Jm. Winters et al., CIRCUMSTELLAR DUST SHELLS AROUND LONG-PERIOD VARIABLES .2. THEORETICAL LIGHTCURVES OF C-STARS, Astronomy and astrophysics, 290(2), 1994, pp. 623-633
Theoretical lightcurves of long-period and Mira variables are presente
d. Based on dynamical models of circumstellar dust shells (CDS), which
include time-dependent hydrodynamics and a detailed treatment of the
processes of formation, growth and evaporation of carbon grains, frequ
ency-dependent radiative transfer calculations have been carried out w
hich yield the synthetic infrared lightcurves of these dust shell mode
ls. It turns out that the discrete structure of the CDS due to the per
iodic formation of new dust layers decisively influences the shape of
the lightcurves by producing e.g. intermediate extrema. This is demons
trated in detail for one model. Furthermore, dust shell models are pre
sented whose lightcurves exhibit the superposition of two different os
cillations: The oscillation with the period of the interior pulsation
is superposed by an oscillation with a longer period which is produced
by the dynamical structure of the CDS. Similar features are present i
n observed lightcurves, which indicates that our, nevertheless prelimi
nary, modelling approach shows promise for interpreting the optical ap
pearance of Miras and long-period variables.