
%0 Journal Article
%A Ivanov, VP 
%A Stankevich, KS 
%T Nonstationary Phenomena in the Radiation of Young Supernova Remnants
%J Australian Journal of Physics
%D 1987/12/01
%V 40
%N 6
%P 801-814
%K 
%R https://doi.org/10.1071/PH870801
%U https://www.publish.csiro.au/paper/PH870801 
%X The time variation of the radio emission from the supernova remnants Cassiopeia A, the Crab Nebula and Tycho Brahe (SN 1572) is investigated. There is a frequency dependence on the rate of decrease in the flux density of Cassiopeia A for the period 1957 to 1984. The (positive) spectral index has a secular decrease and also, for frequencies above 320 MHz, slight oscillations with a six-year period. The radio emission from the Crab Nebula was constant from 1953 to 1975 but has since decreased accompanied by a change in spectral index. The average decrease of the flux density of SN 1572 from 1963 to 1983 was 0·52% per year, close to the value predicted for adiabatic expansion. 
