Bibcode
Jogee, S.; Laine, S.; Shlosman, I.; Scoville, N. Z.; Knapen, J. H.; Englmaier, P.; Wilson, C. D.
Bibliographical reference
American Astronomical Society, 199th AAS Meeting, #72.04; Bulletin of the American Astronomical Society, Vol. 33, p.1416
Advertised on:
12
2001
Citations
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Description
We present a multi-wavelength study of the gas dynamics and star
formation in the grand-design spiral galaxy NGC 5248, illustrating how
coupled dynamical mechanisms can generate spiral structures from tens of
kpc to hundreds of pc, drive disk evolution, and fuel star formation on
progressively smaller scales. Although to date NGC 5248 has been
classified as unbarred or claimed to host a weak bar less than 2.2 kpc
in size, we argue that its prominent large-scale spiral structures are
driven by a stellar bar whose corotation radius and semi-major axis are
at least 70'' (5.1 kpc). We confirm this prediction with new
observations. In this barred potential, our high resolution (1.9'' x
1.4'') OVRO CO (J=1->0) map reveals two massive trailing molecular
spiral arms which can be followed from 1.3 kpc to 375 pc, and feed a
circumnuclear ring of HII regions and super star clusters. A
weakly-spiral molecular gas feature and a dust spiral extend between
this starburst ring and a second Hα ring of radius 95 pc. To
account for the observed morphology within the inner kpc, we compare NGC
5248 to theoretical models of gaseous spiral density waves and nested
dynamically decoupled bars. We also find that the emission-line
complexes which have the largest extinction and show evidence of hosting
the youngest embedded stellar clusters coincide with the brightest CO
peaks. In contrast, many of the young visible clusters with moderate
extinction are associated with little CO emission and are surrounded by
shells and bubbles of ionized gas. This suggests a scenario where young
star-forming regions form within dense gas complexes, whereupon stellar
winds and supernovae very efficiently clear out gas on timescales less
than a few megayears. This work is supported by NSF grant AST 99-81546,
and a grant from the K. T. and E. L. Norris Foundation