The sharp decline in fractional ionization at is here associated with the distinction between starless and star-containing cores in the RMC, through changes in turbulent support. This concept has led us to perform a preliminary study of the chemical evolution of a collapsing cloud, in which the cloud can first collapse only along the magnetic field lines. As the collapse proceeds, the fractional ionization declines until a multidimensional collapse modulated by ambipolar diffusion ensues. We show that while the details of the chemistry are broadly similar to other comparable studies that have much cruder models of collapse, the specific nature of the collapse - in particular, the density at which multidimensional collapse becomes significant - should be indicated by chemical abundances.
© European Southern Observatory (ESO) 1998
Online publication: May 15, 1998