Species of cosmic matter.

Abstract

view Abstract Citations (3) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Species of cosmic matter. Zwicky, F. Abstract It has been known for a long time that different species of stars and of matter in general are found in various locations of the universe such as in the neighborhood of the sun, in galactic and in globular clusters, in spiral and in elliptical galaxies and so on. Different species of the common stars as well as special objects such as certain variables, novae and supernovae, B-emission stars, Wolf-Rayet stars, emission nebulae, gas and dust clouds often seem to be grouped in both real space and in "velocity space."In order to characterize the totality of species in any location one has generally resorted to the representation of stars in Hertzsprung-Russell diagrams or more generally in color diagrams which give the spectral type or color as functions of the absolute or apparent magnitudes. Also the idea has been advanced that fundamentally there are only two types of populations, I and II, and mixtures thereof. In contradistinction to these views, a morphological study of the known large-scale interactions of matter suggests I) celestial objects can organically be arranged only in multidimensional spaces of representation rather than in two dimensional diagrams. Absolute magnitude, color and spectral characteristics (more than one), period and amplitude of light variation, flare characteristics, large-scale magnetic and electric fields, close association with other bodies, dust and gases must be introduced as the independent coordinates in a representative space. 2) There exists a great number of different stellar and material populations. The morphological conclusion I) is now being checked by a thorough study of the characteristics of especially the fainter stars in galactic clusters such as the Hyades. While much work will be necessary to establish true morphological arrays of stars in lieu of the two dimensional diagrams, decisive observational evidence is already at hand that the concepts of stellar populations I and II are entirely inadequate. A most striking example of the coexistence of at least three distinct stellar populations was obtained on excellent photographs with the ~oo-inch telescope of the Whirlpool nebula. These populations are characterized as follows: a) blue patches showing resolved blue stars (supergiants), b) red patches which are not resolved, c) very extended smooth blue patches which show no resolution into stars or groups of stars whatsoever and which are particularly prominent in the outs~irts of the companion nebula NGC 5195 and along the faint broad spiral arm which connects NGC 5194 and 5195. As we shall proceed to include ever fainter stars in our population studies we may expect to discover a great number of basic populations. The facts already known at present, suffice to indicate that any evolutionary theories based on the assumption of two-dimensional population diagrams are likely to be lacking any realistic foundation. Likewise, any distance determinations among distant galaxies which are based on the assumption of only two stellar populations and which rely on such criteria as luminosities of brightest stars, clusters of stars and variable stars will be found to be equally unrealistic. In connection with these investigations a simple but powerful method of composite "red" and "blue" photography has been developed which on the resulting plates shows extended blue and red objects respectively lighter and darker than the sky background while blue and red stars appear respectively as dark points with light rings around them or simply as dark points. Mount Wilson and Palomar Observatories, Carnegie Institution of Washington, Calsfornia Institute of Technology, Pasadena, Calsf. Publication: The Astronomical Journal Pub Date: December 1953 DOI: 10.1086/106879 Bibcode: 1953AJ.....58..237Z full text sources ADS |