Phase models of the Milky Way stellar disc

ABSTRACT We present a new iterative method for constructing equilibrium phase models of stellar systems. Importantly, this method can provide phase models with arbitrary mass distributions. The method is based on the following principle. Our task is to generate an equilibrium N ‐body system with a given mass distribution. For this purpose, we let the system reach equilibrium through its dynamical evolution. During this evolution we hold mass distribution in this system. This principle is realized in our method by means of an iterative procedure. We have used our method to construct a phase model of the disc of our Galaxy. In our method, we use the mass distribution in the Galaxy as input data. Here we used two Galactic density models (suggested by Flynn, Sommer‐Larsen and Christensen and by Dehnen and Binney). For a fixed‐mass model of the Galaxy we can construct a one‐parameter family of equilibrium models of the Galactic disc. We can, however, choose a unique model using local kinematic parameters that are known from Hipparcos data. We show that the phase models constructed using our method are close to equilibrium. The problem of uniqueness for our models is discussed, and we discuss some further applications of our method.