Resolution requirements for simulating gravitational fragmentation using SPH
School of Physics & Astronomy, Cardiff University, 5 The Parade, Cardiff CF24 3YB, Wales, UK e-mail: David.Hubber@astro.cf.ac.uk
Received:
24
August
2005
Accepted:
1
December
2005
Jeans showed analytically that, in an infinite uniform-density isothermal
gas, plane-wave perturbations collapse to dense sheets if their wavelength, λ,
satisfies 
(where a is the isothermal sound speed and 
is the unperturbed density);
in contrast, perturbations with smaller λ oscillate about the uniform density
state. Here we show that Smoothed Particle Hydrodynamics reproduces these results
well, even when the diameters of the SPH particles are twice the wavelength of
the perturbation. Our simulations are performed in 3-D with initially settled (i.e.
non-crystalline) distributions of particles. Therefore there exists the seed noise for
artificial fragmentation, but it does not occur. We conclude that, although there may
be – as with any numerical scheme – “skeletons in the SPH cupboard”, a propensity to
fragment artificially is evidently not one of them.
Key words: stars: formation / methods: numerical / hydrodynamics / instabilities
© ESO, 2006