{
  "id": "astro-ph/9709027",
  "version": "v1",
  "published": "1997-09-03T18:18:56.000Z",
  "updated": "1997-09-03T18:18:56.000Z",
  "title": "ORFEUS-I Observations of Molecular Hydrogen in the Galactic Disk",
  "authors": [
    "W. Van Dyke Dixon",
    "Mark Hurwitz",
    "Stuart Bowyer"
  ],
  "comment": "LaTeX file, 19 pages, 6 encapsulated PostScript figures. Uses aaspp4.sty and astrobib.sty. (Astrobib is available from http://www.stsci.edu/software/TeX.html .) To be published in The Astrophysical Journal, Vol. 492, January 1998",
  "journal": "Astrophys.J. 492 (1998) 569",
  "doi": "10.1007/BFb0104730",
  "categories": [
    "astro-ph"
  ],
  "abstract": "We present measurements of interstellar H_2 absorption lines in the continuum spectra of seven early-type stars in the Galactic disk at distances between 1 and 4 kpc. Five of these stars provide lines of sight through the Sagittarius spiral arm. The spectra, obtained with the Berkeley EUV/FUV spectrometer on the ORFEUS telescope in 1993 September, have a resolution of 3000 and statistical signal-to-noise ratios between 20 and 80. We determine column densities for each observed rotational level and derive excitation temperatures and densities for the H_2 clouds along each line of sight. Our data continue the relationships among H_2 column density, fractional molecular abundance, and reddening apparent in Copernicus observations of nearby stars, indicating a common mechanism for H_2 production. Estimates of cloud temperatures and densities are consistent with those derived from Copernicus data. We find that the molecular fraction of hydrogen is nearly constant over a wide range of distances and mean reddenings, consistent with a model in which a significant fraction of the neutral ISM is associated with H_2-bearing molecular clouds, even along low-density lines of sight.",
  "revisions": [
    {
      "version": "v1",
      "updated": "1997-09-03T18:18:56.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic disk",
      "molecular hydrogen",
      "orfeus-i observations",
      "column density",
      "berkeley euv/fuv spectrometer"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "LaTeX",
      "pages": 19,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 462041
    }
  }
}