
%0 Journal Article
%A Bray, RJ 
%A Loughhead, RE 
%T The Lifetime of Sunspot Penumbra Filaments
%J Australian Journal of Physics
%D 1958/06/01
%V 11
%N 2
%P 185-190
%K 
%R https://doi.org/10.1071/PH580185
%U https://www.publish.csiro.au/paper/PH580185 
%X Twenty-seven photographs of a sunspot showing a particularly distinct filamentary structure are analysed in order to obtain an estimate of the lifetime of the penumbral filaments. The photographs have been selected from some 2400 taken over a period of 5 hr. Although the measurements are rendered somewhat uncertain by observational difficulties the results clearly indicate that some filaments remain identifiable for periods of the order of hours. 
