CIR Modulation of the X-ray Flux from the O7.5 III(n)((f)) Star ξ Persei?

D. Massa, L. Oskinova, A.W. Fullerton, R.K. Prinja, D.A. Bohlender, N.D. Morrison, M. Blake and W. Pych

Abstract: We analyze a 162 ks HETG Chandra observation of the O7.5 III(n)((f)) star ξ Per, together with contemporaneous Hα observations. The X-ray spectrum of this star is similar to other single O stars, and not pathological in any way. Its UV wind lines are known to display cyclical time variability, with a period of 2.086 days, which is thought to be associated with co-rotating interaction regions (CIRs). We examine the Chandra and Hα data for variability on this time scale. We find that the X-rays vary by 15% over the course of the observations and that this variability is out of phase with variable absorption on the blue wing of the Hα profiles (assumed to be a surrogate for the UV absorption associated with CIRs). While not conclusive, both sets of data are consistent with models where the CIRs are either a source of X-rays or modulate them.

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Paper in NASA ADS

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