Abstract
THE DRAPER CATALOGUE OF STELLAR SPECTRA.—Vol. xxvii. of the Annals of the Astronomical Observatory of Harvard College contains a catalogue of the spectra of 10,351 stars, nearly all of them north of the parallel of declination –25°, photographed with the 8-inch Bache telescope. As the work forms a part of the Henry Draper Memorial, it is suggested that it be designated as the Draper Catalogue. In order to produce the spectra, a prism 8 inches square and having a refracting angle of 13°, was fastened in front of the object-glass, with its refracting angle placed perpendicular to the earth's axis. The spectra obtained have been conveniently arranged in classes indicated by the letters A to Q. Of these, A, B, C, and D indicate varieties of Secchi's first type, E to L varieties of the second type, M the third type, and N the fourth type. The letter O is used for stars whose spectra consist mainly of bright lines, and the letter P is reserved for planetary nebulæ. The classes O and P closely resemble each other, and are regarded by Prof. Pickering as a fifth type of spectrum. All spectra not included in these classes are indicated by the letter Q. Viewed as the result of a preliminary survey of the types of the photographic spectra of stars, the catalogue is of the highest importance. But it is to the discussion of individual lines, which is to follow in another volume, that we have to look for detailed information which may improve our knowledge of stellar constitution.
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Our Astronomical Column. Nature 44, 89–90 (1891). https://doi.org/10.1038/044089a0
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DOI: https://doi.org/10.1038/044089a0