THE ONSET OF CHAOS IN PULSATING VARIABLE STARS

Анотація

Random changes in pulsation period
occur in cool pulsating Mira variables, Type A, B,
and C semiregular variables, RV Tauri variables, and
in most classical Cepheids. The physical processes
responsible for such fluctuations are uncertain, but
presumably originate in temporal modifications of the
envelope convection in such stars. Such fluctuations
are seemingly random over a few pulsation cycles of
the stars, but are dominated by the regularity of the
primary pulsation over the long term. The magnitude
of stochasticity in pulsating stars appears to be linked
directly to their dimensions, although not in simple
fashion. It is relatively larger in M supergiants, for example,
than in short-period Cepheids, but is common
enough that it can be detected in visual observations
of the stars, as demonstrated by the example of Delta
Cephei. Although chaos was discovered in pulsating
stars 80 years ago, detection of its general presence in
the group has only been possible in recent studies.