate’: What really happened”, Journal for the history of astronomy, xii (1976), 169–82.

Hubble finally established that each of the fifteen spirals sufficiently well studied up to that point all display a spectrographic rotation such that the spiral arms trail behind the central regions. Hubble included Babcock's spectrograph of the rotation of M31 among the fifteen spirals discussed. Hubble Edwin P. , “The direction of rotation in spiral nebulae”, Astrophysical journal, xcvii (1943), 112–18.

Trimble in Oswalt and Gilmore (eds), op. cit. (ref. 15), p. 1101. Trimble here means to cite N. U. Mayall and L. H. Aller, “The rotation of the spiral nebula Messier 33”, Publications of the Astronomical Society of the Pacific, lii (1940), 278.

Hubble Edwin P. , “N.G.C. 6822, a remote stellar system”, Astrophysical journal, lxii (1925), 409–33. Edwin P. Hubble, “A relation between distance and radial velocity among extra-galactic nebulae”, Proceedings of the National Academy of Sciences, xv (1929), 168–73.

Hubble Edwin P. , “Angular rotations of spiral nebulae”, Astrophysical journal, lxxxi (1935), 334–5.

Smith , op. cit. (ref. 22), 74. As part of the ‘settlement’ imposed by Adams, van Maanen published a companion piece to Hubble's paper acknowledging that systematic errors “make it desirable to view the motions with reserve”: Adriaan van Maanen, “Internal motions in spiral nebulae”, Astrophysical journal, lxxxi (1935), 336–7, p. 337.

See, for example, Hetherington Noriss S. , Science and objectivity: Episodes in the history of astronomy (Ames, IO, 1988), 83–110.

Smith , op. cit. (ref. 22), 73.

Hubble , op. cit. (ref. 39). A referee for this journal points out another possibility, namely that that Hubble did not change his mind, and was not really cold towards Babcock's results, and that Babcock was misremembering events. The referee further suggests that since Mayall was something of an acolyte of Hubble, it is plausible to think that Hubble would have known about Babcock's rotation curve before the two visited. These are good points.

To be accurate, it was not completely ignored. Raymond Coutrez published a brief notice, in French, of Babcock's Lick Observatory bulletin paper: “Note sur: La rotation de la nébuleuse d'Andromède, par Babcock H. W. , Ciel et terre, lvii (1941), 91–3.

Smith , op. cit. (ref. 34), 92.

Trimble in Oswalt, op. cit. (ref. 15), 1102.

Trimble in Bertotti, op. cit. (ref. 15).

The two important articles from 1974 are: Ostriker J. P. , Peebles P. J. E. and Yahil A. , “The size and mass of galaxies, and the mass of the universe”, Astrophysical journal, cxciii (1974), L1–l4; and Jan Einasto, Ants Kaasik and Enn Saar, “Dynamic evidence on massive coronas of galaxies”, Nature, ccl (1974), 309–10. One indication of the explosion of interest in dark matter at that time is that Trimble's 1987 review article, “Existence and nature of dark matter in the universe” (ref. 15), lists close to 800 citations relating to dark matter, almost all of which are from the decade preceding the date of her paper.

Ostriker J. P. and Peebles P. J. E. , “A numerical study of the stability of flattened galaxies: or, Can cold galaxies survive?”, Astrophysical journal, clxxxvi (1973), 467–80.

One indication of the robust on-going study of dark matter is that a Web of Science search for ‘dark matter’ returned 2,441 articles from the year 2012; 1,061 in 2002; 399 in 1992.

Vanderburgh William L. , “The dark matter double bind: Astrophysical aspects of the evidential warrant for General Relativity”, Philosophy of science, lxx (2003), 812–32. William L. Vanderburgh, “The methodological value of coincidences: Further remarks on dark matter and the astrophysical warrant for General Relativity”, Philosophy of science, lxxii (2005), 1324–35.

Sandage , op. cit. (ref. 26).