{"id":{"repo_id":"liverpool-jm","oai_identifier":"oai:researchonline.ljmu.ac.uk:10975"},"canonical_url":"https://search.dev.ndltd.org/etd/liverpool-jm/oai:researchonline.ljmu.ac.uk:10975","repository":{"repo_id":"liverpool-jm","name":"Liverpool Jon Moores University","base_url":"https://researchonline.ljmu.ac.uk/cgi/oai2"},"display":{"title":"THE PROGENITORS OF TYPE IIP SUPERNOVAE","abstract":"Mass-loss prior to core collapse is arguably the most important factor affecting the evolution of a massive star across the Hertzsprung-Russel (HR) diagram, making it the key to understanding what mass-range of stars produce supernova (SN), and how these explosions will appear. It is thought that most of the mass-loss occurs during the red supergiant (RSG) phase, when strong winds dictate the onward evolutionary path of the star and potentially remove the entire H-rich envelope. Uncertainty in the driving mechanism for RSG winds means the mass-loss rate (\\mdot) cannot be determined from first principles, and instead, stellar evolution models rely on empirical recipes to inform their calculations. At present, the most commonly used \\mdot-prescription comes from a literature study, whereby many measurements of mass-loss were compiled. The sample sizes are small ($<$10 stars), highly heterogeneous in terms of mass and metallicity, and have very uncertain distances from observations and analysis techniques that at best provide order-of-magnitude estimates compared to what is possible today. The relation itself contains large internal scatter, which could be the difference between a star losing its entire H-envelope, or none of it at all. More modern efforts to update the RSG mass-loss rate prescription rely on samples which suffer from statistical biases, for example by selecting objects based on mid-IR brightness or circumstellar maser emission, and hence are inevitably biased towards higher mass-loss rate objects. It is the aim of this thesis to overhaul our understanding of RSG mass-loss. By selecting RSGs in clusters, where the initial mass and metallicity are known, I will be able to observe how mass-loss changes as the star approaches SN and compare this to what is currently implemented in stellar evolutionary models. Ultimately, I will measure \\mdot\\ values and luminosities for RSGs in 5 different clusters of varying ages, thus targeting RSGs of different initial masses. I will then combine these mass-loss rate-luminosity relations to derive a new initial mass-dependent mass-loss rate, which can be implemented into stellar evolutionary models.","abstract_html":"Mass-loss prior to core collapse is arguably the most important factor affecting the evolution of a massive star across the Hertzsprung-Russel (HR) diagram, making it the key to understanding what mass-range of stars produce supernova (SN), and how these explosions will appear. It is thought that most of the mass-loss occurs during the red supergiant (RSG) phase, when strong winds dictate the onward evolutionary path of the star and potentially remove the entire H-rich envelope. Uncertainty in the driving mechanism for RSG winds means the mass-loss rate (\\mdot) cannot be determined from first principles, and instead, stellar evolution models rely on empirical recipes to inform their calculations. At present, the most commonly used \\mdot-prescription comes from a literature study, whereby many measurements of mass-loss were compiled. The sample sizes are small ($&lt;$10 stars), highly heterogeneous in terms of mass and metallicity, and have very uncertain distances from observations and analysis techniques that at best provide order-of-magnitude estimates compared to what is possible today. The relation itself contains large internal scatter, which could be the difference between a star losing its entire H-envelope, or none of it at all. More modern efforts to update the RSG mass-loss rate prescription rely on samples which suffer from statistical biases, for example by selecting objects based on mid-IR brightness or circumstellar maser emission, and hence are inevitably biased towards higher mass-loss rate objects. It is the aim of this thesis to overhaul our understanding of RSG mass-loss. By selecting RSGs in clusters, where the initial mass and metallicity are known, I will be able to observe how mass-loss changes as the star approaches SN and compare this to what is currently implemented in stellar evolutionary models. Ultimately, I will measure \\mdot\\ values and luminosities for RSGs in 5 different clusters of varying ages, thus targeting RSGs of different initial masses. I will then combine these mass-loss rate-luminosity relations to derive a new initial mass-dependent mass-loss rate, which can be implemented into stellar evolutionary models.","abstract_has_math":true,"creators":["Beasor, E"],"institution":"Liverpool John Moores University","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Davies, B"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-06","date_published":"2019-06","updated_at":"2026-07-24T06:30:28Z","subjects":["QB Astronomy","QC Physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://doi.org/10.24377/LJMU.t.00010975","outbound_label":"DOI","outbound_source":"dc:identifier.doi"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Davies, B"]},{"key":"dc:creator","label":"Author","values":["Beasor, E"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-06-11"]},{"key":"dc:date.issued","label":"Date","values":["2019-06"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Astrophysics Research Institute"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Liverpool John Moores University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://researchonline.ljmu.ac.uk/id/eprint/10975/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["QB Astronomy","QC Physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.24377/LJMU.t.00010975"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://researchonline.ljmu.ac.uk/id/eprint/10975/1/Thesis-3.