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Astron. Astrophys. 364, 318-326 (2000)

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On the matter entrainment by stellar jets and the acceleration of molecular outflows

M. Micono 1,2, G. Bodo 1, S. Massaglia 2, P. Rossi 1 and A. Ferrari 2

1 Osservatorio Astronomico di Torino, Viale Osservatorio 20, 10025 Pino Torinese, Italy
2 Dipartimento di Fisica Generale dell'Università, Via Pietro Giuria 1, 10125 Torino, Italy

Received 29 June 2000 / Accepted 8 September 2000


We study, by numerical simulations, the entrainment process in a supersonic, radiative jet flow, during the evolution of Kelvin-Helmholtz instabilities, in the context of the the acceleration problem of molecular bipolar outflows observed in Giant Molecular Clouds. Our results show that a large fraction of the initial jet momentum can be transferred to the ambient medium by this process. We therefore analyze in detail the instability evolution and compare some of the main observational properties of molecular outflows with those of the entrained material that we observe in our simulations. In particular, we find a good agreement for the mass vs. velocity distribution and for the outflow collimation structure, especially when a light jet is moving into a denser ambient medium. This is probably the case for (obscured) optical jets driving powerful molecular outflows in the denser environment of the inner regions of molecular clouds.

Key words: hydrodynamics – instabilities – stars: early-type – ISM: jets and outflows

Send offprint requests to: M. Micono

© European Southern Observatory (ESO) 2000

Online publication: December 15, 2000