Nature January 8th 1874
On the spectra of Comets
Here is a summary of comet spectra by H Vogel published in
Poggendorffs Annalen
I will now give a summary of all the observations known to me of cometary spectra.
1. The
first comet examined by spectrum analysis is the Comet I. 1864. Donati found
its spectrum to consist of three bright bands, which (if one may judge from the
figure in Astr Nachr No. 1488) do not coincide with those of the hydrocarbon
spectrum.
2. Huggins
and Secchi observed Temple’s Comet I. 1866, and got from it a weak continuous
spectrum, in which Secchi saw three bright lines, Huggins only one. The line
seen by both was the brightest, and situated in the middle between b and
F of the solar spectrum; accordingly no coincidence with the hydrocarbon
spectrum.
3. In
the spectrum of Comet II. 867, the continuous spectrum was relatively so strong
that Huggins found it difficult to detect bright lines. “Once of twice”, he
says “I suspected the presence of two or three bright lines, but of this
observation I was not certain. The prismatic observation of this faint object,
though imperfect, appears to show that this small comet is probably similar in
physical structure to comet I.1866” In this case again probably no hydrocarbon.
4. Brorsen’s
Comet I. 1868 was observed by Huggins and Secchi. Both observed three zones of
light; The middle one being the brightest, and lying in the green; while its
brightest part was somewhat less refrangible than the brightest line of the air
spectrum. From this observation, and the determination of the position of the
other two faint bands, it appears that the comet spectrum was neither similar
to that of nitrogen, nor to the hydrocarbon spectrum.
5. Winnecke’s
Comet II.1868, was also observed by Huggins and Secchi. The measurements and
direct comparisons of Huggins gave an agreement of the cometary spectrum with
that of carbon in olefiant gas. From Secchi’s measurements it appears that the
sharply defined side of the middle band (towards the red end), nearly coincided
with the line group b of the solar spectrum; at which part also the
beginning of the middle band of the spectrum of hydrocarbon id situated.
6. Comet
I. 1870 was observed by Wolf and Rayet; the spectrum consisted of three bright
bands, whose position, however, was not accurately determined.
7. Comet
I. 1870 was observed by Huggins and myself. Huggins found three bands, I only
two. The measurements of the bands observed in common agree well; the spectrum
appears to be identical with that of Brosen’s Comet.
8. Comet
III. 1871 (Encke) was observed by Huggins three days, by Young four and by
myself six; it showed, as usual a spectrum of three bands. Huggins thought this
agreed with the hydrocarbon spectrum ; while young and I observed no such
coincidence.
9. Comet
IV. 1871 (Tuttle), examined only by me, gave a spectrum of three bands.
Accurate measurements of their positions showed no coincidence with the
hydrocarbon spectrum.
w
