Resumen
Molecular clouds are highly structured. It is often asserted that highly turbulent gas produces the high-density inhomogeneities. Simulations following the behaviour of a single magnetosonic wave indeed showed the generation of large density contrasts which are associated with slow-mode waves. In these simulations the medium was treated as a single ideal plasma in which the gas is perfectly coupled with the magnetic field. However, the low ionisation fraction within molecular clouds implies that the gas and the magnetic field are actually weakly coupled and, thus, ambipolar resistivity becomes important. Using multifluid adaptive mesh magnetohydrodynamic simulations, we examine the effect of ambipolar resistivity on the generation of density perturbations. Our results show that it affects waves with wavelengths up to two orders of magnitude larger than the dissipation length scale, effectively inhibiting the generation of dense structures. This sets a lower limit on the size of dense cores of order 0.1 parsec.
