NOAO >   Observing Info >   Approved Programs >   2003B-0153

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Proposal Information for 2003B-0153


PI: Rebecca Grouchy, University of Alabama, grouc001@bama.ua.edu
Address: Physics Department, Box 870324, Tuscaloosa, Alabama 35487, USA

CoI: Ronald Buta, University of Alabama

Title: Properties of Non-Barred Ringed Galaxies

Abstract: Rings of star formation are a common property of the morphology of barred (SAB and SB) galaxies. These features are easily explained in terms of gas accumulation at resonances, under the continuous action of gravity torques from the bar pattern. However, it is an interesting enigma that a nonnegligible fraction of \it nonbarred (SA) galaxies also shows rings, sometimes even multiple rings just as in barred galaxies. The existence of these objects strongly suggests an evolutionary process in which the bar dissolved, leaving behind any rings it may have generated while it was strong. It has also been known for some time that the rings of nonbarred galaxies have a much greater dispersion of metric properties than do those in barred galaxies. This suggests that an additional mechanism, possibly tidal interaction, may be involved in producing rings in nonbarred galaxies that is less relevant in barred galaxies. We are proposing to carry out a survey to obtain optical and velocity data of a significant sample of nonbarred ringed galaxies to delineate their properties and establish criteria for recognizing "ex-barred" galaxies and interaction driven galactic rings. The images will be used to (1) characterize the morphologies of nonbarred ringed galaxies in terms! of the typical features seen and the appearance of the rings; (2) examine the the color distribution and star formation properties of the rings; (3) detect weak, possibly fading bar structures; and (4) measure the underlying bulge and disk structure. The data will be compared with the significant body of information already available on ringed barred galaxies to determine how the two classes of objects are related.


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