We present thermal-infrared images of three extreme bipolar objects , M 2-9 , Mz 3 , and He 2-104 .
They are bipolar planetary nebulae with bright central stars and are thought to be powered by symbiotic binary systems .
The mid-infrared images spatially resolve the spectral energy distributions of the central engines from the surrounding nebulae .
A warm dust component of several hundred degrees can account for the core emission , while a cooler component of \sim 100 K produces the more extended emission from the bipolar lobes .
In every case , the dust mass for the unresolved core region is orders of magnitude less than that in the extended lobes , raising doubts that the hypothetical disks in the core could have been responsible for pinching the waists of the nebulae .
We find total masses of roughly 0.5–1 M _ { \sun } in the nebulae of M 2-9 and Mz 3 , requiring that this material was donated by intermediate-mass progenitor stars .
The mass of He 2-104 ’ s nebula is much lower , and any extended emission is too faint to detect in our images .
Extended dust emission is detected around both M 2-9 and Mz 3 , in both cases resembling the distribution of ionized gas .
Our images of Mz 3 have the highest signal-to-noise in the extended polar lobes , and we show that the fairly uniform color temperature derived from our images can explain the 110 K dust component that dominates the far-infrared spectral energy distribution .
In the case of Mz 3 , most of the mass traced by dust is concentrated at high latitudes , and we note possible evidence for grain destruction in shocks indicated by an anticorrelation between [ Fe ii ] and dust emission .
Except for these regions with enhanced [ Fe ii ] emission , the dust continuum closely resembles the distribution of ionized gas .