RSAA Colloquia / Seminars / Feast-of-Facts: Tuesday, 03 January 2017, 11:00-12:00; Duffield Lecture Theatre

Tye Young

"Physical Properties of low mass Galaxies in the Local Volume - End of Thesis Colloquium"

The motivation of this research came from a desire to accurately trace the underlying stellar distributions of low mass irregular galaxies in the Local Volume and utilize the derived properties in various avenues of research. To this effect, deep H-band surface photometry and analysis of 40 Local Volume galaxies was performed, a sample primarily composed of dwarf irregulars in the Cen A group, obtained using the IRIS2 detector at the 3.9m Anglo- Australian Telescope. The imagery probes to a surface brightness of 25 mag per square arcsec, reaching a 40 times lower stellar density than the Two Micron All Sky Survey (2MASS) which had insufficient image depth to study dwarf galaxies in the NIR. Given available evidence in the literature, and from analysis of the NIR imagery it was suspected that the structural properties of irregular galaxies were similar to other dwarf sub-types. I tested this suspicion through structure-luminosity relationships for the low mass irregulars in the sample and dwarf ellipticals and spheroidal galaxies obtained from other catalogues. I demonstrate that a significant fraction of the Local Volume dwarf irregular population have underlying structural properties similar to both Local Volume and Virgo Cluster dwarf ellipticals. Spatially resolved Hi studies of dwarf galaxies have provided a wealth of precision data. However these high quality resolved observations are only possible for handful of dwarf galaxies in the Local Volume. Future Hi surveys are unlikely to improve the current situation. I therefore explored a method for estimating the surface density of the atomic gas from global Hi parameters, which are conversely widely available.