Numerical hydrodynamic simulations of jet-driven bipolar outflows

Smith, M.D. and Suttner, G. and Yorke, H.W. (1997) Numerical hydrodynamic simulations of jet-driven bipolar outflows. Astronomy and Astrophysics, 323 (1). pp. 223-230. ISSN 0004-6361. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Abstract

The jet model for protostellar outflows is confronted with the constraints imposed by CO spectroscopic observations. From three dimensional simulations of a dense molecular medium being penetrated by a denser molecular jet, we simulate line profiles and construct position-velocity diagrams for the (low-J) CO transitions. We find (1) the profiles imply power law variation of integrated brightness with velocity over a wide range of velocities, (2) the velocity field resembles a 'Hubble Law' and (3) a hollow-shell structure at low velocities becomes an elongated lobe at high velocities. Moreover, the leading bow shock produces strong forward motion of the cool gas rather than the expected lateral expansion. We are thus able to satisfy the Lada and Fich (1996) criteria, employing NGC 2264G as an example. Deviations from the simple power law dependence of integrated brightness versus velocity occur at high velocities in our simulations. The curve first dips to a shallow minimum and then rises rapidly and peaks sharply. Reanalysis of the NGC 2264G and Cepheus E data confirm these predictions. We identify these two features with a jet-ambient shear layer and the jet itself. A deeper analysis reveals that the power-law index is an indicator of the evolutionary stage: a profile steepens with time. Also, the CO excitation temperature changes along the bow walls and thus a CO line intensity does not directly yield the mass distribution, as often assumed. Instead, the CO emission is enhanced near the excitation peaks.

Item Type: Article
Uncontrolled keywords: Hydrodynamics, Infrared: interstellar: lines, ISM: jets and outflows, ISM: molecules, Shock waves
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Giles Tarver
Date Deposited: 11 Aug 2015 10:32 UTC
Last Modified: 12 Aug 2015 16:05 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50151 (The current URI for this page, for reference purposes)
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