{
  "id": "1707.09017",
  "version": "v1",
  "published": "2017-07-27T19:39:02.000Z",
  "updated": "2017-07-27T19:39:02.000Z",
  "title": "Magnetic field geometry and chemical abundance distribution of the He-strong star CPD -57 3509",
  "authors": [
    "S. Hubrig",
    "N. Przybilla",
    "H. Korhonen",
    "I. Ilyin",
    "M. Schöller",
    "S. P. Jarvinen",
    "M. -F. Nieva",
    "R. -D. Scholz",
    "S. Kimeswenger",
    "M. Ramolla",
    "A. F. Kholtygin",
    "M. Briquet"
  ],
  "comment": "11 pages, 5 tables, 7 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "The magnetic field of CPD -57 3509 was recently detected in the framework of the BOB (B fields in OB stars) collaboration. We acquired low-resolution spectropolarimetric observations of CPD -57 3509 with FORS2 and high-resolution UVES observations randomly distributed over a few months to search for periodicity, to study the magnetic field geometry, and to determine the surface distribution of silicon and helium. We also obtained supplementary photometric observations at a timeline similar to the spectroscopic and spectropolarimetric observations. A period of 6.36d was detected in the measurements of the mean longitudinal magnetic field. A sinusoidal fit to our measurements allowed us to constrain the magnetic field geometry and estimate the dipole strength in the range of 3.9-4.5kG. Our application of the Doppler imaging technique revealed the presence of He I spots located around the magnetic poles, with a strong concentration at the positive pole and a weaker one around the negative pole. In contrast, high concentration Si III spots are located close to the magnetic equator. Further, our analysis of the spectral variability of CPD -57 3509 on short time scales indicates distinct changes in shape and position of line profiles possibly caused by the presence of beta Cep-like pulsations. A small periodic variability in line with the changes of the magnetic field strength is clearly seen in the photometric data.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-07-27T19:39:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "magnetic field geometry",
      "he-strong star cpd",
      "chemical abundance distribution",
      "mean longitudinal magnetic field",
      "spectropolarimetric observations"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}