TY  - THES
A1  - Todt, Helge
T1  - Hydrogen-deficient central stars of planetary nebulae
Y1  - 2009
DO  - 10.23689/FIDGEO-12
PB  - Univ. Potsdam
N2  - Central stars of planetary nebulae are low-mass stars on the brink of their final evolution towards white dwarfs. Because of their surface temperature of above 25,000 K their UV radiation ionizes the surrounding material, which was ejected in an earlier phase of their evolution. Such fluorescent circumstellar gas is called a "Planetary Nebula". About one-tenth of the Galactic central stars are hydrogen-deficient. Generally, the surface of these central stars is a mixture of helium, carbon, and oxygen resulting from partial helium burning. Moreover, most of them have a strong stellar wind, similar to massive Pop-I Wolf-Rayet stars, and are in analogy classified as [WC]. The brackets distinguish the special type from the massive WC stars.
UR  - http://hdl.handle.net/11858/00-1735-0000-0001-308D-8
ER  -