AAS 205th Meeting, 9-13 January 2005
Session 60 Secular Evolution Potpourri: Star Formation to Galactic Structures
Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall

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[60.17] Disk Stability and the Fastest Rotators: First Results

K. Spekkens, R. Giovanelli (Cornell University)

We present initial results from a study to evaluate the role of disk stability in setting the observed upper bound to spiral galaxy rotational velocities (Vrot ~400 km/s). The canonical galaxy formation paradigm leads to scaling relations between Vrot and other structural properties of disks. Within this framework disks are stable if the spin parameter of the halo (\lambda) exceeds the ratio of the disk mass to that of the halo (md). An upper limit to Vrot then arises because massive halos retain all of their baryons during disk formation, and thus few have \lambda large enough to satisfy the stability requirement. We have obtained high-quality H\alpha spectra, HI aperture synthesis maps and accurate I-band images for 8 of the fastest known rotators, which are being used in an attempt to measure \lambda and md via the scaling relations to test this hypothesis. We discuss a first analysis of this data, as well as the observed scaling relations for a sample of over 4000 spiral galaxies from the SFI++ database maintained at Cornell. This work is partially funded by NSF grants AST-0307396 and AST-0307661.

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The author(s) of this abstract have provided an email address for comments about the abstract: spekkens@astro.cornell.edu

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