{
  "id": "1506.02980",
  "version": "v1",
  "published": "2015-06-09T16:15:28.000Z",
  "updated": "2015-06-09T16:15:28.000Z",
  "title": "Dynamical masses of a nova-like variable on the edge of the period gap",
  "authors": [
    "P. Rodríguez-Gil",
    "T. Shahbaz",
    "T. R. Marsh",
    "B. T. Gänsicke",
    "D. Steeghs",
    "K. S. Long",
    "I. G. Martínez-Pais",
    "M. Armas Padilla",
    "R. Schwarz",
    "M. R. Schreiber",
    "M. A. P. Torres",
    "D. Koester",
    "V. S. Dhillon",
    "J. Castellano",
    "D. Rodríguez"
  ],
  "comment": "14 pages, 10 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We present the first dynamical determination of the binary parameters of an eclipsing SW Sextantis star in the 3-4 hour orbital period range during a low state. We obtained time-resolved optical spectroscopy and photometry of HS 0220+0603 during its 2004-2005 low brightness state, as revealed in the combined SMARTS, IAC80 and M1 Group long-term optical light curve. The optical spectra taken during primary eclipse reveal a secondary star spectral type of M5.5 $\\pm$ 0.5 as derived from molecular band-head indices. The spectra also provide the first detection of a DAB white dwarf in a cataclysmic variable. By modelling its optical spectrum we estimate a white dwarf temperature of 30000 $\\pm$ 5000 K. By combining the results of modelling the white dwarf eclipse from ULTRACAM light curves with those obtained by simultaneously fitting the emission- and absorption-line radial velocity curves and I-band ellipsoidal light curves, we measure the stellar masses to be M$_1 = 0.87 \\pm 0.09$ M$_\\odot$ and M$_2 = 0.47 \\pm 0.05$ M$_\\odot$ for the white dwarf and the M dwarf, respectively, and an inclination of the orbital plane of $i \\approx 79^\\mathrm{o}$. A radius of $0.0103 \\pm 0.0007$ R$_\\odot$ is obtained for the white dwarf. The secondary star in HS 0220+0603 is likely too cool and undersized for its mass.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-06-09T16:15:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "white dwarf",
      "period gap",
      "dynamical masses",
      "nova-like variable",
      "hour orbital period range"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}