Ansae in Planetary Nebula
Saturn is not the only object to display ansae, as these features are common place in planetary nebula.
It is one of the most obvious structural properties or features among the planetary nebula and the bipolar planetaries are the ansae (singular; ansa), which in some ways look like ‘handles’.
It is often suggested to be caused by the phenomenon of multiple ejection of material from the central white dwarf star. Primarily, the shape and brightness variations are manifest by this star - often being a close binary or possibly even large planetary bodies.
Theoretically, the existence of such binaries would actually influence the flow of the nebulosity away from the nebulae, producing variations in torque/ angular momentum. In turn, this precesses the material into spirals, such as seen is commonplace southern planetaries like:-
NGC 3918 (The Blue Planetary) in Centaurus, NGC 5189 (The Spiral Planetary)/ NGC 4071 / MyCn18 [All in Musca]
These examples all have produced multiple groups ansae as seen within the imaged nebulosity.
Current understand of these mechanisms has lead to the production of multitudes of computer-generated planetaries - ans some explaination of planetary formation and gas outflows.
|