The Astrophysical Journal, Volume 56University of Chicago Press, 1922 - Astrophysics "Letters to the Editor" issued as Part 2 and separately paged from v. 148, 1967. Beginning in 2009, the Letters published only online. |
Other editions - View all
Common terms and phrases
absolute magnitude absorption Aquilae Astronomical Astrophysical Journal Bon Aon 0.8 bright lines brighter central stars color color-index column comparison stars components computed continuous spectrum correction corresponding curve Cygni derived determined deviation diameter diffuse nebulae distance distribution electron emission nebulae emission spectra equation error etalon exposure faint fainter formula furnace galactic nebulae giant stars give given helium Hẞ hydrogen hydrogen lines indicate intensity interferometer investigation Kapteyn Lick Observatory light luminosity mean measured method Mount Wilson Observatory nebulosity objects observed obtained orbit Orion parallax photo-visual magnitude photographic magnitudes planetaries plates points probably proper motion radial velocities radiation ratio reflector region relative short etalon slit spectral type spectrograms spectroscopic spirals stars involved stellar Table Taurus telescope temperature tion triplets tube values vapor variable Venus wave-lengths Wilson Contr ΙΟ Ο.ΟΙΟ
Popular passages
Page 338 - The subtitles should together form a complete index of the new 'information; that is they should include every measurement, observation, method, suggestion, and theory which is presented as new and of value in itself. They should be complete in themselves and independent of the main title of the article. 3. Text. — Write a paragraph summarizing the main group of results and including the corresponding subtitle either all at the beginning or with parts scattered through the text; and then do likewise...
Page 183 - It seems more reasonable to place the active agency in the relatively dense and exceedingly hot stars than in the nebulosity, and this leads to the suggestion that nebulosity is made luminous by radiation of some sort from stars in certain physical states. The necessary conditions are confined to certain ranges in stellar spectral type and hence are possibly phenomena of effective temperature. The nebulous material itself must be in a physical state sensitive to the stellar radiation, and close enough...
Page 146 - However, I think my enthusiasm for the matter will be equal to (say) six or seven years of such work
Page 338 - The increase in size of an image in the case of a perfectly sharp image is due to multiple reflection, refraction, and diffraction of the image-forming light by the grains of silver halide, which, in thickly packed layers, constitute the emulsion. The light is thus deflected from its original direction perpendicular to the plate in a succession of steps until its direction of flow, measured by normals to the equiluminous surfaces, lies in the plane of the emulsion perpendicular to the geometrical...
Page 159 - CK2 long, with very bright center, and not to be distinguished from the thousands of very small, round or oval nebulae found wherever the spirals are found. There is an unbroken progression from such minute objects up to the Great Nebula in Andromeda itself ; I see no reason to believe that these...
Page 389 - Journal, 43, 310, 1916. spond to each other, and that probably all the oxygen of the air owes its existence to plant life.1 That a similar production of oxygen has apparently not taken place on Venus suggests that some condition is wanting. Possibly a deficiency of water has prevented or hindered the freeing of oxygen through vegetation, or it may be that the exacting conditions for the origin of life have not been satisfied so that the existing atmosphere may consist of other permanent or semipermanent...
Page 260 - Va is the solar velocity. Table I gives the results of this computation for different spectral types and absolute magnitudes. In this case all stars with a space-velocity higher than 100 km have been omitted. TABLE I From Table I we see that for the giant stars the declination of the sun's apex shows a steady increase from +27° to +44°, which is in agreement with the results of several investigators who have determined its value from proper motions. This increase of the declination of the sun's...
Page 135 - Five of these have color-indices from 0.74 to 095 in excess of normal and seem to be involved in the nebula. The mean of the parallaxes of these five stars is 0^0095 ±0^006. This is therefore taken to be the parallax of the nebula, equivalent to a distance of 350 light years from the sun. The star BD+3i°643 is of special interest because it is apparently imbedded in the densest part of a diffuse, irregularly shaped nebula extending over the region surrounding this star. The photograph of this region...
Page 166 - There is probably an uncertain number of objects listed as "continuous" in which faint emission images are present and not recognized, but in every case of previously known emission on a continuous background, the slitless spectra show unmistakable irregularities in distribution of density. In view of the uncertainty, however, the method adopted is to list the nebulae as giving predominantly continuous or predominantly emission spectra, and to call attention in notes to combinations of characteristics....
Page 271 - Figure 7 are plotted the projections in the ry-plane of the velocities of the stars having space motions larger than 100 km relative to the origin. The effect of the selection of large proper motions relative to the sun instead of to our adopted origin is then insignificant, and we find that, whatever the spectral type or the absolute magnitude, if the velocity of a star is great there is an avoidance of the first quadrant of the...