%0 Journal Article
%A Gil De Paz, Armando
%T Embedded star formation in S^(4)G galaxy dust lanes
%D 2014
%@ 0004-637X
%U https://hdl.handle.net/20.500.14352/35012
%X Star-forming regions that are visible at 3.6 μm and Hα but not in the u, g, r, i, z bands of the Sloan Digital Sky Survey are measured in five nearby spiral galaxies to find extinctions averaging ~3.8 mag and stellar masses averaging ~5 × 10^4 M_☉. These regions are apparently young star complexes embedded in dark filamentary shock fronts connected with spiral arms. The associated cloud masses are ~10^7 M_☉. The conditions required to make such complexes are explored, including gravitational instabilities in spiral-shocked gas and compression of incident clouds. We find that instabilities are too slow for a complete collapse of the observed spiral filaments, but they could lead to star formation in the denser parts. Compression of incident clouds can produce a faster collapse but has difficulty explaining the semi-regular spacing of some regions along the arms. If gravitational instabilities are involved, then the condensations have the local Jeans mass. Also in this case, the near-simultaneous appearance of equally spaced complexes suggests that the dust lanes, and perhaps the arms too, are relatively young.
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