Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
J.M. Winters, T. Blöcker, K.-H.
Hofmann, and G. Weigelt:
Interpreting the evolving clumpy shell
structure of IRC+10216 in terms of time dependent dust shell models
in
Planetary Nebulae: Their Evolution and Role in the Universe ,
IAU Symp. 209, Canberra, Australia, November 19-23, 2001,
M. Dopita, S. Kwok, R. Sutherland (eds.), Astron. Soc. Pac., v.209,
p.127 (2003)
Abstract.
The prototypical dust enshrouded carbon Mira IRC+10216 is known to
exhibit intrinsic structural changes on a time scale of the order of 10
yr as
revealed, e.g., by CO infrared line profiles,
its infrared light curves,
or by high spatial resolution monitoring in the
infrared. In particular, the light curves obtained over 35 yr
indicate a possible
periodicity on a ~20 yr time scale, which suggests that a recurrent
phenomenon might lead to the observed variations in the CO first
overtone
line profiles and the clumpy spatial structure.
Such multi-periodicity time scales, which correspond to several
(~10) pulsation periods of the star, are predicted by
consistent hydrodynamical models which include a proper treatment of
dust formation.
In these models discrete dust layers
form on a time scale which is longer than the typical
pulsation period of AGB stars (Fleischer et al.\ 1995).
In the high spatial resolution images of IRC+10216
(Osterbart et al. 2000)
several components can be identified, whose structure and brightness
evolve considerably within only a few years.
To shed some light on this evolution,
we apply a spherically symmetric, time-dependent dust shell model
which consistently describes the coupled system of hydrodynamics,
chemistry, dust formation and radiative transfer
(Winters et al. 2000)
and confront the kinematics and brightness variations
predicted by this model with the high spatial resolution observations
of IRC+10216.