Comparing the CO and HI distributions in nearby spiral galaxies at high resolution

Tony Wong, Leo Blitz, J. M. Van Der Hulst

Research output: Contribution to journalArticlepeer-review


With wide-field CO maps of spiral galaxies at ∼ 6″ resolution provided by the BIMA Survey of Nearby Galaxies (BIMA SONG), it is now feasible to compare the CO and HI distributions in disks on scales of ∼1 kpc or less. The results of such a comparison suggest that, when azimuthally averaged, the ratio of CO to HI emission, and by implication the molecular-to-atomic gas ratio, is determined by the midplane interstellar pressure, with the ISM metallicity as a secondary factor. A variety of observed phenomena, including the inhibition of molecular cloud and star formation in the outer disks of galaxies, can be understood in terms of this dependence. We present recent data on the edge-on galaxy NGC 891 that allow a comparison of the vertical distribution of CO and HI, and will therefore provide an independent test of these ideas.

Original languageEnglish (US)
Pages (from-to)211-214
Number of pages4
JournalAstrophysics and Space Science
Issue number3-4
StatePublished - 2004
Externally publishedYes


  • Galaxies: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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