H II Regions in Sculptor Group Dwarf Galaxies

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Session 60 -- HII Regions
Display presentation, Thursday, 9:20-4:00, Pauley Room

[60.07] H II Regions in Sculptor Group Dwarf Galaxies

Bryan W. Miller (UWash)

The first results of a thesis project to study the star formation histories of dwarf galaxies in the nearby Sculptor Group are presented. The first stage of this project involves determining the global current star-formation rates in these galaxies from H$\alpha$ imaging and their oxygen abundances from nebular spectroscopy. Only three of ten galaxies in the sample have well detected H~II regions, and spectroscopy of one of these galaxies reveals that it is really a background spiral with $V_{\odot} \sim 1500$ km s$^{-1}$. ESO 471-G06 has $\log(L_{H\alpha}) \sim 38.2$ assuming D = 3 Mpc while A143 has $\log(L_{H\alpha}) \sim 38.9$ assuming D = 4 Mpc. Distances were assigned based on known distances to other Sculptor Group galaxies, known H~I velocities, and the degree to which these galaxies resolved into stars in broad-band images. These values give total star-formation rates of $1.6 \times 10^{-3}$ M$_{\odot}$ yr$^{-1}$ and $7.5 \times 10^{-3}$ M$_{\odot}$ yr$^{-1}$, respectfully, which are comparable to the star-formation rates for the M81 Group dwarfs Ho~I and M81dB (Hodge and Miller 1992). Further work on these galaxies will involve broad-band surface photometry and photometry of the resolved giants.

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