{
  "id": "1209.0766",
  "version": "v1",
  "published": "2012-09-04T20:00:02.000Z",
  "updated": "2012-09-04T20:00:02.000Z",
  "title": "The mass function and dynamical mass of young star clusters: Why their initial crossing-time matters crucially",
  "authors": [
    "Genevieve Parmentier",
    "Holger Baumgardt"
  ],
  "comment": "14 pages, 10 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We highlight the impact of cluster-mass-dependent evolutionary rates upon the evolution of the cluster mass function during violent relaxation, that is, while clusters dynamically respond to the expulsion of their residual star-forming gas. Mass-dependent evolutionary rates arise when the mean volume density of cluster-forming regions is mass-dependent. In that case, even if the initial conditions are such that the cluster mass function at the end of violent relaxation has the same shape as the embedded-cluster mass function (i.e. infant weight-loss is mass-independent), the shape of the cluster mass function does change transiently {\\it during} violent relaxation. In contrast, for cluster-forming regions of constant mean volume density, the cluster mass function shape is preserved all through violent relaxation since all clusters then evolve at the same mass-independent rate. On the scale of individual clusters, we model the evolution of the ratio between the dynamical mass and luminous mass of a cluster after gas expulsion. Specifically, we map the radial dependence of the time-scale for a star cluster to return to equilibrium. We stress that fields-of-view a few pc in size only, typical of compact clusters with rapid evolutionary rates, are likely to reveal cluster regions which have returned to equilibrium even if the cluster experienced a major gas expulsion episode a few Myr earlier. We provide models with the aperture and time expressed in units of the initial half-mass radius and initial crossing-time, respectively, so that our results can be applied to clusters with initial densities, sizes, and apertures different from ours.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-09-04T20:00:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "young star clusters",
      "initial crossing-time matters",
      "dynamical mass",
      "violent relaxation",
      "evolutionary rates"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1111/j.1365-2966.2012.22004.x",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2012,
      "month": "Dec",
      "volume": 427,
      "number": 3,
      "pages": 1940
    },
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1184421,
      "adsabs": "2012MNRAS.427.1940P"
    }
  }
}