Lick Observatory Bulletins Volume 6

Lick Observatory Bulletins Volume 6

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...of the time of observation. These circumstances necessitated the use of a wider slit than would otherwise have been employed in order to insure a sufficient amount of light entering the spectrograph. As a result the plates do not compare very favorably in the matter of definition with those of Nova Persei, taken partly with the same apparatus. Notwithstanding this imperfection, however, the plates are capable of furnishing reliable data. Before giving the results of such plates as have been measured it may be well to call attention to the difficulty of describing observations of spectra of this character. Putting the matter briefly, the spectrum of a new star may be said to present phenomena of nearly every known spectral character, with the possible exception of absolutely monochromatic or brightline radiation. There are in turn broad emission bands and narrow ones, some of the former partaking of the character of diffuse maxima, and others of radiations more or less uniform in intensity between definite limits of wave-length, beyond which they hardly extend at all, while a few narrow ones present the appearance, under low dispersion, of hazy bright lines. In some cases the bands are homogeneous throughout; in others they are marked by a complexity of structure that is in fact bewildering.2 More or less the same variety exists in the dark bands, some of which are broad while others are comparable in width with the Fraunhofer lines in the solar spectrum. These remarks are general and are based on observations of the spectra of several novae. They describe facts, in the main, quite familiar to observers of these objects, but which may not always be fully appreciated by others. Many bands, for instance those due to hydrogen, are undoubtedly more

Product details

  • Paperback | 68 pages
  • 189 x 246 x 4mm | 141g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123664204X
  • 9781236642042