This research project employs the WiFeS spectrograph on the ANU 2.3m telescope at Siding Spring to measure nebular chemical abundances in isolated gas-rich dwarf galaxies in the Local Volume.

The sample of Gas Rich Dwarf galaxies have been selected from the HIPASS Parkes Radio Telescope survey of neutral hydrogen 21cm radio emission in the southern sky. The sample comprises ~200 objects and provides a substantially complete set of such objects in the volume within 50 million light years of the Earth (the “Local Volume”).

The aim of this work is to understand better the relation between galaxy mass and the abundance of heavier elements (referred to as “metallicity”) for these objects, which is not well established at the low-mass end of the galaxy scale, and to see if there is evidence of a minimum level of nebular enrichment by supernovae. The galaxy sample provides several low-mass candidates which will allow us to explore this relation and to investigate the effect of isolation on metallicity.

In addition to these observations, as time and opportunity permit, we hope to observe some of the target galaxies using larger instruments in Australia and overseas to provide information on the existence and size of old stellar populations, and estimates of the baryonic mass of the sample galaxies and the Dark Matter they contain.

This work should contribute to an improved understanding of the dynamics and evolution of a range of dwarf galaxy types in the Local Volume.

For more information

• Nicholls, D. C., Dopita, M. A., Jerjen, H., & Meurer, G.R. (2011) The Small Isolated Gas Rich Irregular Dwarf (SIGRID) Galaxy Sample: Description and First Results, The Astronomical Journal, 142, 83.