Luminosity versus rotation in a supermassive star

Thomas W. Baumgarte, Stuart L. Shapiro

Research output: Contribution to journalArticlepeer-review


We determine the effect of rotation on the luminosity of supermassive stars. We apply the Roche model to calculate analytically the emitted radiation from a uniformly rotating, radiation-dominated supermassive configuration. We find that the luminosity at maximum rotation, when mass at the equator orbits at the Kepler period, is reduced by ∼36% below the usual Eddington luminosity from a corresponding nonrotating star. A supermassive star is believed to evolve in a quasi-stationary manner along such a maximally rotating "mass-shedding" sequence before reaching the point of dynamical instability; hence this reduced luminosity determines the evolutionary timescale. Our result therefore implies that the lifetime of a supermassive star prior to dynamical collapse is ∼36% longer than the value typically estimated by employing the usual Eddington luminosity.

Original languageEnglish (US)
Pages (from-to)937-940
Number of pages4
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Dec 1 1999


  • Stars: formation
  • Stars: interiors stars: rotation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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