{
  "id": "2201.01792",
  "version": "v1",
  "published": "2022-01-05T19:13:00.000Z",
  "updated": "2022-01-05T19:13:00.000Z",
  "title": "Redshifted methanol absorption tracing infall motions of high-mass star formation regions",
  "authors": [
    "W. J. Yang",
    "K. M. Menten",
    "A. Y. Yang",
    "F. Wyrowski",
    "Y. Gong",
    "S. P. Ellingsen",
    "C. Henkel",
    "X. Chen",
    "Y. Xu"
  ],
  "comment": "21 pages, 13 figures, 5 tables. Accepted for publication in A&A",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "Gravitational collapse is one of the most important processes in high-mass star formation. Compared with the classic blue-skewed profiles, redshifted absorption against continuum emission is a more reliable method to detect inward motions within high-mass star formation regions. We aim to test if methanol transitions can be used to trace infall motions within high-mass star formation regions. Using the Effelsberg-100 m, IRAM-30 m, and APEX-12 m telescopes, we carried out observations of 37 and 16 methanol transitions towards two well-known collapsing dense clumps, W31C (G10.6-0.4) and W3(OH), to search for redshifted absorption features or inverse P-Cygni profiles. Redshifted absorption is observed in 14 and 11 methanol transitions towards W31C and W3(OH), respectively. The infall velocities fitted from a simple two-layer model agree with previously reported values derived from other tracers, suggesting that redshifted methanol absorption is a reliable tracer of infall motions within high-mass star formation regions. Our observations indicate the presence of large-scale inward motions, and the mass infall rates are roughly estimated to be $\\gtrsim$10$^{-3}$ $M_{\\odot}$yr$^{-1}$, which supports the global hierarchical collapse and clump-fed scenario. With the aid of bright continuum sources and the overcooling of methanol transitions leading to enhanced absorption, redshifted methanol absorption can trace infall motions within high-mass star formation regions hosting bright H{\\scriptsize II} regions.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-01-05T19:13:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high-mass star formation regions",
      "methanol absorption tracing infall motions",
      "redshifted methanol absorption tracing infall"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 21,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}