Julius Scheiner – 19th century extragalactic spectroscopy

Juluis Scheiner published a lot in German language and made a lot of solar and stellar research. I’m concentrating on his English production on extragalactic issues.

Scheiner (1898) studied the reason why nebular spectra sometimes showed Hβ lines while showing little or no Hα lines, which seemed to go against the common knowledge back then that Hα lines are brighter than Hβ lines. He had trouble of studying the phenomenon with spectrophotometers because they weren’t able to measure so faint light as needed in the study. He then made a remarkable experimental setup:

The Geissler tube was set up at the distance of distinct vision (or at a distance somewhat greater), and viewed with a direct-vision system of prisms, the capillary bore of the tube serving as a slit. Between the tube and the prism-system two Nicol prisms were introduced, one of which could be turned and its angular displacement measured. By turning this prism the hydrogen lines could be made to vanish.

With this setup, he found an interesting thing:

Then on weakening the light, there occurred, at a certain intensity, an apparent equality of the two lines, after which Hα disappeared and then Hβ.

Scheiner & Wilsing (1902) also studied some issues relating to different spectral lines and their intensities in nebulae.

Scheiner (1899) discussed the spectrum of the Andromeda nebula (Messier 31) and showed that it consisted of stars. He then proceeded to discuss the Milky Way in the light of that evidence:

The irregularities of the Milky Way, especially its streams, can be quite well accounted for, as Easton attempted to do, if they are regarded as a system of spirals and not as a ring system.

And further:

In spite of the unfavorable projection under which we see the Milky Way, it does not seem impossible to establish the spiral character of the principal forms, and, furthermore, to bring the proper motions of the stars of the Milky Way into relation with this.

Apparently, this spectrum of Scheiner of M31 was the first succesful spectrum of a galaxy (Rubin, 1995). There seemed to be some minor dispute with Edward Fath and Scheiner over the spectrum of M31 as discussed in Scheiner (1909).

Julius Scheiner links

MNRAS: Obituary
Wikipedia: Julius Scheiner

References

Rubin, 1995, ApJ, 451, 419, “A Century of Galaxy Spectroscopy”

Scheiner, 1898, ApJ, 7, 231, “On the Spectrum of Hydrogen in the nebulæ”

Scheiner, 1899, ApJ, 9, 149, “On the spectrum of the great nebula in Andromeda”

Scheiner, 1909, ApJ, 30, 69, “Note on the Spectrum of the Andromeda Nebula”

Scheiner & Wilsing, 1902, ApJ, 16, 234, “Determination of the intensity-ratios of the principal lines in the spectra of several gaseous nebulae”

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