This page consists of a chronologically ordered bibliography of articles related to the astrometric measurements of internal motions of stellar systems. (In essense, Adriaan van Maanen resurrected.) The main area of concern has to do with, but is not limited to, spiral nebulae (currently called galaxies). Abstracts, highlights, and thumbnail sketches of a number of the articles, are being added.

The compiler of this bibliography is fully aware that, at the present, about 97 percent of the articles in print since 1935 (and especially those on the world wide web) dealing with van Maanen's sixteen plus Mt. Wilson papers on internal motions of spiral nebulae (published in the 1916-1930 timeframe), paint him as being mistaken in his findings. In contrast to the majority opinion against van Mannen, it can be seen that he was not a lone voice crying in the wilderness. There may even come a need to resume astrometric studies on the internal motions in spiral nebulae.

Journal Abbreviations

1915

Curtis, Heber D., "Proper Motions of the Nebulae," PASP, 27, 214-220 (1915) - NADS
    [This is a report on an early nebular proper motions study done using photographs made with the Crossley Reflector at Lick Observatory.] The average time between early and late plates was 13.85 years. [pp.214-215]
    The general results [for average yearly proper motions], by classes are as follows:--
1. Large, Diffuse Nebulosities: 0."036 - - - - - - - - - - - - - - - - - - - - - - - - - 10 objects.
2. Planetary and Annular Nebulae: 0."028 - - - - - - - - - - - - - - - - - - - - - - 17 objects.
3. Very Small Nebulae (many show evidence of spiral character ): 0."040  - - - - 47 objects.
4. Large Spiral Nebulae: 0."033 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 66 objects.
[p. 215]
    The accuracy of the measures varies considerably, ... and would be much higher were the old plates as uniformly sharp and good as the late plates. [p.215]
    A number of the better determined nebulae showing numerous condensations were examined graphically for possible evidence of rotation, but none were found..[p. 217]
    The average radial velocity of 73 planetary type nebulae . . . is thirty-nine kilometers per second. This value, combined with the average proper motion found, would make the average distance of this class of nebulae about one thousand light years, a value which is not improbable, as all these objects are Milky Way Phenomena. [p.217]
    The radial velocities of very few spirals have been determined as yet; the mean of SLIPHER'S results is 400 kilometers per second, a truly enormous value, which may be considerably changed when a larger number have been determined. On this basis and on the assumption that these objects are moving truly at random in space, the average distance of the spirals is of the order of ten thousand light years, a distance that many will regard as too small. [pp. 217-218]

van Maanen, Adriaan, "List of Stars with Proper Motion Exceeding 0".50 Annually," ApJ, 41, 187 (1915) - NADS

Porter, J.G., "Note on van Maanen's list of stars with motion exceeding half a second annually," AJ, 29, 46 (1915) - NADS
    These two articles are included because investigations into nebular motions hinged on the use of selecting slowly moving foreground stars as a reference system. [Added 22 March 2010.]

1916

Lampland, C. O., "Preliminary Measures of the Spiral Nebulae N.G.C. 5194 and N.G.C. 4254 for Proper Motion and Rotation," PA, 24, 667 (1916) - NADS
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Pease, Francis G., "The Spiral Nebula Messier 33," PASP, 28, 33-34 (1916) - NADS
    A spectroscopically determined radial velocity of -278 km/sec for a bright knot some ten minutes of arc from the nucleus of M33, as compared to the systemic [motion as a whole] radial velocity of -70 km/sec, implies some degree of internal motions for the nebula. "Unfavorable weather has prevented the obtaining of spectra of other knots to determine whether there is a progressive change in type from the nucleus to the edge and also whether or not the difference in velocity means a rotation." [See the (1971) Gordon entry below.]
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Van Maanen, A., Ritchey, G.W., Keeler, J.E., Perrine, C.D., Curtis, H.D., "Preliminary Evidence of Internal Motion in the Spiral Nebula Messier 101," ApJ, 44, 210 (1916) - NADS - [Plate VII is not scanned. NADS abstracts does not list van Maanen's co-authors.]
    See van Maanen's Plate VII that shows his measurements of Internal Motions in Messier 101. [This scanned in image, found with Google.com, was tucked away in the Astronomy section of Ron Doel's Science in the Twentieth Century webpages. Professor Doel kindly disagrees with this compiler's contention that van Maanen's internal motions of spiral nebulae were unfairly treated by his colleagues.]

