Theoretical studies of massive stars near the Eddington limit

  • Gautham Narayana Sabhahit

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Massive stars form an integral part of many astrophysical research fields. Their continuous winds and violent supernova explosions have a direct impact on the dynamic and chemical evolution of galaxies. Furthermore, massive stars leave behind remnants such as neutron stars or black holes, thus contributing significantly to gravitational wave studies. Despite their importance to astrophysics, massive star modelling is plagued by inherent uncertainties due to the uncertain physics of mass loss and interior mixing, that challenge our understanding of these objects.

Of particular interest are the massive stars close to radiative instability called the Eddington limit and how that impacts their evolution and end-fates. In this thesis, I compute stellar evolution models as well as hydro-dynamically consistent wind models of massive stars close to their Eddington limit. The Eddington limit in the envelopes of luminous red supergiants is examined in chapter 3 following the recent discovery of a potential metallicity independent Humphreys-Davidson limit. The thesis also presents a new mass-loss framework based on the concept of transition mass loss from Vink and Gräfener (2012) which is tailored to study the evolution of very massive stars in different metallicity environments (chapters 4 - 6). Grids of single massive star models up to 500 𝑀⊙ are presented that implement optically-thick wind physics with predictions for their end-fates and a possible explanation for the apparently low incidence of pair-instability supernovae in the local Universe.

Chapters 1 and 2 provide the necessary pre-requisite material for the research chapters, with conclusions and future work outlined in chapter 7.
Date of AwardDec 2023
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsArmagh Observatory and Planetarium
SupervisorJorick Vink (Supervisor) & Gavin Ramsay (Supervisor)

Keywords

  • Stars
  • mass-loss
  • massive
  • stars evolution
  • early type stars

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