The light-curves of the two large amplitude variable stars , R Scuti and AC Herculis , display irregular pulsation cycles with ’ periods ’ of 75 and 35 days , respectively .
We review the evidence that the observed time-series are generated by low dimensional chaotic dynamics .
In particular , a global flow reconstruction technique indicates that the minimum embedding dimensions are 4 and 3 , for R Sct and AC Her , respectively , whereas the fractal dimensions are inferred to be d _ { L } \approx 3.1 and 2.05 { \thinspace } { \raise 3.0 pt \hbox { $ { \scriptstyle < } $ } \kern - 6.0 pt \lower 1.1 pt% \hbox { $ { \scriptstyle \sim } $ } } { \thinspace } d _ { L } { \thinspace } { \raise 3.0 pt \hbox { $ { % \scriptstyle < } $ } \kern - 6.0 pt \lower 1.1 pt \hbox { $ { \scriptstyle \sim } $ } } { \thinspace% } 2.45 , respectively .
It thus appears that the dimensions of the dynamics themselves are also 4 and 3 .