Modelling supermassive primordial stars with MESA

Nicholas Herrington, Daniel Whalen, Tyrone E. Woods

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Supermassive stars forming at z ∼ 15–20 are one of the leading contenders for the origin of the first quasars, over 200 of which have now been discovered at z > 6. These stars likely form in pristine, atomically cooled haloes immersed in strong Lyman-Werner UV backgrounds or in highly supersonic baryon streaming flows. Atomic cooling triggers catastrophic baryon collapse capable of building up stars at rates of up to ∼1 M⊙ yr−1. Here we examine the evolution of supermassive stars with a much larger and finer grid of accretion rates than in previous studies with the MESA stellar evolution code. We find that their final masses range from 3.5 × 103 M⊙ - 3.7 × 105 M⊙ at accretion rates of 0.001 M⊙ yr−1 - 1 M⊙ yr−1, respectively. We also find that supermassive star evolution diverges at accretion rates of 0.01 M⊙ yr−1 - 0.02 M⊙ yr−1, above which they evolve as cool red hypergiants along the Hayashi track and collapse via the general relativistic instability during central hydrogen burning, and below which they evolve as hot blue supergiants and collapse at the end of their nuclear burning lifetimes after exiting the main sequence.
Original languageEnglish
Pages (from-to)463–473
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date22 Feb 2023
Publication statusPublished - 1 May 2023


  • quasars: general
  • black hole physics
  • early universe
  • dark ages, reionization, first stars
  • galaxies: formation
  • galaxies: high-redshift
  • UKRI
  • STFC
  • ST/P000509/1

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