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arXiv · 0803.0605

HD148937: a multiwavelength study of the third Galactic member of the Of?p class

Y. Naze·N. R. Walborn·G. Rauw·F. Martins·A. M. T. Pollock·H. E. Bond
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Abstract

Three Galactic O-type stars belong to the rare class of Of?p objects: HD108, HD191612, and HD148937. The first two stars show a wealth of phenomena, including magnetic fields and 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, HD148937. Spectroscopic monitoring has revealed low-level variability in the Balmer and HeII4686 lines, but constancy at HeI and CIII4650. The Ha line exhibits profile variations at a possible periodicity of ~7d. Model atmosphere fits yield T_{eff}=41000+-2000K, log(g)=4.0+-0.1, Mdot_{sph}<~ 10^{-7}Msol/yr and a surabondance of nitrogen by a factor of four. At X-ray wavelengths, HD148937 resembles HD108 and HD191612 in having a thermal spectrum dominated by a relatively cool component (kT=0.2keV), broad lines (>1700km/s), and an order-of-magnitude overluminosity compared to normal O stars (log [L_X^unabs/L_BOL] ~ -6).

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Y. Naze, N. R. Walborn, G. Rauw, F. Martins, A. M. T. Pollock, H. E. Bond. 2008-03-05. HD148937: a multiwavelength study of the third Galactic member of the Of?p class. https://doi.org/10.1088/0004-6256%2F135%2F5%2F1946

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