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| Paper: |
FLIERs as Stagnation Knots from Partially Collimated Outflows |
| Volume: |
199, Asymmetrical Planetary Nebulae II: From Origins to Microstructures |
| Page: |
413 |
| Authors: |
Steffen, Wolfgang; López, José Alberto |
| Abstract: |
We propose a new model for the formation of fast, low-ionization emission regions (FLIERs) in planetary nebulae that is able to account for many of their attendant characteristics and circumvent the problems on the collimation/formation mechanisms found in previous studies. In this model, FLIERs are formed in the stagnation zone of partially collimated stellar winds with reduced momentum flow along the axis. A concave bow-shock structure is formed due to the lack of momentum flow along the axis of a midly bipolar stellar wind. The stagnation knots are formed when the shocked environment medium accumulates at the apex of the outer shell and is compressed to a dense knot in the concave section of the bow-shock. We present two-dimensional hydrodynamic simulations of the formation of a stagnation knot and compare the resultant dynamical properties with those of FLIERs in planetary nebulae. |
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