{
  "id": "2205.04475",
  "version": "v1",
  "published": "2022-05-09T18:00:00.000Z",
  "updated": "2022-05-09T18:00:00.000Z",
  "title": "A tentative 114-minute orbital period challenges the ultra-compact nature of the X-ray binary 4U 1812-12",
  "authors": [
    "M. Armas Padilla",
    "P. Rodríguez-Gil",
    "T. Muñoz-Darias",
    "M. A. P. Torres",
    "J. Casares",
    "N. Degenaar",
    "V. S. Dhillon",
    "C. O. Heinke",
    "S. P. Littlefair",
    "T. R. Marsh"
  ],
  "comment": "Accepted for publication in ApJ Letters",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We present a detailed time-resolved photometric study of the ultra-compact X-ray binary candidate 4U 1812-12. The multicolor light curves obtained with HiPERCAM on the 10.4-m Gran Telescopio Canarias show an aprox 114 min modulation similar to a superhump. Under this interpretation, this period should lie very close to the orbital period of the system. Contrary to what its other observational properties suggest (namely, persistent dim luminosity, low optical-to-X-ray flux ratio and lack of hydrogen features in the optical spectrum), this implies that 4U1812-12 is most likely not an ultra-compact X-ray binary, which are usually defined as systems with orbital periods lower than 80 min. We discuss the nature of the system, showing that a scenario in which 4U 1812-12 is the progenitor of an ultra-compact X-ray binary may reconcile all the observables.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-05-09T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray binary 4u",
      "orbital period challenges",
      "ultra-compact nature",
      "ultra-compact x-ray binary candidate 4u",
      "low optical-to-x-ray flux ratio"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}