Radio Planetary Nebulae in the Magellanic Clouds
  We report the extragalactic radio-continuum detection of 15 planetary nebulae
(PNe) in the Magellanic Clouds (MCs) from recent Australia Telescope Compact
Array+Parkes mosaic surveys. These detections were supplemented by new and high
resolution radio, optical and IR observations which helped to resolve the true
nature of the objects. Four of the PNe are located in the Small Magellanic
Cloud (SMC) and 11 are located in the Large Magellanic Cloud (LMC). Based on
Galactic PNe the expected radio flux densities at the distance of the LMC/SMC
are up to ~2.5 mJy and ~2.0 mJy at 1.4 GHz, respectively. We find that one of
our new radio PNe in the SMC has a flux density of 5.1 mJy at 1.4 GHz, several
times higher than expected. We suggest that the most luminous radio PN in the
SMC (N S68) may represent the upper limit to radio peak luminosity because it
is ~3 times more luminous than NGC 7027, the most luminous known Galactic PN.
We note that the optical diameters of these 15 MCs PNe vary from very small
(~0.08 pc or 0.32"; SMP L47) to very large (~1 pc or 4"; SMP L83). Their flux
densities peak at different frequencies, suggesting that they may be in
different stages of evolution. We briefly discuss mechanisms that may explain
their unusually high radio-continuum flux densities. We argue that these
detections may help solve the "missing mass problem" in PNe whose central stars
were originally 1-8 Msun. We explore the possible link between ionised halos
ejected by the central stars in their late evolution and extended radio
emission. Because of their higher than expected flux densities we tentatively
call this PNe (sub)sample - "Super PNe".
