{
  "id": "2112.14742",
  "version": "v2",
  "published": "2021-12-29T18:50:23.000Z",
  "updated": "2022-05-19T17:06:46.000Z",
  "title": "New Fe I Level Energies and Line Identifications from Stellar Spectra. III. Initial Results from UV, Optical, and Infrared Spectra",
  "authors": [
    "Ruth C. Peterson",
    "Robert L. Kurucz"
  ],
  "comment": "23 pages, 1 figure. Near-final ApJS version. Section 9 characterizes and quantifies uncertainties in deduced level energies and astrophysical dgf values. Table 3 includes >16,000 Fe I lines potentially detectable in solar-metallicity dwarfs and giants, and dgf values for >2,000 of these. It is currently available from the website of R. Kurucz at http://kurucz.harvard.edu/atoms/2600/PK21/table3.txt",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "The spectrum of neutral iron is critical to astrophysics, yet furnace laboratory experiments cannot reach many high-lying Fe I levels. Instead, Peterson & Kurucz (2015) and Peterson, Kurucz & Ayres (2017) turned to UV and optical spectra of warm stars to identify and assign energies for 124 Fe I levels with 1900 detectable Fe I lines, and to derive astrophysical gf values for over a thousand of these. An energy value was assumed for each unknown Fe I level, and confirmed if it shifted the predicted positions in updated Kurucz (2011) Fe I calculations to match exactly in wavelength the positions of four or more unidentified lines in the observed spectra. Nearly all these identifications were for LS levels characterized by spin-orbit coupling, whose lines fall primarily at UV and optical wavelengths. This extension of these searches provides nearly a hundred new Fe I level identifications. Thirty-nine LS levels are identified largely by incorporating published positions of unidentified laboratory Fe I lines with wavelengths < 2000A. Adding infrared spectra provided sixty Fe I jK levels, where a single isolated outer electron orbits a compact core. Their weak, blended lines fall mostly in the infrared, but are searchable because their mutual energies obey tight relationships. For each new Fe I level, this work again provides and makes publicly available its identification, its energy, and a list of over 16,000 of its potentially detectable lines with theoretical gf values. For over 2,000 of these, this work also includes astrophysical gf values, ones adjusted semi-empirically to fit the stellar spectra. The potential impact of this work on modeling UV and IR stellar spectra is noted.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2022-05-19T17:06:46.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "stellar spectra",
      "infrared spectra",
      "initial results",
      "level energies",
      "line identifications"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 23,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}