{
  "id": "astro-ph/0510400",
  "version": "v1",
  "published": "2005-10-13T17:40:28.000Z",
  "updated": "2005-10-13T17:40:28.000Z",
  "title": "Multiwavelength monitoring of BD+53 2790, the optical counterpart to 4U~2206+54",
  "authors": [
    "P. Blay",
    "I. Negueruela",
    "P. Reig",
    "M. J. Coe",
    "R. H. D. Corbet",
    "J. Fabregat",
    "A. E. Tarasov"
  ],
  "comment": "17 pages, 12 figures, 6 Tables",
  "doi": "10.1051/0004-6361:20053951",
  "categories": [
    "astro-ph"
  ],
  "abstract": "We present the results of our long-term monitoring of BD+53 2790, the optical counterpart to the X-ray source 4U~2206+54. Unlike previous studies that classify the source as a Be/X-ray binary, we find that its optical and infrared properties differ from those of typical Be stars: the variability of the V/R ratio is not cyclical; there are variations in the shape and strength of the H$\\alpha$ emission line on timescales less than 1 day; and no correlation between the EW and the IR magnitudes or colors is seen. Our observations suggest that BD+53 2790 is very likely a peculiar O9.5V star. In spite of exhaustive searches we cannot find any significant modulation in any emission line parameter or optical/infrared magnitudes. Spectroscopy of the source extending from the optical to the K-band confirms the peculiarity of the spectrum: not only are the He lines stronger than expected for an O9.5V star but also there is no clear pattern of variability. The possibility that BD+53 2790 is an early-type analogue to He-strong stars (like theta^1 Ori C) is discussed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2005-10-13T17:40:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "optical counterpart",
      "multiwavelength monitoring",
      "5v star",
      "emission line parameter",
      "be/x-ray binary"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 695042
    }
  }
}