{
  "id": "1401.4979",
  "version": "v1",
  "published": "2014-01-20T16:44:04.000Z",
  "updated": "2014-01-20T16:44:04.000Z",
  "title": "The Gaia-ESO Survey: Kinematic structure in the Gamma Velorum Cluster",
  "authors": [
    "R. D. Jeffries",
    "R. J. Jackson",
    "M. Cottaar",
    "S. E. Koposov",
    "A. C. Lanzafame",
    "M. R. Meyer",
    "L. Prisinzano",
    "S. Randich",
    "G. G. Sacco",
    "E. Brugaletta",
    "M. Caramazza",
    "F. Damiani",
    "E. Franciosini",
    "A. Frasca",
    "G. Gilmore",
    "S. Feltzing",
    "G. Micela",
    "E. Alfaro",
    "T. Bensby",
    "E. Pancino",
    "A. Recio-Blanco",
    "P. de Laverny",
    "J. Lewis",
    "L. Magrini",
    "L. Morbidelli",
    "M. T. Costado",
    "P. Jofre",
    "A. Klutsch",
    "K. Lind",
    "E. Maiorca"
  ],
  "comment": "Accepted for publication in Astronomy & Astrophysics (15 pages)",
  "doi": "10.1051/0004-6361/201323288",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "Context: A key science goal of the Gaia-ESO survey (GES) is to use the kinematics of low-mass stars in young clusters to probe their dynamical histories and how they populate the field as they become unbound. The clustering of low-mass stars around the massive W-R binary gamma^2 Velorum was one of the first GES targets. Aims: To empirically determine the radial velocity (RV) precision of GES data, construct a kinematically unbiased sample of cluster members and characterise their dynamical state. Methods: Targets were selected from colour-magnitude diagrams and intermediate resolution spectroscopy used to derive RVs and assess membership from the strength of the Li6708A line. The RV distribution was analysed using a maximum likelihood technique that accounts for unresolved binaries. Results: The GES RV precision is about 0.25km/s and sufficient to resolve velocity structure in the low-mass population around gamma^2 Vel. The structure is well fitted by two kinematic components with roughly equal numbers of stars; the first has an intrinsic dispersion of 0.34+/-0.16km/s, consistent with virial equilibrium. The second has a broader dispersion of 1.60+/-0.37km/s and is offset from the first by ~2km/s. The first population is older by 1-2Myr based on a greater level of Li depletion seen among its M-stars and is probably more centrally concentrated around gamma^2 Vel. Conclusions: We consider several formation scenarios, concluding that the two kinematic components are a bound remnant of the original, denser cluster that formed gamma^2 Vel, and a dispersed population from the wider Vela OB2 association, of which gamma^2 Vel is the most massive member. The apparent youth of gamma^2 Vel compared to the older (>=10Myr) low-mass population surrounding it suggests a scenario where the massive binary formed in a clustered environment after the formation of the bulk of the low-mass stars.[abridged]",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-01-20T16:44:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gamma velorum cluster",
      "gaia-eso survey",
      "kinematic structure",
      "low-mass stars",
      "kinematic components"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "Astronomy and Astrophysics",
      "year": 2014,
      "month": "Mar",
      "volume": 563
    },
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2014A&A...563A..94J"
    }
  }
}