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NASA NTRS1971

The velocity and composition of supernova ejecta

In case of the Gum nebula, a pulsar - a presumed neutron star - is believed to be a relic of the supernova explosion. Regardless of the mechanism of the explosion, the velocity distribution and composition of the ejected matter will be roughly the same. The reimploding mass fraction is presumed to be neutron rich. The final composition is thought to be roughly 1/3 iron and 2/3 silicon, with many small fractions of elements from helium to iron. The termination of helium shell burning occurs because the shell is expanded and cooled by radiation stress. The mass fraction of the helium burning shell was calculated.

Colgate, S. A.↗
NASA NTRS1971

The early evolution of giant H II regions formed by supernova explosions

The evolution of a giant H II region, which cools after an initial ionization, is discussed. The discussion is applied to the Vela X and Tycho supernovae. Other giant H II regions might not be as easily detectable as the Vela X region. The Tycho region may be just detectable in the O(II) or O(III) optical lines or as a hole in the 21-cm emission line profiles, as is suggested in the data. These giant H II regions last appreciably longer than the continuum radio sources within them.

Kafatos, M. C.↗
NASA NTRS1972

Spectra of type I supernovae. I - Generalities. II - Interpretation of the spectra of Sn 1960 in NGC 4496 from 8 to 20 days after the maximum of luminosity.

In the late stages of type I supernovae evolution (t greater than 50 days) the spectrum is without doubt an emission line spectrum, but in the early stages it is difficult to tell if an emission line spectrum is observed, or a continuum spectrum modified by the overlaying absorption formed in the outer layers. The mechanism of formation of the observed spectra, the physical conditions in the shell, different possible sources of heating of the shell, identification of the lines, and theoretical computations of the line intensities are discussed. An attempt is made to interpret the set of spectra assuming that a spectrum of widely broadened emission lines truncated by an overlaying absorption is seen. The absorption spectrum is first studied. An identification for the emission lines is proposed, and their intensity on the observed spectra is tentatively estimated. These identifications have to be justified by the theoretical computations of a model of the shell.

Gordon, C.↗
NASA NTRS1973

X-ray observations of the supernova remnants Cas A and Tycho

A rocket-borne multilayer multianode proportional counter observation of Cas A and Tycho supernovae remnants shows no evidence for periodic emissions in the period range from 1 millisecond to 13 seconds. Comparison of inferred incident photon spectra and electromagnetic flux intensity as a function of energy rules out simple synchrotron or isothermal models for both Cas A and Tycho. It is concluded that there must still be a contemporary source of energy in the source region to connect the radio and X-ray emission from these remnants.

Brisken, A. F.↗