{
  "id": "1004.4920",
  "version": "v1",
  "published": "2010-04-27T22:44:42.000Z",
  "updated": "2010-04-27T22:44:42.000Z",
  "title": "Bootstrapping the Coronal Magnetic Field with STEREO: I. Unipolar Potential Field Modeling",
  "authors": [
    "Markus J. Aschwanden",
    "Anne W. Sandman"
  ],
  "comment": "12 figures, manuscript submitted to ApJ, 2010 Apr 27",
  "journal": "Astronomical Journal Vol. 140, p. 723-734, (2010)",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We investigate the recently quantified misalignment of $\\alpha_{mis} \\approx 20^\\circ-40^\\circ$ between the 3-D geometry of stereoscopically triangulated coronal loops observed with STEREO/EUVI (in four active regions) and theoretical (potential or nonlinear force-free) magnetic field models extrapolated from photospheric magnetograms. We develop an efficient method of bootstrapping the coronal magnetic field by forward-fitting a parameterized potential field model to the STEREO-observed loops. The potential field model consists of a number of unipolar magnetic charges that are parameterized by decomposing a photospheric magnetogram from MDI. The forward-fitting method yields a best-fit magnetic field model with a reduced misalignment of $\\alpha_{PF} \\approx 13^\\circ-20^\\circ$. We evaluate also stereoscopic measurement errors and find a contribution of $\\alpha_{SE}\\approx 7^\\circ-12^\\circ$, which constrains the residual misalignment to $\\alpha_{NP}=\\alpha_{PF}-\\alpha_{SE}\\approx 5^\\circ -9^\\circ$, which is likely due to the nonpotentiality of the active regions. The residual misalignment angle $\\alpha_{NP}$ of the potential field due to nonpotentiality is found to correlate with the soft X-ray flux of the active region, which implies a relationship between electric currents and plasma heating.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2010-04-27T22:44:42.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "coronal magnetic field",
      "unipolar potential field modeling",
      "active region",
      "residual misalignment",
      "potential field model consists"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-6256/140/3/723",
      "journal": "The Astronomical Journal",
      "year": 2010,
      "month": "Sep",
      "volume": 140,
      "number": 3,
      "pages": 723
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 853317,
      "adsabs": "2010AJ....140..723A"
    }
  }
}