No description available.

The filamentary nebula RCW 86, identical with the non - thermal radio source MSH 14 - 63, is part of a supernova remnant. A group of OB stars is found near the radio source. The distance of the group is 2500 pc; this agrees well with the radio distance of the remnant. It is suggested that the remnant was formed by the explosion of a member of the group; the explosion occurred probably in 185 A. D.

Thesis (Ph. D.)--University of Sydney, 2001. / Includes tables. Title from title screen (viewed Apr. 22, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Degree awarded 2001; thesis submitted 2000. Includes bibliography. Also available in print form.

Thesis (Ph. D.)--University of Sydney, 1999. / Title from title screen (viewed Apr. 16, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.

Thesis (M. Sc.)--University of Sydney, 2001. / Title from title screen (viewed Apr. 23, 2008). Submitted in fulfilment of the requirements for the degree of Master of Science to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.

The explosion of a massive star results in an immense expulsion of energy and stellar debris (ejecta) that are heated to extremely high temperatures forming what is known as a super va remnant (SNR). Presented is a CHANDRA 0.5-10 keV X-ray study of the SNR RCW 103, a bright SNR that contains the unusual compact object 1E 161348-5055. This study is the first dedicated and complete imaging and spatially resolved spectroscopic study of the SNR aimed at addressing the intrinsic properties of the SNR, including the explosion energy, ambient density, age, and distance. The SNR's X-ray spectrum is dominated by thermal X-ray emission, requiring globally two components with temperatures at ~0.6 keV and ~0.27 keV and di fferent ionization timescales and abundances. We identify clumpy regions of enhanced abundances suggesting the presence of ejecta. The SNR age is estimated at 1.0-3.7 kyr at a distance of 3.1 kpc. / May 2016

We used the near-infrared [Fe II] emission line signature to detect supernova remnants (SNRs) in the nearby starburst galaxies NGC 1569, NGC 3738 and NGC 5253. The near-infrared narrow-band imaging program has led to the detection of 10 SNR candidates in NGC 1569, 7 in NGC 5253, and none in NGC 3738. A spatially extended component to the [Fe II] line emission is observed in NGC 1569 and NGC 5253. This component dominates the integrated [Fe II] luminosity in both galaxies, the compact sources accounting for 14% and 7% of the total [Fe II] luminosity of NGC 1569 and NGC 5253, respectively. Despite the starburst environment, the [Fe II] luminosity of the individual SNRs is two orders of magnitude lower than the luminosities observed for SNRs in M82. We find that the density and the structure of the interstellar medium is a more important factor than the starburst nature of a galaxy in determining the average [Fe II] luminosity of a SNR. We caution against the blind usage of supernova rate vs. [Fe II] luminosity relations, which are most often calibrated with the average luminosity of the remnants in M82. We suggest that a significant fraction of the ISM in NGC 1569 and NGC 5253 is under the influence of SNRs. This does not appear to be the case in M82, where the impact of the SNRs is limited to high density knots. Also, we find evidence for an [Fe II]-emitting lifetime as long as 105 yrs, which contrasts with the 104 yrs derived from SNRs in M82-like galaxies. We find that the [Fe II] morphology, and the integrated luminosity observed in our sample galaxies, can be reproduced from a [Fe II]-emitting SNR population, as long as the pre-shock density is kept as low as 1 cm −3. Higher pre-shock density models are strongly rejected. We find a supernova rate of 0.006 SN/yr for NGC 1569 and 0.005 SN/yr for NGC 5253. / Graduate

No description available.

Using two techniques not previously applied to Cassiopeia A (Cas A), we measure the reddening toward its expansion center. An estimate of AV from the near-IR [Fe II] lines is hampered by uncertain atomic data, though the spatial variation in their flux ratio allows relative measurement of the extinction in regions without previous optical estimates. We use a second technique based on the broad-band IR shape of the synchrotron emission, and find Aᵥ = 6.2 ± 0.6 for a knot 13" from the expansion center. Assuming a plausible lower limit on the apparent magnitude of the SN in outburst, the ⁵⁶Ni yield was 0.058 < M(Ni) < 0.16M⊙. With the ⁴⁴Ti mass from published gamma-ray observations, this implies a ⁴⁴Ca/ ⁵⁶Fe ratio consistent with the solar abundance. Recently published Spitzer Space Telescope IRS observations detect dust and line emission from cold gas interior to Cas A’s reverse shock. Using simple physical arguments and new hydrodynamic, non-equilibrium photoionization calculations, we infer the physical conditions in this material. We find that the mid-IR bright clumps are photoionized by the SNR shocks, over-dense relative to the expected average in the interior of the remnant, and have abundances consistent with incomplete oxygen burning. The lack of detectable iron lines indicates that any Si-burning material still interior to the reverse shock must be far more tenuous than the clumps of O-burning ashes. Finally, we present calculations from a new multi-dimensional hydrodynamics and non-equilibrium ionization and cooling code designed to model the emission from SNR shocks. Two-dimensional simulations of a shock-cloud interaction in a pure-oxygen plasma, with flow parameters relevant to Cas A, show a wider range of temperatures and ionization states than is typical in single-zone or 1D calculations, indicating that fluid and cooling instabilities play a role in producing the observed spectra of radiative shocks in metal-rich gas.

A sample of 9 small-diameter radio sources has been selected from the Molonglo Galactic Plane Survey (MGPS) and observed with the Australia Telescope Compact Array (ATCA) in the radio recombination line (RRL) at 5 GHz, in a search for young Galactic SNRs. Since the RRL emission is an unambiguous indicator of a thermal source, this method has been used to eliminate HII regions from the selected sample. In addition, the IRAS and MSX infrared data and spectral index measurements have been combined with the RRL studies to distinguish thermal and non-thermal sources in the selected sample. One source (G282.8-1.2) is identified here as a possible new young Galactic supernova remnant, based on its relatively weak infrared emission, steep radio spectrum and possible x-ray emission. However, the ATCA data are inconclusive and further studies are needed to confirm this result. Radio recombination line emission (H107 alpha) has been detected in 3 of the selected sources, eliminating them from the sample of SNR candidates. In addition, the parameters of the RRL emission from the identified HII regions have been used to estimate their properties. The RRL data are inconclusive for the remaining low brightness, extended sources in the sample. However, some of these sources are likely to be thermal HII regions according to the infrared and spectral index data. The selected method for distinguishing thermal and non-thermal Galactic radio sources seems promising. The selected ATCA configuration was appropriate for imaging relatively bright, compact sources, but a slightly modified observing technique is needed to successfully image low surface brightness, extended sources.