Popular Astronomy, Volume 22; Volume 1914Goodsell Observatory of Carleton College, 1914 |
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Common terms and phrases
Androm appear Aquarii Aquilae Astronomical August Aurigae Ba 9 bright Camelop canals Cancri Cassiop Cephei Ceti color comet constellation Cygni 20 dark Day Est.Obs Decl Delphini diameter disk distance Draconis earth eclipse ephemeris faint fainter Gemin giant stars Greenwich mean Harvard College Observatory Herculis Hydrae July Lacertae latitude Leonis Librae Lick Observatory light lines longitude Lyrae magnitude Mars Martian mass measures meridian miles Mo.Day Est.Obs Monoc month moon nebula night Ophiuchi orbit Orionis parallax Pegasi period Persei photographic planet plates polar cap POPULAR ASTRONOMY position Professor proper motion region right ascension Sagittarii satellite Scuti seen solar spectra spectrum SS Cygni stars of Class stellar Sun's Tauri telescope tion tude U. S. Naval Observatory VARIABLE STAR VARIABLE STAR OBSERVATIONS Virginis visible Vulpec Yerkes Observatory
Popular passages
Page 58 - Satisfactory evidence of thoroughly good health. The fellowship at all times must be used for purposes of serious study, and the fellow should be as free as possible from other responsibilities. Application...
Page 28 - Ball (RS, AM) — EXPERIMENTAL MECHANICS. A Course of Lectures delivered at the Royal College of Science for Ireland. By...
Page 468 - This phenomenon is not to be regarded as a pure illusion on the one hand, or an exact representation of objects on the other. It grows out of thft spontaneous action of the eye in shaping slight and irregular combinations of light and shade, too minute to be separately made out, into regular forms.
Page 196 - Barrister-at-law. A popular outline of leading facts, which may be easily grasped by any fairly educated person who is disposed to give a limited amount of time and thought to the matter and who happens to possess a small telescope and a good onera ula«3 Pp.
Page 341 - The differences in brightness between the stars of different spectral classes, and between the giant and dwarf stars of the same class, do not arise (directly at least) from differences in mass. Indeed, the mean masses of the various groups of stars are extraordinarily similar. (2) The surface brightness of the stars diminishes rapidly with increasing redness, changing by about three times the difference in colour-index, or rather more than one magnitude, from each class to the nest.
Page 341 - The mean densities of the giant stars diminish rapidly with increasing redness, from one-tenth that of the sun for class A to less than one-twentythousandth that of the sun for class M." In speculating on the nature of stellar radiation and stellar temperatures it is interesting to find that the observed radiometric data (see table 2) seem conclusive in showing that the early type (class M) stars are losing heat 3 to 4 times as fast...
Page 286 - Sun ; and all the very faint stars, — for example, those less than ^0 as bright as the Sun, — are red, and of Classes K and M. We may make this statement more specific by saying, as Hertzsprung does, * that there is a certain limit of brightness for each spectral class, below which stars of this class are very rare, if they occur at all. Our diagram shows that this limit varies by rather more than two magnitudes from class to class. The single apparent exception is the faint double companion...
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Page 284 - Hertzsprung — and many of the facts which will be brought before you are not new ; but the observational material here presented is, I believe, much more extensive than has hitherto been assembled. We can only determine the real brightness of a star when we know its distance ; but the recent accumulation of direct measures of parallax, and the discovery of several moving clusters of stars whose distances can be determined, put at our disposal far more extensive data than were available a few years...