On the discovery of an enormous ionized halo around the hot DO white dwarf PG 1034+001

Abstract

The discovery of the largest known planetary nebula on the sky surrounding the DO white dwarf PG 1034+001 with an apparent diameter of about 2°, corresponding to a linear diameter of 3.5–7.0 pc at the likely distance of 100–200 pc, has been reported by Hewett et al. ([CITE]). A careful inspection of available sky survey data has now shown that this planetary nebula, Hewett 1, is surrounded by an elliptical emission shell with an apparent diameter of ° ( at ). A further emission structure, detected northeast of the central star, may indicate another shell with a size of 10° 16°. From presently available observational data we do not have indications revealing whether the emission arises from material ejected from PG 1034+001 or from ionized ambient ISM. Improved proper motion data combined with radial velocity and distance data from the literature have enabled us to derive a Galactic orbit for the central star PG 1034+001. Its thin disk orbit and the morphology of the first halo suggest that the nebula is in an advanced stage of interaction with the interstellar medium.