{
  "id": "astro-ph/0110279",
  "version": "v1",
  "published": "2001-10-11T20:05:13.000Z",
  "updated": "2001-10-11T20:05:13.000Z",
  "title": "Molecular Hydrogen in High-Velocity Clouds",
  "authors": [
    "Philipp Richter",
    "Kenneth R. Sembach",
    "Bart P. Wakker",
    "Blair D. Savage"
  ],
  "comment": "12 pages, 3 figures; Accepted for publication in ApJ Letters",
  "doi": "10.1086/338050",
  "categories": [
    "astro-ph"
  ],
  "abstract": "We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar molecular hydrogen (H_2) in two Galactic high-velocity clouds (HVCs). Molecular hydrogen absorption is detected in the Magellanic Stream (abundance ~0.3 solar) toward the Seyfert galaxy Fairall 9 in the lowest three rotational states (J=0-2) at v(LSR)=+190 km/s, yielding a total H_2 column density of log N(H_2)=16.40(+0.26)(-0.53). In contrast, no H_2 absorption is seen in the high-velocity cloud Complex C (abundance ~0.1 solar) toward the quasar PG 1259+593 (log N(H_2)<13.96 at v(LSR)=-130 km/s) although both HVCs have similar HI column densities on the order of log N(HI)~20. Weak H_2 absorption is detected in the Intermediate-Velocity Arch (IV Arch; abundance \\~1.0 solar) toward PG 1259+593 (log N(H_2)=14.10(+0.21)(-0.44) at v(LSR)=-55 km/s and log N(HI)=19.5). It thus appears that metal- and dust-poor halo clouds like Complex C are not able to form and maintain widely distributed H_2, whereas metal and dust-rich halo clouds like the IV Arch can maintain H_2 even at low HI column densities.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2001-10-11T20:05:13.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "column density",
      "low hi column densities",
      "far ultraviolet spectroscopic explorer",
      "similar hi column densities",
      "high-velocity cloud complex"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 577333
    }
  }
}