Space Science Reviews

, Volume 66, Issue 1–4, pp 69–73 | Cite as

The population of massive stars in R136 from HST/FOC UV observations

  • Antonella Nota
  • Guido De Marchi
  • Claus Leitherer
  • Roberto Ragazzoni
  • Cesare Barbieri
Number and Distribution of Massive Stars


New ultraviolet (λ≃1300 A, λ≃3400 A),HST FOC observations have been used to derive the UV color-magnitude diagram (CMD) of R136, with the main scientific goal of studying the upper end of the stellar mass function at ultraviolet wavelengths where the color degeneracy encountered in visual CMDs is less severe. The CMD has been compared to a set of theoretical isochrones, which have been computed using the latest generation of evolutionary models and model atmospheres for early type stars. Wolf-Rayet stars are included. Comparison of theTheoretical andobserved CMD suggests that there are no stars brighter than M130≃−11. We use the observed main sequence turn-off and the known spectroscopic properties of the stellar population to derive constraints on the most probable age of R136. The presence of WNL stars and the lack of red supergiants suggests a most likely age of 3±1 Myr. A theoretical isochrone of 3±1 Myr is consistent with the observed stellar content of R136 if the most massive stars have initial masses around ≃50 M.

Key words

massive stars IMF clusters 


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Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Antonella Nota
    • 1
  • Guido De Marchi
    • 1
  • Claus Leitherer
    • 1
  • Roberto Ragazzoni
    • 2
  • Cesare Barbieri
    • 3
  1. 1.Space Telescope Science InstituteBaltimoreUSA
  2. 2.Osservatorio Astronomico di PadovaItaly
  3. 3.Dipartimento di AstronomiaUniversita' di PadovaItaly

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