  We present the initial results from the Infrared Array Camera (IRAC) imaging
survey of planetary nebulae (PN). The IRAC colors of PN are red, especially
when considering the 8.0 micron band. Emission in this band is likely due to
contributions from two strong molecular hydrogen lines and an [Ar III] line in
that bandpass. IRAC is sensitive to the emission in the halos as well as in the
ionized regions that are optically bright. In NGC 246, we have observed an
unexpected ring of emission in the 5.8 and 8.0 micron IRAC bands not seen
previously at other wavelengths. In NGC 650 and NGC 3132, the 8.0 micron
emission is at larger distances from the central star compared to the optical
and other IRAC bands, possibly related to the molecular hydrogen emission in
that band and the tendency for the molecular material to exist outside of the
ionized zones. In the flocculi of the outer halo of NGC 6543, however, this
trend is reversed, with the 8.0 micron emission bright on the inner edges of
the structures. This may be related to the emission mechanism, where the
molecular hydrogen is possibly excited in shocks in the NGC 6543 halo, whereas
the emission is likely fluorescently excited in the UV fields near the central
star.

Astrophysics