Compact planetary nebulae in the Galactic disk: Analysis of the central stars

Central Stars of Planetary Nebulae in the Galactic Bulge

Context. Optical high-resolution spectra of five central stars of planetary nebulae (CSPN) in the Galactic bulge have been obtained with Keck/HIRES in order to derive their parameters. Since the distance of the objects is quite well known, such a method has the advantage that stellar luminosities and masses can in principle be determined without relying on theoretical relations between both qua...

Abundance gradients in the outer galactic disk from planetary nebulae

Radial abundance gradients of the element ratios O/H, Ne/H, S/H, and Ar/H are determined on the basis of a sample of disk planetary nebulae. The behaviour of the gradients at large distances from the galactic centre, R > R0 = 7.6 kpc, is emphasized. It is concluded that the derived gradients are consistent with an approximately constant slope in the inner parts of the Galaxy, and some flattenin...

Stars and Planetary Nebulae in the Galactic Bulge

Binarity of Central Stars of Planetary Nebulae

I list the 16 planetary nebulae (PNe) known to contain closebinary nuclei, and show that the nebulae generally have axisymmetric structures, including elliptical, bipolar, or ring morphologies. The orbital periods range from 2.7 hr to 16 days, and close binaries constitute ≈10% of all central stars. Since the known binaries were found mainly from photometric variability, which depends on heatin...

Spectral Analysis of Central Stars of Planetary Nebulae

Spectral analysis by means of NLTE model atmospheres has presently arrived at a high level of sophistication. High-resolution spectra of central stars of planetary nebulae can be reproduced in detail from the infrared to the X-ray wavelength range. In the case of LSV+46◦21, the exciting star of Sh 2−216, we demonstrate the state-of-the-art in the determination of photospheric properties like, e...