An extremely carbon-poor planetary nebula in the Small Magellanic Cloud

An optical and ultraviolet study is presented of object 28 of Sanduleak et al. (1978) in the SMC. This object is an extreme type of I PN which apparently has undergone all three stages of nuclear dredge-up together with an appreciable amount of convective envelope burning. Optical and UV data are well-represented by a model in which the central star has a temperature of 180,000 K and a radius of 0.09 solar radius. A nebular mass of 0.71 solar mass and a central star mass of 0.65-0.71 solar mass are inferred. The object apparently evolved from a massive progenitor with main-sequence mass greater than five solar masses, which underwent both second and third nuclear dredge-up and very efficient hot bottom burning.