Abstract
Context
. Long-term H
α
variability provides a direct probe of the dynamical evolution of Be-star circumstellar disks, but interpreting these changes in terms of physical disk properties remains challenging.
Aims
. We explore the entropy–complexity (
H–C
) plane as a compact diagnostic to link changes in the H
α
emission-line morphology to the physical evolution of Be-star disks.
Methods
. We applied entropy and López–Ruiz–Mancini–Calbet complexity diagnostics to H
α
line profiles from a grid of viscous decretion disk (VDD) models and from time-resolved observations of the late-type Be star
β
Psc. We compared their respective evolutionary pathways in the
H–C
plane.
Results
. The star exhibits an abrupt excursion and a subsequent secular recovery in the
H–C
plane, associated with rapid changes in the disk mass and apparent inclination within the adopted framework, before returning to a spectroscopic state similar to that observed prior to the major disk event around 2007.
Conclusions
. The
H–C
diagram provides a simple diagnostic that is capable of tracing long-term structural evolution and rapid transitions in Be-star disks using the morphology of the H
α
line profile alone.