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Towards an understanding of the Of?p star HD191612: Phase-resolved multiwavelength observations

Yael Naze·Gregor Rauw·A. M. T. Pollock·Nolan R. Walborn·Ian D. Howarth
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Abstract

We present the analysis of phase-resolved X-ray and optical observations of the peculiar hot star HD191612 (Of?p). This star is known to display line-profile variations that are recurrent with a period of 538d and its spectrum was found to present the signature of a magnetic field. In the X-rays, it is slightly overluminous compared to the canonical L_X/L_BOL relation and appears brighter when the optical lines are strongest. Our XMM-Newton observations further reveal that the X-ray spectrum of \hd exhibits rather broad lines and is dominated by a `cool' (0.2-0.6 keV) thermal component, two characteristics at odds with the proposed magnetic rotator model. We also report for the first time the low-level variability of the metallic (abs/em) lines and HeII absorptions that appear to be associated with radial-velocity shifts. Finally, we compare our results with observations of the early-type stars and discuss several possible scenarios.

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Yael Naze, Gregor Rauw, A. M. T. Pollock, Nolan R. Walborn, Ian D. Howarth. 2006-11-07. Towards an understanding of the Of?p star HD191612: Phase-resolved multiwavelength observations. https://doi.org/10.1111/j.1365-2966.2006.11270.x

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