HD 148937: A multiwavelength study of the third galactic member of the of?p class

Yaël Nazé, Nolan R. Walborn, Gregor Rauw, Fabrice Martins, A. M.T. Pollock, Howard E. Bond

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37 Scopus citations


Three Galactic O-type stars belong to the rare class of Of?p objects: HD 108, HD 191612, and HD 148937. The first two stars show a wealth of phenomena, including strong X-ray emission, light variability, and dramatic periodic spectral variability. We present here the first detailed optical and X-ray study of the third Galactic Of?p star, HD 148937. Spectroscopic monitoring has revealed low-level variability in the Balmer and He II λ4686 lines, but constancy at He I and C III λ4650. The Hα line exhibits profile variations at a possible periodicity of 7 days. Model atmosphere fits yield T eff = 41000 2000 K, log(g) = 4.0 0.1, M yr -1, and an overabundance of nitrogen by a factor of 4. At X-ray wavelengths, HD 148937 resembles HD 108 and HD 191612 in having a thermal spectrum dominated by a relatively cool component (kT = 0.2 keV), broad lines (≥1700 km s-1), and an order-of-magnitude overluminosity compared to normal O stars (log[L unabs X/L BOL] -6).

Original languageEnglish (US)
Pages (from-to)1946-1957
Number of pages12
JournalAstronomical Journal
Issue number5
StatePublished - May 1 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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