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Published April 15, 1939 | public
Journal Article Open

On the theory and observation of highly collapsed stars

Zwicky, F.

Abstract

The investigation presented here falls into two parts. In the first part (Sections A to H) the general relativistic solution given by Schwarzschild of the problem of a homogeneous sphere of constant density is discussed. For every given density a characteristic mass Ml exists, for which the pressure in the center of the sphere becomes infinite, and for which the velocity of light in the same point becomes equal to zero. In the case of collapsed neutron stars. Ml is of the order of a large stellar mass. The effective mass and the gravitational energy of the sphere are determined as functions of its proper mass. Equations are developed which express the velocity and the wave-length of light as functions of the distance from the center of the sphere. The characteristic mass Ml of collapsed neutron stars is expressed in terms of the charge and mass of the electron and the proton and the universal gravitational constant. Some possible relations of the results obtained with recent cosmological theories are pointed out. The second part of this paper deals with the possibility of actually observing the formation of collapsed neutron stars. The hypothesis is examined that supernova outbursts are caused by the formation of neutron stars. A number of reasons are advanced which make this hypothesis attractive. From the data which were obtained from numerous observations of the bright supernova (1937) in the extragalactic spiral IC 4182, a number of consequences of the neutron star hypothesis are developed. In particular the redshift in the spectrum of the supernova IC 4182 is interpreted as a gravitational redshift. On this interpretation it follows that some of the physical characteristics of the central star of a supernova one year after maximum brightness are (in order of magnitude) as follows: radius 100 km, average density 10^12 g/cm^3 and effective surface temperature greater than 5×10^6 degrees. The light curves, the spectra and the total generation of energy in supernovae are discussed in the light of the neutron star hypothesis.

Additional Information

©1939 The American Physical Society. Received 7 March 1939. My thanks are due to Professor R. C. Tolman, in discussions with whom many of the results given in the first part of this paper were derived, and to Drs. Baade and Minkowski of the Mt. Wilson Observatory in collaboration with whom all of the observational data on supernovae were critically examined on numerous occasions.

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