Showing papers in "Astrophysics and space science library in 1974"

Statistics of Supernovae

Abstract: The frequency of SNe is strongly dependent on the intrinsic properties of their parent galaxies. The present investigation is an attempt to determine within a clearly defined sample volume the SN frequency as a function of two principal parameters: the type and the luminosity (or mass) of the parent galaxy — which seem to control essentially the intrinsic SN rate. In this respect it is an extension and improvement of an earlier paper (Tammann, 1970), where only Sb and Sc galaxies could be considered. Available distances have become in the mean time sufficiently accurate within the sample volume considered, that it seems possible to use individual intrinsic luminosities for the sample galaxies. The distance scale is based throughout on a value of the Hubble constant of 55 (Sandage and Tammann, 1974), whereas the earlier paper used H 0=75 km s−1 Mpc−1. The other major change in the present paper is that it allows for a newly found selection effect of the observable number of SNe in inclined spiral galaxies.

Remarks on Outlying Supernovae and the Structure of Their Parent Galaxies

Abstract: Some supernovae have appeared at considerable radial distance, outside of the optical boundaries of their parent galaxies. This raises the important question from what kind of stellar population they have originated. This is a first, preliminary report on three typical cases.

Supernovae and their remnants

Abstract: Supernovae of type II must be related to rather massive stars. They appear to occur rather exclusively in the spiral arms of galaxies and this fact alone sets a lower limit of about 5 M⊙ to their main sequence mass. If we believe that all massive stars above some critical value become supernovae (and none below this value) the supernova rate would indicate masses in excess of 10 or 20 M⊙, the precise value depending on the particular choice of the luminosity function. Arguments of this type, however, do not take into account the possible dependence of stellar evolution on the presence of a binary system and other factors like rotation.

Formation of wisps in the Crab Nebula

Abstract: We discuss here a sequence of physical processes leading to a possible explanation of the formation of the ‘wisps’, well-known microfeatures visible inside the Crab Nebula. More generally we will be interested in the energetic correlation between the young pulsar NP0532 and the surrounding supernova remnant.