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32. Theoretical problems of discrete radio sources

Published online by Cambridge University Press:  14 August 2015

J. L. Greenstein
J. L. Greenstein*
Affiliation:
Mount Wilson and Palomar Observatories, California, U.S.A.

Extract

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The range of theoretical problems connected with the discrete sources is very large. It is convenient to distinguish between the normal and abnormal radio-frequency emitters that have quite different energy outputs per unit volume. Since the estimates by Minkowski and Greenstein [1] there has been considerable progress in the identification of these objects and in the provision of quantitative data about them. Table 1 includes revised estimates of the total luminosity, L, the emitting volume, V, and the luminosity per cubic parsec, J. Here L has been obtained by multiplying the observed power at 100 Mc./s. by an effective band-width of 500 Mc./s. and using the newly estimated distances. J is expressed in units of the total energy output of the sun (= 3·82 × 1026 watt) per cubic parsec. The figure for the Galaxy and M31 is considerably higher than that given by Baldwin in this symposium, since I have not revised the estimate of the emitting volume from the original paper by Minkowski and Greenstein. If most of the emission comes from a larger galactic halo the specific luminosity, J, for the Galaxy and M31 should be considerably reduced. For certain of the extra-galactic sources it is not certain whether the volume of the whole nebula, or only of the parts now in collision (or peculiar in nature, like the jet in M87) should be used in computing the specific emissivity, J. In Table 1, two values are then given.

Type
Part II: Point Sources: Individual Study and Physical Theory
Information
Symposium - International Astronomical Union , Volume 4: Radio Astronomy , 1957 , pp. 179 - 191
Copyright
Copyright © Cambridge University Press 1957 

References

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