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Date and Time of the Query: 2019-04-20 T01:50:21 PDT
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For refcode 1993AJ....106.1771K:
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Copyright by American Astronomical Society. Reproduced by permission
1993AJ....106.1771K KINEMATIC REGULATION OF STAR FORMATION IN INTERACTING GALAXIES WILLIAM C. KEEL Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscalcosa, Alabama 35487-0324 Electronic mail: keel@bildad.astr.ua.edu Received 1993 June 8; revised 1993 July 30 ABSTRACT Kinematic data for a geometrically-selected set of spiral galaxies in pairs are presented, and analyzed for correlations between indicators of star formation and indices of orbital type and extent of kinematic disturbance. Both nuclear and global star formation rate are connected to kinematic disturbance with the kind and degree of disturbance more important than either projected separation or relative directions of galaxy spin and companion orbit. Enhanced star formation is found for galaxies with large areas of solid-body rotation and for galaxies with more general kinds of disturbed velocity structure, with the highest levels occurring in a set of galaxies distinguished by anomalously small overall velocity amplitude. The strongest correlation is between star formation rate (SFR) and amplitude of velocity disturbance, from rotation curves, when the velocity disturbance is scaled by the galaxy rotation velocity. Triggered star formation is more sensitive to galaxy dynamics than to strictly local phenomena such as cloud disruption velocities. Comparison with various models for the enhanced SFR in interacting systems shows that cloud-collision processes cannot account for the strong starbursts in retrograde systems, and models relying on interactions between different phases of the interstellar medium similarly require too many direct collisions between galaxy disks. Schemes involving gravitational instability of the disk driven initially by the external perturbation fare best; such instability can then drive the rates of other processes such as cloud collisions, possibly in a cascadelike series. Solid-body kinematics appear more important than the presence of a stellar bar in this connection. Using a new set of classifications from uniform CCD images, there is a better correlation between disturbed kinematics and morphological disturbance of individual galaxies than with pair interaction types in the Karachentsev catalog, though the relationship is not one-to-one. There is a substantial population of pairs with disturbed kinematics but not (yet?) disturbed forms. The kinds of disturbance found from direct and retrograde encounters match well the predictions of n-body calculations for each kind of encounter.
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