Abstract
The central stars of planetary nebulae are known to possess ionized stellar winds with mass loss rates of about 10-8Msunyr-1 and velocities of ≡2000 km s-1. This wind is expected to be fully ionized and it should be a source of free-free radiation. In most cases, the radio flux expected is below detectability for a reasonable integration time even in the best radio telescopes. The authors selected four favorable candidates: NGC 2392, NGC 40, NGC 6543, and NGC 6302 for a radio continuum search. These planetary nebulae were observed using the VLA. The authors were not successful in detecting radio continuum from the stellar winds of their central stars, but they obtain upper limits for the mass loss rates of 3×10-7, 2×10-6, 1×10-6, and 2×10-5Msunyr-1, respectively.
