The Observatory, Band 4

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Editors of the Observatory, 1881
 

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Seite 225 - IV. Stars whose light is continually varying, but the changes are repeated with great regularity in a period not exceeding a few days. Examples, ft Lyrce and 8 Cephei.
Seite 335 - DM. 81°25. annular eclipse. In this case, if the motion was uniform, the duration of the minimum light would equal only one ninth of that of increase or decrease. The effect of the curvature, or ellipticity, of the path would not greatly affect this conclusion. A very...
Seite 228 - Lyree, ijAquilce, and 8 Cephei, have been observed with great care, so that their variations are known with much precision. Each will therefore be discussed in turn, according to the following method. As the variation is periodic, it will be convenient to denote the time by an angle, v, such that 360° shall correspond to one period or revolution of the star. We now wish the light * Poggendorff's Annalen, xxxiii.
Seite 225 - I. Temporary stars. Examples, Tycho Brahe's star of 1572, new star in Corona, 1866. II. Stars undergoing great variations in light in periods of several months or years. Examples, o Cell and ^ Cygni.
Seite 233 - Trans., 1880, p. 669) to the head of the comet, so that the nucleus should be upon one half of the slit. After one hour's exposure the open half of the slit was closed, the shutter withdrawn from the other half, and the instrument then directed to Arcturus for fifteen minutes.
Seite 118 - ... elliptical there might be only one minimum. In the case of Algol more than half the light is cut off at the minimum; consequently one body must be darker than the other. As no second minimum has ever been observed, it is probable that the eclipsing body is not self-luminous. We must now show that neither of the other theories named above will explain the variations of Algol and of other stars of the fifth class. The regularity of the variation disposes of the theory of a volcanic eruption, a...
Seite 293 - ... observations will have little value, unless they are reduced and the light curve found. A vast number of excellent observations of these stars already exist, including the larger part of those of Argelander, which will have no value until they are reduced. 2. Determination of the light curve of the stars of the fourth class photometrically. This may be done with great accuracy by an instrument similar to that described in the Annals of the Harvard College Observatory, xi. 4, Figs. 1 and 2. The...
Seite 270 - No natural explanation can be offered for such terms, and the reduction might be thought accidental did it not occur in so many different curves. A careful distinction must be made between these terms and those which might be assumed empirically, since their form is clearly pointed out by the residuals. If we tried to represent the residuals by a function of 4...
Seite 233 - ... (in some form, possibly in combination with hydrogen), which I observed in the spectra of the telescopic comets of 1866 and 1868. In the continuous spectrum shown in the photograph, the dark lines of Fraunhofer can be seen. This photographic evidence supports the results of my previous observations in the visible spectra of some telescopic comets. Part of the light from comets is reflected solar light, and another part is light of their own. The spectrum of this light shows the presence in the...
Seite 227 - L = a -(- b sin v -\- c cos v -\- d sin 2 v -(- e cos 2 v ; a here denotes the mean light, v the angle of rotation, b and c are constants depending on the comparative brilliancy of the two hemispheres, each of which is supposed to be of uniform intensity, but one brighter than the other ; d and e depend on a supposed deviation of the body from the form of a solid of revolution. This equation may also be written in the form L = a...

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