[169.01] New Spitzer 4.5 $\mu$m Luminosities for Nearby Dwarf Irregular Galaxies

AAS 205th Meeting, 9-13 January 2005
Session 169 Dwarf Galaxies Near and Far and Some Starbursts
Oral, Thursday, January 13, 2005, 2:00-3:30pm, Pacific Salon 1

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[169.01] New Spitzer 4.5 \mum Luminosities for Nearby Dwarf Irregular Galaxies

H. Lee, D. C. Jackson, E. D. Skillman, R. D. Gehrz, E. Polomski, C. Woodward (Univ. of Minnesota)

Dwarf irregular galaxies display a correlation between metallicity and total luminosity. It is possible that this relationship arises from mass loss due to galactic winds. However, the relationship at optical wavelengths shows a large dispersion, and part of the dispersion may be due to variations in luminosity caused by variations in the star formation rate. Infrared luminosities are less affected by changes in the star formation rate, so it is of interest to study the infrared luminosity-metallicity relationship. We present new 4.5~\mum luminosities for nearby dwarf irregular galaxies observed under the Spitzer GTO program #128 (P. I. R.~Gehrz). For the first time, we construct an infrared luminosity-metallicity relationship for dwarf irregular galaxies. E.~D.~S. and H.~L. acknowledge partial support from a NASA LTSARP grant NAG~5--9221 and from the University of Minnesota. Support for this work was provided by NASA through contract #1256406 issued to R.~D.~G. by JPL/Caltech.

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