{
  "id": "1804.04709",
  "version": "v1",
  "published": "2018-04-12T20:01:26.000Z",
  "updated": "2018-04-12T20:01:26.000Z",
  "title": "Rotation of the asymptotic giant branch star R Doradus",
  "authors": [
    "W. H. T. Vlemmings",
    "T. Khouri",
    "E. De Beck",
    "H. Olofsson",
    "G. Garcia-Segura",
    "E. Villaver",
    "A. Baudry",
    "E. M. L. Humphreys",
    "M. Maercker",
    "S. Ramstedt"
  ],
  "comment": "12 pages, 15 figures, Accepted for publication in Astronomy & Astrophysics",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "High resolution observations of the extended atmospheres of asymptotic giant branch (AGB) stars can now directly confront the theories that describe stellar mass loss. Using Atacama Large Millimeter/submillimeter Array (ALMA) high angular resolution ($30\\times42$~mas) observations we have, for the first time, resolved stellar rotation of an AGB star, R~Dor. We measure an angular rotation velocity of $\\omega_R\\sin{i}=(3.5\\pm0.3)\\times10^{-9}$~rad~s$^{-1}$ which indicates a rotational velocity of $|\\upsilon_{\\rm rot}\\sin{i}|=1.0\\pm0.1$~km~s$^{-1}$ at the stellar surface ($R_*=31.2$~mas at $214$~GHz). The rotation axis projected on the plane of the sky has a position angle $\\Phi=7\\pm6^\\circ$. We find that the rotation of R Dor is two orders of magnitude faster than expected for a solitary AGB star that will have lost most of its angular momentum. Its rotational velocity is consistent with angular momentum transfer from a close companion. As a companion has not been directly detected we thus suggest R~Dor has a low-mass, close-in, companion. The rotational velocity approaches the critical velocity, set by the local sound speed in the extended envelope, and is thus expected to affect the mass loss characteristics of R~Dor.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-04-12T20:01:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "asymptotic giant branch star",
      "rotational velocity",
      "agb star",
      "angular momentum",
      "atacama large millimeter/submillimeter array"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}