{
  "id": "1208.2153",
  "version": "v2",
  "published": "2012-08-10T12:09:15.000Z",
  "updated": "2012-10-02T09:01:26.000Z",
  "title": "Helium Emissions Observed in Ground-Based Spectra of Solar Prominences",
  "authors": [
    "Renzo Ramelli",
    "Goetz Stellmacher",
    "Eberhard Wiehr",
    "Michele Bianda"
  ],
  "comment": "12 pages, 5 figure, 3 tables",
  "doi": "10.1007/s11207-012-0118-2",
  "categories": [
    "astro-ph.SR",
    "physics.plasm-ph"
  ],
  "abstract": "The only prominent line of singly ionized helium in the visible spectral range, helium-II 4686 A, is observed together with the helium-I 5015 A singlet and the helium-I 4471 A triplet line in solar prominences. The sodium emission, NaD2, is used as a tracer for helium-II emissions which are sufficiently bright to exceed the noise level near 10^-6 of the disk-center intensity. The so selected prominences are characterized by small non-thermal line broadening and almost absent velocity shifts, yielding narrow line profiles without wiggles. The reduced widths [Delta(lambda_D) / lambda] of helium-II 4686 A are 1.5 times broader than those of helium-I 4471 A triplet and 1.65 times broader than those of helium-I 5015 A singlet. This indicates that the helium lines originate in a prominence--corona transition region with outwards increasing temperature.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2012-10-02T09:01:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "solar prominences",
      "helium emissions",
      "ground-based spectra",
      "times broader",
      "helium lines originate"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "Solar Physics",
      "year": 2012,
      "month": "Dec",
      "volume": 281,
      "number": 2,
      "pages": 697
    },
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1127222,
      "adsabs": "2012SoPh..281..697R"
    }
  }
}