1917

Barnard, E. E., "The Proper Motion of the Great Nebula of Andromeda," AJ, 30, 175-176 (1917) - NADS
    "Though the distances are discordant, they show that no considerable relative motion has occurred in the past eighty years."
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Jeans, J. H., "Internal Motion in Spiral Nebulae," Obs, 40, 60 (1917) - NADS
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Kostinsky, S., "Probable Motions in the Spiral Nebula Messier 51 (Cannes Venatici) Found With the Stereo-comparator. Preliminary Communication," MNRAS, 77, 233 (1917) - NADS
    Stereoscopic comparison of plates of Messier 51, taken in March 1896 and in April 1916, found "almost indisputable displacements of some characteristic knots lying on the spirals."... "Preliminary stereoscopic measures on the above-mentioned plates of 36 single knots showed me that their observed proper motions with regard to the centre of the nebula seem to have a systematic character in the different parts. They led me to the following preliminary conclusions: -

Shapley, Harlow, "Note on the Magnitudes of Novae in Spiral Nebulae," PASP, 29, 213-217, (1917) - NADS
    Their authenticity [eleven novae in spiral nebulae] can hardly be doubted,   . . .  On the basis of chance, Curtis has noted the impossibility of considering these novae [to be] physically unrelated to the spirals with which they are associated. [p. 214]
    Taking the averages as referring to similar luminosity, possibly an uncertain procedure . . . , we observe that the difference in apparent brightness calls for a distance at least 50 times as great for these larger spiral nebulae as for the average novae of the galactic system. [p. 215]
    If we are to believe that a spiral nebula, . . . , is a remote stellar system, its most luminous stars must be fainter than magnitude 21, since even in its thinner parts there is no hint of resolution into distinct stars on the best of plates; nor can the nebulous condensations, with magnitudes between 15 and 20, be considered an accumulation of stars brighter than magnitude 21. This point is important, for, if in the hypothetical galactic system the brightest stars are comparable with the bright stars of our own galaxy, the minimum distance of the Andromeda Nebula must be of the order of a million light years.

1919

Schouten, W.J.A., "Probable Motions in the Spiral Nebula Messier 51 (Cannes Venatici)," Obs, 42, 441-444 (1919) - NADS
    "The numerous measures performed by Mrs. Dorothea Roberts on photographs of Messier 51 (Rivista di Astronomia, 1910, pp. 31-41 & 62-85) have been published in a form making it impossible (alas!) to deduce the proper-motion of the nebulous points. Therefore we have not been able to compare our results with hers. Kostinsky (Monthly Notices, 1910, pp. 31-41 & 62-85)* has found annual motions of the order 0".04 - 0".05 for a number of points in Messier 51. This agrees with our results"....
    "The rotational movement (2) found for the nebula Messier 51 is considerably smaller than that determined by Dr. Van Maanen (Contr. Mount Wilson Observ. No. 118) for the spiral nebula
Messier 101"
    * [Year and page numbers are typographical repeats from Shouten's first reference in the previous sentence. The actual reference is: MNRAS, 77, 233 (1917).]
. ___

Van Maanen, A., Willis, H.C., Oosterhoff, P.T., Investigations on Proper Motion, Library of Congress Call Number QB4.M93 no. 167-168, (1919) - NADS [Abstract not available.]

1920

Curtis, Heber D., "Modern Theories of the Spiral Nebulae," JRASC, 14, 317-327 (1920) - NADS
    The most anomalous and inexplicable feature of the spiral nebulae is found in their peculiar distribution. They show an apparent abhorrence for our galaxy of stars, being found in greatest numbers around the poles of our galaxy. In my counts I found an approximate density of distribution as follows:

Galactic Latitude +45° to +90° - - - - - - - - - - - - - - - - - - - - - 34 per square degree.
Galactic Latitude –45° to –90° - - - - - - - - - - - - - - - - - - - - - 28 per square degree.
Galactic Latitude +30° to +45° and –30° to –45° - - - - - - - - - - 24 per square degree.
Galactic Latitude –30° to +30° - - - - - - - - - - - - - - - - - - - - - - 7 per square degree.