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    National Tsing Hua University Institutional Repository > 歷任校長 > 徐遐生 (2002-2006) > 期刊論文 >  Branch, spur, and feather formation in spiral galaxies


    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/80934


    Title: Branch, spur, and feather formation in spiral galaxies
    Authors: Chakrabarti, S.;Laughlin, G.;Shu, F.H.
    教師: 徐遐生
    Date: 2003
    Publisher: American Astronomical Society
    Relation: ASTROPHYSICAL JOURNAL, American Astronomical Society, Volume 596, Issue 1, Part 1, OCT 10 2003, Pages 220-239
    Keywords: galaxies: spiral
    galaxies: structure
    hydrodynamics
    instabilities
    stellar dynamics
    Abstract: We use hydrodynamic simulations to investigate the response of geometrically thin, self-gravitating, singular isothermal disks of gas to imposed rigidly rotating spiral potentials. By minimizing reflection-induced feedback from boundaries, and by restricting our attention to models where the swing parameter Xsimilar to10, we minimize the swing amplification of global normal modes even in models where Toomre's Q(g)similar to1-2 in the gas disk. We perform two classes of simulations: short-term ones over a few galactic revolutions where the background spiral forcing is large, and long-term ones over many galactic revolutions where the spiral forcing is considerably smaller. In both classes of simulations, the initial response of the gas disk is smooth and mimics the driving spiral field. At late times, many of the models evince substructure akin to the so-called branches, spurs, and feathers observed in real spiral galaxies. We comment on the parts played respectively by ultraharmonic resonances, reflection off internal features produced by nonlinear dredging, and local, transient, gravitational instabilities within spiral arms in the generation of such features. Our simulations reinforce the idea that spiral structure in the gaseous component becomes increasingly flocculent and disordered with the passage of time, even when the background population of old disk stars is a grand-design spiral. We speculate that truly chaotic behavior arises when many overlapping ultraharmonic resonances develop in reaction to an imposed spiral forcing that has itself a nonlinear, yet smooth, wave profile.
    Relation Link: http://aas.org/
    URI: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/80934
    Appears in Collections:[ 徐遐生 (2002-2006)] 期刊論文
    [物理系] 期刊論文

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