Long-duration simulations of the evolution of jet-driven molecular outflows

Free access article

Issue		A&A Volume 437, Number 2, July II 2005


Page(s)		517 - 524
Section		Interstellar and circumstellar matter
DOI		http://dx.doi.org/10.1051/0004-6361:20042253

A&A 437, 517-524 (2005)
DOI: 10.1051/0004-6361:20042253

Long-duration simulations of the evolution of jet-driven molecular outflows

R. Keegan and T. P. Downes

School of Mathematical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland
e-mail: turlough.downes@dcu.ie

(Received 26 October 2004 / Accepted 22 March 2005 )

Abstract
We use numerical simulations to examine the mass-velocity, m(v), and intensity-velocity, I(v), relations in jet-driven molecular outflows up to an age of 2300 yr. We find that the m(v) relation is a power-law, $m(v) \propto v^{-\gamma}$ , the exponent of which increases with time up to $\gamma \approx 1.6$ at $t \approx 1500$ yr. It then becomes roughly constant. This indicates that $\gamma$ does not evolve throughout the lifetime of a molecular outflow, at least in the context of the jet-driven model.

We also investigate the effect of long-period episodicity of the jet on the m(v) and I(v) relations. We find that, contrary to previous expectations, these relations are not significantly changed with the introduction of such variability into the jet.

Finally, we present a novel, and relatively simple, parallelisation method for the code used in these simulations. This gives an increase of roughly a factor of 4 in speed over standard methods, and allows the simulations presented here to be run fairly easily, even with modest computational resources.

Key words: hydrodynamics -- shock waves -- ISM: jets and outflows -- ISM: molecules

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