Jets and the shaping of the giant bipolar envelope of the planetary nebula KjPn 8

Abstract

A hydrodynamic model involving cooling gas in the stagnation region of a collimated outflow is proposed for the formation of the giant parsec-scale bipolar envelope that surrounds the planetary nebula KjPn 8. Analytical calculations and numerical simulations are presented to evaluate the model. The envelope is considered to consist mainly of environmental gas swept-up by shocks driven by an episodic, collimated, bipolar outflow. In this model, which we call the ``free stagnation knot'' mechanism, the swept-up ambient gas located in the stagnation region of the bow-shock cools to produce a high density knot. This knot moves along with the bow-shock. When the central outflow ceases, pressurization of the interior of the envelope stops and its expansion slows down. The stagnation knot, however, has sufficient momentum to propagate freely further along the axis, producing a distinct nose at the end of the lobe. The model is found to successfully reproduce the peculiar shape and global kinematics of the giant bipolar envelope of KjPn 8.

20 pages + 8 figures (in 1 tar-file 0.67 Mb)

References in corpus (4)

• GRAPESPH with Fully Periodic Boundary Conditions: Fragmentation of Molecular Clouds
• Outflow collimation in young stellar objects
• Jet cocoons and the formation of Narrow Line Clouds in Seyfert galaxies
• High Resolution CO Imaging of the Molecular Disk around the jets in KjPN 8

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• Collimated Fast Wind in the Pre-Planetary Nebula CRL 618
• Multiple Fast Molecular Outflows in the PPN CRL 618
• Kinematical Analysis of a Sample of Bipolar Planetary Nebulae
• The expansion proper motions of the extraordinary giant lobes of the planetary nebula KjPn 8 revisited
• Gas physical conditions and kinematics of the giant outflow Ou4