{
  "id": "2006.00950",
  "version": "v1",
  "published": "2020-06-01T13:58:16.000Z",
  "updated": "2020-06-01T13:58:16.000Z",
  "title": "TESS photometry of helium-rich hot subdwarfs: r modes in BD+37 442 and BD+37 1977",
  "authors": [
    "C. Simon Jeffery"
  ],
  "comment": "MNRAS accepted, 6 pages, 3 figures",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "TESS photometry of the extremely helium-rich hot subdwarfs BD+37 442 and BD+37 1977 demonstrates multi-periodic low-amplitude variability with principal periods of 0.56 and 1.14 d, respectively, and with both first and second harmonics present. The lightcurves are not perfectly regular, implying additional periodic and/or non-periodic content. Possible causes are examined, including the binary hypothesis originally introduced to explain X-ray observations, differentially rotating surface inhomogeneities, and pulsations. If the principal photometric periods correspond to the rotation periods, the stars are rotating at approximately 0.7 and 0.3 x breakup, respectively. Surface Rossby waves (r modes) therefore provide the most likely solution.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-06-01T13:58:16.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "tess photometry",
      "principal photometric periods correspond",
      "demonstrates multi-periodic low-amplitude variability",
      "explain x-ray observations",
      "extremely helium-rich hot subdwarfs"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}