Pt. Boyd et al., NONPERIODIC VARIATIONS IN ASTROPHYSICAL SYSTEMS - INVESTIGATING FREQUENCY EVOLUTION, The Astrophysical journal, 445(2), 1995, pp. 861-871
We present a method related to the wavelet transform, the Gabor transf
orm, for investigating astronomical time series containing nonconstant
frequencies. Instances in which such data sets may arise include vari
able star light curves, numerical studies of the gravitational three-b
ody problem, X-ray binaries, and signals from more exotic objects such
as planets around pulsars and mass infall from accretion structures o
nto compact objects. As an illustration of its power, we apply the tec
hnique to a numerical data set of a gravitational three-body interacti
on and to photometry of the rapidly oscillating peculiar A star HD 604
35. In the three-body example, the method provides an insightful short
hand that allows for the determination of episodes where the system be
haves as two nearly Keplerian orbits. For HD 60435, the power in the m
ain frequency exhibits unusual evolution over the duration of the obse
rvation.