AAS 201st Meeting, January, 2003
Session 13. Galaxy - Structure
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[13.01] Stellar Mass-to-Light Ratios and Rotation Curves of Spiral Galaxies

R.S. de Jong (STScI), E.F. Bell (MPIA), S. Courteau (UBC), R.P. Olling (USNO)

We present a simple technique to estimate mass-to-light (M/L) ratios of stellar populations in local universe galaxies based on two broadband photometry measurements, i.e. a color-M/L relation. The method is significantly better than using a fixed M/L, even in the near-IR. The main uncertainty stems from the assumed stellar IMF, which results in a zero-point uncertainty of the color-M/L relation. We constrain the zero-point using maximum disk rotation curve limits.

We apply the color-M/L relation to galaxy rotation curves, using a large set of galaxies that span a large range in Hubble type, luminosity and scale size and that have accurately measured HI rotation curves. We have obtained new accurate optical and near-IR surface photometry of these galaxies as well as H\alpha rotation curves. Using the color-M/L relation we construct stellar mass models of the galaxies. We subtract all known mass components from the observed rotation curves to reveal the dark matter contribution to the rotation curves. Finally, using these dark matter rotation curves we investigate dark matter scaling relations for our set of galaxies.

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