Do open star clusters evolve towards energy equipartition?

Article, Preprint English OPEN
Spera, M ; Mapelli, M ; Jeffries, RD (2016)
  • Publisher: Oxford University Press
  • Related identifiers: doi: 10.1093/mnras/stw998
  • Subject: Astrophysics - Solar and Stellar Astrophysics | QB | QC | Astrophysics - Astrophysics of Galaxies
    arxiv: Astrophysics::Galaxy Astrophysics | Astrophysics::Cosmology and Extragalactic Astrophysics | Astrophysics::Earth and Planetary Astrophysics | Astrophysics::Solar and Stellar Astrophysics

We investigate whether open clusters (OCs) tend to energy equipartition, by means of direct N-body simulations with a broken power-law mass function. We find that the simulated OCs become strongly mass segregated, but the local velocity dispersion does not depend on the stellar mass for most of the mass range: the curve of the velocity dispersion as a function of mass is nearly flat even after several half-mass relaxation times, regardless of the adopted stellar evolution recipes and Galactic tidal field model. This result holds both if we start from virialized King models and if we use clumpy sub-virial initial conditions. The velocity dispersion of the most massive stars and stellar remnants tends to be higher than the velocity dispersion of the lighter stars. This trend is particularly evident in simulations without stellar evolution. We interpret this result as a consequence of the strong mass segregation, which leads to Spitzer's instability. Stellar winds delay the onset of the instability. Our simulations strongly support the result that OCs do not attain equipartition, for a wide range of initial conditions.
  • References (82)
    82 references, page 1 of 9

    Alessandrini E., Lanzoni B., Miocchi P., Ciotti L., Ferraro F. R., 2014, ApJ, 795, 169

    Allen C., Santillan A., 1991, Rev. Mex. Astron. Astrofis., 22, 255

    Allison R. J., Goodwin S. P., Parker R. J., Portegies Zwart S. F., de Grijs R., Kouwenhoven M. B. N., 2009, MNRAS, 395, 1449

    Anderson J., van der Marel R. P., 2010, ApJ, 710, 1032

    Arca-Sedda M., 2016, MNRAS, 455, 35

    Beccari G., Dalessandro E., Lanzoni B., Ferraro F. R., Bellazzini M., Sollima A., 2015, ApJ, 814, 144

    Berghea C. T., Dudik R. P., Tincher J., Winter L. M., 2013, ApJ, 776, 100

    Bianchini P., van de Ven G., Norris M. A., Schinnerer E., Varri A. L., 2016, MNRAS, 458, 3644

    Binney J., Tremaine S., 2008, Galactic Dynamics, 2nd edn. Princeton Univ. Press, Princeton, NJ

    Boltzmann L., 1876, Wiener Ber, 74, 553

  • Similar Research Results (1)
  • Metrics
    No metrics available
Share - Bookmark