摘要：Recently, a class of non-truncated, radially anisotropic models (the so-called
f(ν)-models),
originally constructed in the context of violent relaxation and modelling of elliptical
galaxies, has been found to possess interesting qualities in relation to observed and
simulated globular clusters. In view of new applications to globular clusters, we improve
this class of models along two directions. To make them more suitable for the description
of small stellar systems hosted by galaxies, we introduce a “tidal” truncation by means of
a procedure that guarantees full continuity of the distribution function. The new
fT(ν)-models are
shown to provide a better fit to the observed photometric and spectroscopic profiles for a
sample of 13 globular clusters studied earlier by means of non-truncated models;
interestingly, the best-fit models also perform better with respect to the radial-orbit
instability. Then, we design a flexible but simple two-component family of truncated
models to study the separate issues of mass segregation and multiple populations. We do
not aim at a fully realistic description of globular clusters to compete with the
description currently obtained by means of dedicated simulations. The goal here is to try
to identify the simplest models, that is, those with the smallest number of free
parameters, but still have the capacity to provide a reasonable description for clusters
that are evidently beyond the reach of one-component models. With this tool, we aim at
identifying the key factors that characterize mass segregation or the presence of multiple
populations. To reduce the relevant parameter space, we formulate a few physical arguments
based on recent observations and simulations. A first application to two well-studied
globular clusters is briefly described and discussed.
关键词：globular clusters: general;stars: kinematics and dynamics;globular
clusters: individual: NGC 104 (47 Tuc);globular clusters: individual: NGC 5139
(ωCen)
