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The Interplay Between Massive Stars and their Associated Nebulae within the Milky Way and Large Magellanic Cloud

Doran, Emile (2014) The Interplay Between Massive Stars and their Associated Nebulae within the Milky Way and Large Magellanic Cloud. PhD thesis, University of Sheffield.

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Abstract

This study seeks to enhance our understanding of the relationship between massive stars and their environment. New William Herschel Telescope (WHT) imaging and spectroscopy of 13 outer Milky Way HII regions is presented in Chapter 2. Properties of the nebulae and stars were separately determined and compared for consistency. Results showed that the ionising photons from the star were not accounted for by some nebulae, by as much as ~85% in some cases. This fraction depended on the age of the region and indicated that photons were either escaping the region or being absorbed by dust. The VLT-FLAMES Tarantula Survey (VFTS) is introduced in Chapter 3 with analyses of the emission line stars. Spectroscopic variabilities were investigated to improve understanding of their binary nature. In comparison to O2 stars, their spectral lines were found to be less reliable for determining radial velocities. Further derivations of their stellar properties were made via a series of template model atmospheres. A census of the hot luminous stars within 30 Doradus of the LMC is compiled in Chapter 4, based on literature results, largely drawn from the VFTS. They were selected through specific photometric criteria of which 500 stars had spectroscopic classification while a further 222 were classified via their photometry. The spectroscopic completeness of hot luminous stars was estimated at ~85% although this fell towards the central cluster due to crowding. In Chapter 5, the integrated ionising output and wind luminosity of the stellar population was determined with the most massive stars (>100Msun) found to make the highest contributions, and just ten stars providing 28\% of the integrated value in both cases. Comparisons to the population synthesis code Starburst99 showed significant underestimates in the integrated feedback if such massive stars were omitted. The stellar ionising output of 30 Doradus exceeded that derived from the nebula, indicating that ~6% of ionising photons were escaping the region. A brief summary and potential avenues for future work are presented in Chapter 6.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Physics and Astronomy (Sheffield)
Identification Number/EthosID: uk.bl.ethos.617206
Depositing User: Mr Emile Doran
Date Deposited: 18 Aug 2014 14:33
Last Modified: 03 Oct 2016 11:17
URI: http://etheses.whiterose.ac.uk/id/eprint/6628

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