Bimodality versus multimodality - Do fragmentation theories support a bimodal IMF?

The origin of the initial mass function (IMF) for field stars was investigated. The IMF was computed using the nonlinear approach developed by Ferrini et al. (1983) and Fleck (1983), taking into account the simultaneous presence of various instability crieria in the definition of the critical mass for fragmentation; the physical quantities that define the critical mass for fragmentation were constrained by using the results of a large sample of observations. A comparison of the computed IMF with the observed IMF showed that, two basic properties of the observed IMF can be reproduced: the position of the maximum, the curvature, and the flattening of the distribution at small masses; and the power law that describes the behavior of masses larger than the characteristic mass. In some of the computed IMFs, small departures from a smooth monotonic trend were found, indicating that the nature of the IMF reflects a multimodal, rather than a bimodal, character.