Identifier: elementsoftheore00whit_0 (find matches)Title: Elements of theoretical and descriptive astronomy, for the use of colleges and academiesYear: 1901 (1900s)Authors: White, Charles JSubjects: Astronomy.Publisher: New York: J. Wiley & sonsContributing Library: University of Florida, George A. Smathers LibrariesDigitizing Sponsor: University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan FoundationView Book Page: Book ViewerAbout This Book: Catalog EntryView All Images: All Images From BookClick here to view book online to see this illustration in context in a browseable online version of this book.Text Appearing Before Image:la, Rigel,Procyon, and Spica are blue; Sirius, Vega, and Altair are green;and Arcturus is yellow. The components of the double stars are often of different co-lors; blue and yellow, or green and yellow; and, less frequently,white and purple, or white and red. The following table con-tains a few of the many instances of such stars which might begiven:— Name. Magnitudeof Components. Color of the Larger. Color of the Smaller. 4 7 5 6 5 8 3 7 5 6 3 7 Yellow.Pale Green.Orange.Pale Orange.White.Yellow. Purple. Blue. Blue. Sea Green. Purple. Blue. When the colors of the components are complementary, and thecomponents are of very unequal size, it is possible that only oneof the colors may really exist; the other being, according to alaw of Optics, merely the result of contrast. Such an opinion isheld bysome astronomers; but the objection is raised to it byothers that, if one of these colors is only accidental, it ought tcdisappear when the eye is shielded from the light of the sta? PLATE 71Text Appearing After Image:NEBULA. 1. ANNULAR NEBULA, 57 M LYR>£. 2. PLANETARY NEBULA, 3614 H VIRGINIS. 3. NEBULOUS STAR, i ORIONIS. 4. SPIRAL NEBULA, 99 M VIRGINIS.%. CRAB NEBULA IN TAURUS. KEBUUE. 229 which has the other color: which, however, u very far frombeing the case. Another objection is that a similar phenomenonought to be seen in all colored stars whose components are ofunequal sizes: whereas many double stars are found in whichboth components have the same color, sometimes red and some-times blue. In one of Struves catalogues, out of 596 doublestars, there were:— 295 pairs, both white:118 pairs, both yellowish or reddish:63 pairs, both bluish:120 pairs of totally different colors.In a few instances stars have changed their color. Sirius,for instance, is now green; but both Ptolemy and Seneca ex-pressly state that in their day it had a reddish hue. Capella,which is now blue, was formerly red. Some observers state thatseventeen stars of the first magnitude are colored, and that sevenof these havNote About ImagesPlease note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
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