{
  "id": "2005.02592",
  "version": "v1",
  "published": "2020-05-06T04:51:14.000Z",
  "updated": "2020-05-06T04:51:14.000Z",
  "title": "Doppler imaging and differential rotation of $σ^{2}$ Coronae Borealis using SONG",
  "authors": [
    "Yue Xiang",
    "Shenghong Gu",
    "A. Collier Cameron",
    "J. R. Barnes",
    "J. Christensen-Dalsgaard",
    "F. Grundahl",
    "V. Antoci",
    "M. F. Andersen",
    "P. L. Pallé"
  ],
  "comment": "9 figures, 2 tables, accepted for publication in ApJ",
  "doi": "10.3847/1538-4357/ab8229",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We present new Doppler images of both components of the double-lined binary $\\sigma^{2}$ CrB, based on the high-resolution spectroscopic data collected during 11 nights in 2015 March--April. The observed spectra form two independent data sets with sufficient phase coverage. We apply the least-squares deconvolution to all observed spectra to obtain high signal-to-noise mean profiles, from which we derive the Doppler images of both components of $\\sigma^{2}$ CrB simultaneously. The surfaces of both F9 and G0 components are dominated by pronounced polar spots. The F9 component exhibits a weak spot at latitude 30$^{\\circ}$ and its mid-to-low latitudes are relatively featureless. The G0 star shows an extended spot structure at latitude 30$^{\\circ}$, and its surface spot coverage is larger than that of the F9 star, which suggests a higher level of magnetic activity. With the cross-correlation method, we derive a solar-like surface differential rotation on the G0 star of $\\sigma^{2}$ CrB for the first time, and the surface shear rate is $\\Delta \\Omega = 0.180 \\pm 0.004$ rad d$^{-1}$ and $\\alpha = \\Delta \\Omega / \\Omega_{eq} = 0.032 \\pm 0.001$. We do not obtain a clear surface shear law for the F9 star due to the lack of mid-to-low latitude features, but detect a systematic longitude shift of high-latitude spots, which indicates a slower rotation with respect to the co-rotating frame.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-05-06T04:51:14.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "differential rotation",
      "coronae borealis",
      "doppler imaging",
      "doppler images",
      "clear surface shear law"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}