Stellar Motions: With Special Reference to Motions Determined by Means of the SpectrographYale University Press, 1913 - 328 pages |
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Common terms and phrases
1-prism Algol angle antapex apex apparent approximately Astr binary systems bodies bright lines bright star brighter Centauri centre of mass Class B stars Classes G column components computed corresponding curve density determined direction dispersion displacement double stars Earth eccentricities eclipse effect equation error fainter Herschel hydrogen lines investigation Kapteyn Lick Obs light line of sight maximum mean measured methods micrometer Milky Mills spectrograph Mount Hamilton nebulæ number of stars Observatory observed velocities orbit Orion parallactic parallax Pegasi photographic plane position prisms proper motions proper-motion radial velocities reference relative right ascension rotation Secchi's TYPE sin³ Sirius slit solar motion solar system solution spectral classes spectral types spectrograph spectroscopic binary spectrum speed sphere ẞ Lyræ star's stellar distances stellar motions stellar system Sun's TABLE Tauri telescope tion TYPE II stars Ursa V₁ variable stars violet visual magnitude wave lengths
Popular passages
Page 159 - ... that the small excess of 45 found within this strip is due to the fact that more stars were observed and investigated, and, therefore, more proper motions found. Besides this, some uncertainty may exist as to the reality of the minuter proper motions. The conclusion is interesting and important. If we should blot out from the sky all the stars having no proper motion large enough to be detected, we should find remaining stars of all magnitudes ; but they would be scattered almost uniformly over...
Page 10 - If a beam of daylight be admitted into a dark room by a crevice -fa of an inch broad, and received by the eye at the distance of 10 to 12 feet through a prism of flint glass, free from veins, held near the eye, the beam is seen to be separated into the four following colours only, red, yellowish green, blue, and violet, in the proportions represented in fig.
Page 9 - Measures of stellar distances present difficulties so great that even today we possess reliable knowledge of the approximate distances of not over one hundred stars. At no point in astronomical science is fuller knowledge more desirable, more pressingly urgent, than in the subject of stellar distances ; or speaking technically, of stellar parallaxes.
Page 248 - The radiation received from a plane surface varies as the cosine of the angle between the line of sight and the normal to the surface.
Page 10 - I cannot conclude these observations on dispersion without remarking that the colours into which a beam of white light is separable by refraction, appear to me to be neither 7, as they usually are seen in the rainbow, nor reducible by any means (that I can find) to...
Page 218 - The rigidly scientific cast of Professor Campbell's mind prevents him from attempting to give a decisive and final answer to this question.
Page 10 - E, the two limits of violet. But C, the limit of green and blue, is not so clearly marked as the rest, and there are also on each side of this limit other distinct dark lines — f and g — either of which, in an imperfect experiment, might be mistaken for the boundary of these colours.
Page 10 - Fraunhofcr's line*. of the spectrum is somewhat confused, which seemed in part owing to want of power in the eye to converge red light. The line B, between red and green, in a certain position of the prism, is perfectly distinct ; so also are D and E, the two limits of violet ; but c, the limit of green and blue, is not so clearly marked as the rest : and there are also, on each side of this limit, other distinct dark lines, f and g, either of which in an imperfect experiment might be mistaken for...