منابع مشابه
Binary Central Stars of Planetary Nebula
Only a handful of binary central stars of planetary nebulae (PNe) are known today, due to the difficulty of detecting their companions. Preliminary results from radial velocity surveys, however, seem to indicate that binarity plays a fundamental, rather than marginal role in the evolution of PNe and that the close binary fraction might be much larger than the currently known value of 10-15%. In...
متن کاملMartian double ring basins: New observations
Eighteen previously unknown martian basins have been detected on Viking photographs. The smallest basins have diameters 50 to 100 km less than the smallest known basins on Mercury or the moon. On the latter two planets and the earth, basin morphology varies with increasing diameter: central peak (CP) basins have both central peaks and fragmentary peak rings; peak ring (PR) basins have only conc...
متن کاملA New Wolf - Rayet Star and its Ring Nebula : PCG 11
In a search for new Galactic planetary nebulae from our systematic scans of the AngloAustralian Observatory/United Kingdom Schmidt Telescope (AAO/UKST) Hα survey of the Southern Galactic Plane, we have identified a Population I Wolf-Rayet star of type WN7h associated with an unusual ring nebula that has a fractured rim. We present imagery in Hα, the 843-MHz continuum from the Molonglo Observato...
متن کاملA New Look at the Evolution of Wolf-rayet Central Stars of Planetary Nebula
On the basis of recent observational evidence and new theoretical results, we construct a speculative scenario for the evolution of Wolf-Rayet central stars of planetary nebula. Although single star evolutionary calculations have recently succeeded in reproducing the composition of these objects, it is clear from the latest infra-red observations that a new perspective has to be adopted: the si...
متن کاملThe Element Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars
We review the observed properties of extremely hot hydrogen-deficient post-AGB stars of spectral type [WC] and PG1159. Their H-deficiency is probably caused by a (very) late heliumshell flash or a AGB final thermal pulse, laying bare interior stellar regions which are usually kept hidden below the hydrogen envelope. Thus, the photospheric element abundances of these stars allow to draw conclusi...
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ژورنال
عنوان ژورنال: Astronomische Nachrichten
سال: 1897
ISSN: 0004-6337,1521-3994
DOI: 10.1002/asna.18971431707