Theoretical modeling of GHRS observations of the of/WN-type star R136a5

Alex De Koter, Ivan Hubeny, Sara R. Heap, Thierry Lanz

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Abstract

We present a theoretical analysis of the HST GHRS spectrum of R136a5, an O3f/WN star in the R136a cluster in 30 Doradus. Using non-LTE extended and expanding model atmospheres, we find a surprisingly high mass-loss rate Ṁ = 1.8 ± 0.5 × 10-5 M yr-1 and an effective temperature Teff = 42.5 ± 2.5 kK. With the observed visual magnitude, this implies a radius R* = 17 ± 2 R and a luminosity L = 8.5 ± 1 × 105 L. We discuss possible sources of the uncertainties in the derived stellar parameters and conclude that the effective temperature may be underestimated; however, if so, the value of the mass-loss rate would not be affected.

Original languageEnglish (US)
Pages (from-to)L71-L74
JournalAstrophysical Journal
Volume435
Issue number1 PART 2
StatePublished - Nov 1 1994

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Keywords

  • Stars: atmospheres
  • Stars: early-type
  • Stars: individual (R136a5, Melnick 42)
  • Stars: mass-loss
  • Ultraviolet: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

De Koter, A., Hubeny, I., Heap, S. R., & Lanz, T. (1994). Theoretical modeling of GHRS observations of the of/WN-type star R136a5. Astrophysical Journal, 435(1 PART 2), L71-L74.