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Non-convergence of the critical cooling timescale for fragmentation of self-gravitating discs

Published online by Cambridge University Press:  10 November 2011

Farzana Meru
Affiliation:
School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK email: farzana@astro.ex.ac.uk Institut für Astronomie und Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
Matthew R. Bate
Affiliation:
School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK email: farzana@astro.ex.ac.uk
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Abstract

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We carry out a resolution study on the fragmentation boundary of self-gravitating discs. We perform three-dimensional Smoothed Particle Hydrodynamics (SPH) simulations of discs to determine whether the critical value of the cooling timescale in units of the orbital timescale, βcrit, converges with increasing resolution. Using particle numbers ranging from 31,250 to 16 million (the highest resolution simulations to date) we do not find convergence. Instead, fragmentation occurs for longer cooling timescales as the resolution is increased. These results certainly suggest that βcrit is larger than previously thought. However, the absence of convergence also questions whether or not a critical value exists. In light of these results, we caution against using cooling timescale or gravitational stress arguments to deduce whether gravitational instability may or may not have been the formation mechanism for observed planetary systems.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

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