  Recent high-resolution studies of the L1544 protostellar core by Tafalla et
al. and Williams et al. reveal the structure and kinematics of the gas. The
observations of this prestellar core provide a natural test for theoretical
models of core formation and evolution. Based on their results, the above
authors claim a discrepancy with the implied infall motions from ambipolar
diffusion models. In this paper, we reexamine the earlier ambipolar diffusion
models, and conclude that the L1544 core can be understood to be a magnetically
supercritical core undergoing magnetically diluted collapse. We also present a
new model specifically designed to simulate the formation and evolution of the
L1544 core. This model, which uses reasonable input parameters, yields mass and
radial density distributions, as well as neutral and ion infall speed profiles,
that are in very good agreement with physical values deduced by observations.
The lifetime of the core is also in good agreement with prestellar core
lifetimes estimated from statistics of an ensemble of cores. The observational
input can act to constrain other currently unobserved quantities such as the
degree of ionization, and the background magnetic field strength and
orientation near the L1544 core.
