The Study of Stellar Evolution: An Account of Some Recent Methods of Astrophysical ResearchUniversity of Chicago Press, 1908 - 252 pages |
Other editions - View all
Common terms and phrases
60-inch mirror absorption advantages appear astronomical Astrophysical axis bright lines calcium calcium flocculi calcium vapor camera CHAPTER chromosphere clouds coelostat concave condensation constructed dark lines diameter disk dispersion Earth eclipse electric employed exposure eye-piece faculae feet focal length gases glass graph grating heat heavens heliostat hydrogen hypothesis inches instrument intensity investigations Kenwood laboratory lens Lick Observatory light luminous ment Messier 11 meteorites method motion Mount Wilson moving nebulae nebular hypothesis object-glass objects observations obtained optical orbits phenomena photographic plate photosphere plane position prism produced prominences radiation rays red stars reflecting telescope reflector refractor regions resolving power Ritchey rotation seen shown Snow telescope solar image Solar Observatory solar prominences solar spectrum spectrograph spectroheliograph spectroscope spot spectra stellar evolution stellar spectra sun-spots Sun's sunlight surface tele temperature tion tube velocity violet Yerkes Observatory Yerkes telescope
Popular passages
Page 109 - If the Theory of making Telescopes could at length be fully brought into practice, yet there would be certain Bounds beyond which Telescopes could not perform. For the Air through which we look upon the Stars, is in a perpetual Tremor; as may be seen by the tremulous Motion of Shadows cast from high Towers, and by the twinkling of the fix'd stars. The only remedy is a most serene and quiet Air, such as may perhaps be found on the tops of the highest Mountains above the grosser Clouds.
Page 52 - I was looking at a reflection of the illuminated slit from one of its faces. This thought was scarcely more than momentary; then the true interpretation flashed upon me. The light of the nebula was monochromatic, and so, unlike any other light I had as yet subjected to prismatic examination, could not be extended out to form a complete spectrum. After passing through the two prisms it remained concentrated into a single bright line, having a width corresponding to the width of the slit, and occupying...
Page 52 - I looked into the spectroscope. No spectrum such as I expected! A single bright line only! At first I suspected some displacement of the prism, and that I was looking at a reflection of the illuminated slit from one of its faces. This thought was scarcely more than momentary ; then the true interpretation flashed upon me. The light of the nebula was monochromatic, and so, unlike any other light I had as yet subjected to prismatic examination, could not be extended out to form a complete spectrum.
Page 32 - This tube, 64 feet in length, is supported at its middle point by the declination axis, which in its turn is carried by the polar axis, adjusted to accurate parallelism with the axis of the earth. By means of driving mechanism in the upper section of the iron column the whole instrument is turned about this polar axis at such a rate that it would complete one revolution in twenty-four hours. Although the moving parts weigh over 20 tons, the telescope can be directed to any part of the sky by hand,...
Page 122 - ... breeze blows for a large part of the day, but it attains only a low velocity, which decreases in passing from the valley to the mountain tops and in going inward from the coast. Mount Wilson is one of many mountains that form the southern boundary of the Sierra Madre range. Standing at a distance of thirty miles from the ocean, it rises abruptly from the valley floor, flanked only by a few spurs of lesser elevation, of which Mount Harvard is the highest. Except for a narrow saddle, Mount Wilson...
Page 34 - Kitchey of the observatory staff simply -places before the (isochromatic) plate a thin screen of yellow glass, which cuts out the blue rays, but allows the yellow and green rays to pass. As isochromatic plates are sensitive to yellow and green light there is no difficulty in securing an image with the rays which the object-glass unites into a perfect image.
Page 122 - ... west, beyond the saddle leading to Mount Harvard, the ridge of Mount Wilson forms the upper extremity of Eaton Canon, which leads directly to the San Gabriel Valley. East and north of Mount Wilson lies the deep canon through which flows the west fork of the San Gabriel River, and beyond this rises a constant succession of mountains, most of them higher than Mount Wilson, which extend in a broken mass to the Mojave Desert. The Sierra Madre range forms the northern boundary of the San Gabriel Valley,...
Page 175 - This anterior state was itself preceded by other states, in which the nebulous matter was more and more diffuse, the nucleus being less and less luminous. We arrive," Laplace says, " in this manner, at a nebulosity so diffuse, that its existence could scarcely be suspected.
Page 3 - We are now in a position to regard the study of evolution as that of a single great problem, beginning with the origin of the stars in the nebulae and culminating in those difficult and complex sciences that endeavor to account, not merely for the phenomena of life, but for the laws which control a society composed of human beings.
Page 175 - But in what manner has the solar atmosphere determined the motions of rotation and revolution of the planets and satellites? If these bodies had penetrated deeply into this atmosphere, its resistance would cause them to fall on the Sun. We may, therefore, suppose that the planets were formed at its successive limits, by the condensation of zones of vapours, which it must, while it was cooling, have abandoned in the plane of its equator.