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Mass-loss prior to core collapse is arguably the most important factor affecting the evolution of a massive star across the Hertzsprung-Russel (HR) diagram, making it the key to understanding what mass-range of stars produce supernova (SN), and how these explosions will appear. It is thought that most of the mass-loss occurs during the red supergiant (RSG) phase, when strong winds dictate the onward evolutionary path of the star and potentially remove the entire H-rich envelope. Uncertainty in the driving mechanism for RSG winds means the mass-loss rate (\\mdot) cannot be determined from first principles, and instead, stellar evolution models rely on empirical recipes to inform their calculations. At present, the most commonly used \\mdot-prescription comes from a literature study, whereby many measurements of mass-loss were compiled. The sample sizes are small ($<$10 stars), highly heterogeneous in terms of mass and metallicity, and have very uncertain distances from observations and analysis techniques that at best provide order-of-magnitude estimates compared to what is possible today. The relation itself contains large internal scatter, which could be the difference between a star losing its entire H-envelope, or none of it at all. More modern efforts to update the RSG mass-loss rate prescription rely on samples which suffer from statistical biases, for example by selecting objects based on mid-IR brightness or circumstellar maser emission, and hence are inevitably biased towards higher mass-loss rate objects. It is the aim of this thesis to overhaul our understanding of RSG mass-loss. By selecting RSGs in clusters, where the initial mass and metallicity are known, I will be able to observe how mass-loss changes as the star approaches SN and compare this to what is currently implemented in stellar evolutionary models. Ultimately, I will measure \\mdot\\ values and luminosities for RSGs in 5 different clusters of varying ages, thus targeting RSGs of different initial masses. I will then combine these mass-loss rate-luminosity relations to derive a new initial mass-dependent mass-loss rate, which can be implemented into stellar evolutionary models."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["THE PROGENITORS OF TYPE IIP SUPERNOVAE"]}]}],"canonical_facts":{"dc:contributor":["Davies, B"],"dc:creator":["Beasor, E"],"dc:date":["2019-06-11"],"dc:date.issued":["2019-06"],"dc:description.abstract":["Mass-loss prior to core collapse is arguably the most important factor affecting the evolution of a massive star across the Hertzsprung-Russel (HR) diagram, making it the key to understanding what mass-range of stars produce supernova (SN), and how these explosions will appear. It is thought that most of the mass-loss occurs during the red supergiant (RSG) phase, when strong winds dictate the onward evolutionary path of the star and potentially remove the entire H-rich envelope. Uncertainty in the driving mechanism for RSG winds means the mass-loss rate (\\mdot) cannot be determined from first principles, and instead, stellar evolution models rely on empirical recipes to inform their calculations. At present, the most commonly used \\mdot-prescription comes from a literature study, whereby many measurements of mass-loss were compiled. The sample sizes are small ($<$10 stars), highly heterogeneous in terms of mass and metallicity, and have very uncertain distances from observations and analysis techniques that at best provide order-of-magnitude estimates compared to what is possible today. The relation itself contains large internal scatter, which could be the difference between a star losing its entire H-envelope, or none of it at all. More modern efforts to update the RSG mass-loss rate prescription rely on samples which suffer from statistical biases, for example by selecting objects based on mid-IR brightness or circumstellar maser emission, and hence are inevitably biased towards higher mass-loss rate objects. It is the aim of this thesis to overhaul our understanding of RSG mass-loss. By selecting RSGs in clusters, where the initial mass and metallicity are known, I will be able to observe how mass-loss changes as the star approaches SN and compare this to what is currently implemented in stellar evolutionary models. Ultimately, I will measure \\mdot\\ values and luminosities for RSGs in 5 different clusters of varying ages, thus targeting RSGs of different initial masses. I will then combine these mass-loss rate-luminosity relations to derive a new initial mass-dependent mass-loss rate, which can be implemented into stellar evolutionary models."],"dc:format":["text"],"dc:identifier.doi":["10.24377/LJMU.t.00010975"],"dc:identifier.uri":["https://researchonline.ljmu.ac.uk/id/eprint/10975/1/Thesis-3.pdf"],"dc:publisher.department":["Astrophysics Research Institute"],"dc:publisher.institution":["Liverpool John Moores University"],"dc:relation.isreferencedby":["https://researchonline.ljmu.ac.uk/id/eprint/10975/"],"dc:subject":["QB Astronomy","QC Physics"],"dc:title":["THE PROGENITORS OF TYPE IIP SUPERNOVAE"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T06:30:28Z"}