{
  "id": "1602.02933",
  "version": "v1",
  "published": "2016-02-09T11:01:58.000Z",
  "updated": "2016-02-09T11:01:58.000Z",
  "title": "Spectroscopic study of Be-shell stars: 4 Her and 88 Her",
  "authors": [
    "Bhat S Shruthi",
    "K T Paul",
    "Subramaniam Annapurni",
    "Mathew Blesson"
  ],
  "comment": "17 pages, 5 figures",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We present the optical spectroscopic study based on 41 spectra of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotational velocity of these stars from He{\\sc i} lines in the blue spectral region (4000--4500 \\AA). We find that these stars are likely to be rotating at a fractional critical rotation of $\\sim$ 0.80. We measure the average $I_p/I_c$ ratio to quantify the strength of the H$\\alpha$ line and obtain 1.63 for 4 Her and 2.06 for 88 Her. The radius of the H$\\alpha$ emission region is estimated to be $R_d/R_*$ $\\sim$ 5.0, assuming a Keplerian disk. These stars are thus found to be fast rotators with relatively small H$\\alpha$ emission region. We detect V/R variation of H$\\alpha$ spectral line during the observed period. We re-estimate the periods for both the stars and obtain two periods of $\\sim$ 46 days and its harmonic of 23.095 days for 4 Her and $\\sim$ 86 days for 88 Her. As these two are shell stars with binaries and have low H$\\alpha$ EW with the emission region closer to the central star, the V/R variation and a change in period may be an effect of the binary on the circumstellar disk.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-02-09T11:01:58.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spectroscopic study",
      "be-shell stars",
      "blue spectral region",
      "emission region closer",
      "detect v/r variation"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}