{
  "id": "2101.00899",
  "version": "v1",
  "published": "2021-01-04T11:43:44.000Z",
  "updated": "2021-01-04T11:43:44.000Z",
  "title": "Magnetic field geometry and magnetospheric environment of the strongly magnetic Of?p star NGC 1624-2",
  "authors": [
    "S. P. Järvinen",
    "S. Hubrig",
    "M. Schöller",
    "M. Küker",
    "I. Ilyin",
    "S. D. Chojnowski"
  ],
  "comment": "Accepted to be published in MNRAS",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "NGC 1624-2 is an O7f?p star with a reported probable polar magnetic field strength $\\ge$ 20 kG, which is the strongest magnetic field ever measured in an O-type star. We study the variability of the mean longitudinal magnetic field $\\langle B_z \\rangle$ and the mean field modulus $\\langle B \\rangle$ to obtain constraints on its field geometry. Only one magnetic pole is observable over the rotation cycle. The approximately sinusoidal variation of $\\langle B_z \\rangle$ and the ratio of the values of the extrema of $\\langle B \\rangle$ indicate that there is an important component of the field that is dipolar. The $\\langle B_z \\rangle$ values measured over the rotation cycle are in the range from $-0.2$ to 4.5 kG, whereas the values for $\\langle B \\rangle$ vary between 9 and 12 kG. The $\\langle B_z \\rangle$ values obtained using the O III $\\lambda$7455 emission line are in the range from 0.4 to 2.3 kG and show a variability pattern similar to that detected for the absorption lines. The fact that the phase of the $\\langle B_z \\rangle$ minimum coincides with the phase of the $\\langle B \\rangle$ maximum, indicates that the field structure must significantly depart from a centred dipole. Further, we discuss the nature of the observed variable Stokes $V$ profiles corresponding to a longitudinal field of negative polarity detected in the emission He I lines and present the first MHD numerical simulations of the gas flow in the magnetosphere of this star.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-01-04T11:43:44.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "magnetic field geometry",
      "star ngc",
      "magnetospheric environment",
      "strongly magnetic",
      "probable polar magnetic field strength"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}