{
  "id": "1207.2165",
  "version": "v1",
  "published": "2012-07-09T20:17:23.000Z",
  "updated": "2012-07-09T20:17:23.000Z",
  "title": "Coronal Structure of Low-Mass Stars",
  "authors": [
    "Pauline Lang",
    "Moira Jardine",
    "Jean-Francois Donati",
    "Julien Morin",
    "Aline Vidotto"
  ],
  "comment": "12 pages, 10 figures, Published in MNRAS",
  "doi": "10.1111/j.1365-2966.2012.21288.x",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We investigate the change in stellar magnetic topology across the fully-convective boundary and its effects on coronal properties. We consider both the magnitude of the open flux that influences angular momentum loss in the stellar wind and X-ray emission measure. We use reconstructed maps of the radial magnetic field at the stellar surface and the potential-field source surface method to extrapolate a 3D coronal magnetic field for a sample of early-to-mid M dwarfs. During the magnetic reconstruction process it is possible to force a solution towards field geometries that are symmetric or antisymmetric about the equator but we demonstrate that this has only a modest impact on the coronal tracers mentioned above. We find that the dipole component of the field, which governs the large-scale structure, becomes increasingly strong as the stellar mass decreases, while the magnitude of the open (wind-bearing) magnetic flux is proportional to the magnitude of the reconstructed magnetic flux. By assuming a hydrostatic and isothermal corona we calculate X-ray emission measures (in magnitude and rotational modulation) for each star and, using observed stellar densities as a constraint, we reproduce the observed X-ray saturation at Ro < 0.1. We find that X-ray rotational modulation is not a good indicator of magnetic structure as it shows no trend with Rossby number but can be useful in discriminating between different assumptions on the field geometry.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-07-09T20:17:23.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "coronal structure",
      "low-mass stars",
      "x-ray emission measure",
      "magnetic flux",
      "3d coronal magnetic field"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "Wiley-Blackwell",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2012,
      "month": "Aug",
      "volume": 424,
      "number": 2,
      "pages": 1077
    },
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1121827,
      "adsabs": "2012MNRAS.424.1077L"
    }
  }
}