Abstracts Astronomy & Space Science

The complex nature of the ISM in the SMC

by Snezana Stanimirovic

This thesis presents the results of a combination of new observations with the Parkes telescope of neutral hydrogen (HI) in the Small Magellanic Cloud (SMC) with an Australia Telescope Compact Array aperture synthesis mosaic. The data are used to study the HI distribution and mass, the velocity field and rotation curve of the SMC, as well as to probe the 3-D structure of the SMC. A kinematic study of the HI data reveals the existence of three supergiant shells which were previously undetectable in the ATCA data alone. The HI spatial power spectrum has been investigated over a range of contiguous scale sizes wider than those previously achieved in any other galaxy. This thesis also demonstrates that the infrared data obtained with the Infrared Astronomical Satellite for the SMC can be successfully reconstructed with much higher resolution using the Pyramid Maximum Entropy algorithm. The new infrared (IR) data are used to study the integrated IR spectrum, the dust temperature and dust column density in the SMC. The high resolution HI and IR data enable an investigation of the spatial correlation of dust and gas and the assumption of the dust and gas being well-mixed in the ISM. The spatial power spectrum of the dust column density shows that, as with the HI power spectrum, there is no preferred scale size for dust clouds. The remarkable similarity of the spatial power spectra for the HI and dust column density distributions suggests a unique hierarchical structure organisation for the ISM in the SMC. Such an organisation is likely to be governed by the Kolmogorov type turbulence and could be described by fractal nature with the volume fractal dimension of 2.4. Doctor of Philosophy (PhD)