Articles written in Journal of Astrophysics and Astronomy
Volume 14 Issue 2 June 1993 pp 65-82
The various and hitherto partially unsolved problems relative to the origin of bipolar jets or highly collimated fast outflows in planetary nebulae are reviewed within the framework of a stationary magnetohydrodynamic model.
In order to explain the observations of high polar velocities and the presence of polar blobs or knots in planetary nebulae, theoretical models are proposed taking into account both a large scale azimuthal magnetic field and an anisotropic turbulent velocity field.
The models predict equatorial-to-polar density ratios which are rather small, in the range 2 to 3. Conversely, the polar-to-equatorial velocity contrasts are higher, with typical values upto 10. Thus the
We point out, therefore, that the bipolar jets have to be considered as a transient aspect of a very complex phenomenon. The model can be applied to objects such as He 2–104 or Mz3, M2–9.
Volume 40 | Issue 3
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