The case of the fastest stellar wind in central stars of planetary nebulae

Abstract

An exceptionally fast wind (8500 km/s) was suggested to occur in the central star of the planetary nebula K1-16, belonging to the class of the PG 1159 H-deficient pre-white dwarfs. To ascertain the reality of such a fast wind this star has been observed with the HST telescope using the GHRS in the zone of theCIV 155.0 nm doublet. The HST data and tests made using synthetic stellar spectra support the existence of a stellar wind with a terminal velocity of 3800 km/s and a mass loss rate lower thanM<2 · 10^‑11M_⊙ per year. Possibly it is no longer the fastest stellar wind so far observed but it is still among the fastest.