Interstellar dust affects our view of the Universe, with half of the starlight emitted since the Big Bang being absorbed by dust grains and re-radiated in the Infra-Red. This thesis is concerned with understanding the origin of interstellar dust and determining the relative importance of different dust formation sites in the Universe. The sources and maximum amount of dust in early galaxies are investigated using published extended atmosphere models, stellar evolution tracks and nucleation conditions. A chemical evolution model is modified to include the estimated condensation efficiencies. The implications are investigated and we show that a supernovae source is required to produce large amounts of dust in galaxies. The atmospheres of AGB stars evolve too slowly to be responsible for high redshift dust. If SNe are not responsible for dust, then significant dust masses can only be generated at z > 5 by galaxies with very efficient star formation and no dust destruction. The first sub-millimetre analysis of the galactic remnant Kepler is presented with 0.3 3 M0 of dust, depending on the absorption properties. This a 1000 times more than previous Infra-red observations found. The sub-mm emission anti-correlates with the other wavelengths, including the warm dust and the most likely origin is from freshly synthesised dust in the supernova and dust formed from the interaction of the supernova shock with the ambient medium. Iron needles as a possible origin of the sub-mm emission are investigated. Finally, the sub-mm observations of the massive LBV star, rj Carinae are presented to show that the winds of massive stars may also be important contributors to the dust budget. We conclude that supernovae, or their massive star progenitors, are a dominant contributor to interstellar dust and make suggestions for future work.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:583392 |
| Date | January 2004 |
| Creators | Morgan, Haley Louise |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/54541/ |
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