TIGHTLY CORRELATED H I AND FUV EMISSION IN THE OUTSKIRTS OF M83

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/720/1/L31· OSTI ID:21452846

Bigiel, F; Blitz, L ^[1]; Leroy, A ^[2]; Seibert, M; Madore, B ^[3]; Walter, F ^[4]; Thilker, D ^[5]

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1. Department of Astronomy, Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 (United States)
2. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
3. Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)
4. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)
5. Center for Astrophysical Sciences, Johns-Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

We compare sensitive H I data from The H I Nearby Galaxy Survey and deep far-ultraviolet (FUV) data from the Galaxy Evolution Explorer in the outer disk of M83. The FUV and H I maps show a stunning spatial correlation out to almost 4 optical radii (r {sub 25}), roughly the extent of our maps. This underscores that H I traces the gas reservoir for outer-disk star formation (SF), and it implies that massive (at least low level) SF proceeds almost everywhere that H I is observed. Whereas the average FUV intensity steadily decreases with increasing radius before leveling off at {approx}1.7 r {sub 25}, the decline in H I surface density is more subtle. Low H I columns ({approx_lt}2 M {sub sun} pc{sup -2}) contribute most of the mass in the outer disk, which is not the case within r {sub 25}. The time for SF to consume the available H I, inferred from the ratio of H I to FUV intensity, rises with increasing radius before leveling off at {approx}100 Gyr, i.e., many Hubble times, near {approx}1.7 r {sub 25}. Assuming that the relatively short H{sub 2} depletion times observed in the inner parts of galaxies hold in outer disks, the conversion of H I into bound, molecular clouds seems to limit SF in outer galaxy disks. The long consumption times suggest that most of the extended H I observed in M83 will not be consumed by in situ SF. However, even these low SF rates are enough for moderate chemical enrichment in a closed outer disk to be expected.

• OSTI ID: 21452846
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 720; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
EVOLUTION
FAR ULTRAVIOLET RADIATION
GALACTIC EVOLUTION
GALAXIES
HYDROGEN
MASS
NONMETALS
RADIATIONS
STARS
ULTRAVIOLET RADIATION