Bibcode
DOI
Cuesta, L.; Phillips, J. P.
Referencia bibliográfica
The Astronomical Journal, Volume 118, Issue 6, pp. 2929-2939.
Fecha de publicación:
12
1999
Número de citas
12
Número de citas referidas
10
Descripción
The planetary nebula NGC 2392 possesses an extremely unusual
spectrokinematic morphology, characterized by several strange and
elusive structures. In this paper, extensive narrowband imaging of the
source is used to investigate the shell excitation structure, while [O
III] and [S II] images are ratioed to provide fully sampled mapping of
electron density and temperature. As a result, we are able to confirm
the presence of low densities in the various filamentary structures, an
appreciable radial decrease in density in the outer shell, and finally,
a probable regime of higher shell densities at the interface of the
bright inner shell and lower intensity outer halo. Although temperatures
are more uniform, we also find evidence for a significant temperature
enhancement close to the inner-outer shell interface, and it is proposed
that both anomalies (in density and temperature) arise in a postshock
cooling regime. Finally, present imaging and prior spectroscopy are used
to construct a revised model of the source, in which it is argued that
the outer filamentary structure occupies a disklike regime, congruent
with the principal plane of the outer spheroid. Individual filaments
arise from low-excitation density contrasts, created through the
interaction between the outer shell and a precessing jet.