SCYON Abstract

Received on January 10 2012

Simulations of the Hyades

AuthorsA. Ernst (1), A. Just (1), P. Berczik (1,3,4,5), and C. Olczak (1,2,3,4)
Affiliation(1) Astronomisches Rechen-Institut am Zentrum für Astronomie Heidelberg
(2) Max-Planck-Institut fuer Astronomie Heidelberg
(3) National Astronomical Observatories of China
(4) The Kavli Institute for Astronomy and Astrophysics at Beijing University
(5) Main Astronomical Observatory Kiev
Accepted byAstronomy & Astrophysics
Contactaernst@ari.uni-heidelberg.de
URLhttp://arxiv.org/abs/1110.1274
Links Hyades

Abstract

Context: Using the recent observational data of Röser et al. we present N-body simulations of the Hyades open cluster.
Aims: We make an attempt to determine initial conditions of the Hyades cluster at the time of its formation in order to reproduce the present-day cumulative mass profile, stellar mass and luminosity function (LF).
Methods: We performed direct N-body simulations of the Hyades in an analytic Milky Way potential that account for stellar evolution and include primordial binaries in a few models. Furthermore, we applied a Kroupa (2001) IMF and used extensive ensemble-averaging.
Results: We find that evolved single-star King initial models with King parameters W0 = 6-9 and initial particle numbers N0 = 3000 provide good fits to the observational present-day cumulative mass profile within the Jacobi radius. The best-fit King model has an initial mass of 1721 M(sun) and an average mass loss rate of -2.2 M(sun)/Myr. The K-band LFs of models and observations show a reasonable agreement. Mass segregation is detected in both observations and models. If 33% primordial binaries are included the initial particle number is reduced by 5% as compared to the model without primordial binaries.
Conclusions: The present-day properties of the Hyades can be well reproduced by a standard King or Plummer initial model when choosing appropriate initial conditions. The degeneracy of good-fitting models can be quite high due to the large dimension of the parameter space. More simulations with different Roche-lobe filling factors and primordial binary fractions are required to explore this degeneracy in more detail.