The star formation threshold in NGC 6822

W. J.G. De Blok*, F. Walter

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    53 Citations (Scopus)


    We investigate the star formation threshold in NGC 6822, a nearby Local Group dwarf galaxy, on subkiloparsec scales using high-resolution, wide-field, deep H I, Hα, and optical data. In a study of the H I velocity profiles we identify cool and warm neutral components in the interstellar medium of NGC 6822. We show that the velocity dispersion of the cool component (∼4 km s-1) when used with a Toomre Q-criterion gives an optimal description of ongoing star formation in NGC 6822 superior to that using the more conventional dispersion value of 6 km s-1. However, a simple constant surface density criterion for star formation gives an equally superior description. We also investigate the two-dimensional distribution of Q and the star formation threshold and find that these results also hold locally. The range in gas density in NGC 6822 is much larger than the range in critical density, and we argue that the conditions for star formation in NGC 6822 are fully driven by this density criterion. Star formation is local, and in NGC 6822 global rotational or shear parameters are apparently not important.

    Original languageEnglish
    Pages (from-to)363-374
    Number of pages12
    JournalAstronomical Journal
    Issue number1
    Publication statusPublished - Jan 2006


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