Central stars of planetary nebulae in SDSS and IPHAS

Abstract

Space densities and birthrates of Planetary Nebulae (PNe) are highly uncertain. A large range of formation rates has been derived by different studies, which has led to contradicting ideas for the final evolutionary phases of low and intermediate mass stars. We started a project to deduce a birthrate using a sample of PNe within 2 kpc. The central stars will be identified in the PNe fields by their photometric colours and then used to establish improved distance estimates. To facilitate this we have created grids of photometric colours which are used to constrain stellar parameters. Our study has concentrated on PNe in SDSS and the INT Photometric Hα Survey (IPHAS) so far. IPHAS is a nearly complete northern galactic plane survey in Hα, r' and i' bands. Many previously unknown PNe have been discovered with IPHAS. We investigate implications of a more complete local sample on PN birthrate estimates.