AAS 197, January 2001
Session 76. Galaxy Evolution I
Display, Wednesday, January 10, 2001, 9:30am-7:00pm, Exhibit Hall

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[76.01] A Successful Automated Search for Crouching Giants

J.E. Cabanela (Saint Cloud State University), J.M. Dickey (University of Minnesota)

Much effort has been expended during the last two decades on the search for Low Surface Brightness galaxies (LSBs), the galaxies Disney called ``Crouching Giants,'' which may be a dominant mass repository in the universe. The difficulty in gathering information on a significant population of LSBs lies in the time-consuming nature of identifying LSB candidates. To date, all survey-based searches for LSBs have involved manual inspections of plate-based material or optical CCD observations.

We have conducted the first successful automated search for H{\tt I}-rich galaxies (including LSBs) using the Minnesota Automated Plate Scanner (APS) Catalog of the POSS I. We identified H{\tt I}-rich candidates by selecting galaxies located on the ``blue edge'' of an O-E vs. E color-magnitude diagram from the APS Catalog. Subsequent 21-cm observations on the upgraded Arecibo 305m dish showed that over 50% of our observed candidates were H{\tt I}-rich with MH{\tt I}/LB ranging from 0.1 to 4.8 (in solar units). These MH{\tt I}/LB values are comparable to those of LSB candidates selected by manual means. Comparison of our candidate galaxies with known LSB galaxies shows that they have similar bivariate brightness distributions as well as other optical properties. Furthermore, examination of existing LSB catalogs shows that over 65% of LSBs are located on the ``blue edge,'' whereas only 10% of the general APS galaxy population has O-E values this low. Known LSB galaxies on the O-E ``blue edge'' include several LSBs with red B-V colors from O'Neil, Bothun, and Schombert (2000), indicating our bandpasses are critical in the segregation of these LSB candidates from the general population.

We have determined the physical basis for the success of these simple search criteria, which is tied to the low current star formation rate of LSBs. The details of the search algorithm and guidelines of how to apply it to other existing surveys, such as the SDSS, will be provided.

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

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