{
  "id": "1007.0002",
  "version": "v1",
  "published": "2010-06-30T20:00:03.000Z",
  "updated": "2010-06-30T20:00:03.000Z",
  "title": "Deep infrared imaging of close companions to austral A- and F-type stars",
  "authors": [
    "David Ehrenreich",
    "Anne-Marie Lagrange",
    "Guillaume Montagnier",
    "Gaël Chauvin",
    "Franck Galland",
    "Jean-Luc Beuzit",
    "Julien Rameau"
  ],
  "comment": "21 pages, 12 figures, 7 tables. Accepted for publication in Astronomy and Astrophysics. The full version of the preprint including the appendices (24 pages of figures), can be retrieved at http://www-laog.obs.ujf-grenoble.fr/~dehrenre/articles/afsurvey/",
  "categories": [
    "astro-ph.SR",
    "astro-ph.EP"
  ],
  "abstract": "The search for substellar companions around stars with different masses along the main sequence is critical to understand the different processes leading to the formation of low-mass stars, brown dwarfs, and planets. In particular, the existence of a large population of low-mass stars and brown dwarfs physically bound to early-type main-sequence stars could imply that the massive planets recently imaged at wide separations (10-100 AU) around A-type stars are disc-born objects in the low-mass tail of the binary distribution. Our aim is to characterize the environment of early-type main-sequence stars by detecting brown dwarf or low-mass star companions between 10 and 500 AU. High contrast and high angular resolution near-infrared images of a sample of 38 southern A- and F-type stars have been obtained between 2005 and 2009 with the instruments VLT/NaCo and CFHT/PUEO. Multi-epoch observations were performed to discriminate comoving companions from background contaminants. About 41 companion candidates were imaged around 23 stars. Follow-up observations for 83% of these stars allowed us to identify a large number of background contaminants. We report the detection of 7 low-mass stars with masses between 0.1 and 0.8 Msun in 6 multiple systems: the discovery of a M2 companion around the A5V star HD14943 and the detection of the B component of the F4V star HD41742 quadruple system; we resolve the known companion of the F6.5V star HD49095 as a short-period binary system composed by 2 M/L dwarfs. We also resolve the companions to the astrometric binaries iot Crt (F6.5V) and 26 Oph (F3V), and identify a M3/M4 companion to the F4V star omi Gru, associated with a X-ray source. The global multiplicity fraction measured in our sample of A and F stars is >16%. A parallel velocimetric survey of our stars let us conclude that the imaged companions can impact on the observed radial velocity measurements.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-06-30T20:00:03.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "f-type stars",
      "deep infrared imaging",
      "low-mass star",
      "close companions",
      "angular resolution near-infrared images"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1051/0004-6361/201014763",
      "journal": "Astronomy and Astrophysics",
      "year": 2010,
      "month": "Nov",
      "volume": 523
    },
    "note": {
      "typesetting": "TeX",
      "pages": 21,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 860078,
      "adsabs": "2010A&A...523A..73E"
    }
  }
}