The XMM-Newton EPIC X-ray Light Curve Analysis of WR 6
R. Ignace, K.G. Gayley, W.-R. Hamann, D.P. Huenemoerder, L.M. Oskinova, A.M.T. Pollock, M. McFall
We obtained four pointings of over 100 ks each of the well-studied
Wolf-Rayet star WR 6 with the XMM-Newton satellite. With a first paper
emphasizing the results of spectral analysis, this follow-up highlights
the X-ray variability clearly detected in all four pointings. However,
phased light curves fail to confirm obvious cyclic behavior on the
well-established 3.766 d period widely found at longer wavelengths. The
data are of such quality that we were able to conduct a search for
"event clustering" in the arrival times of X-ray photons. However, we
fail to detect any such clustering. One possibility is that X-rays are
generated in a stationary shock structure. In this context we favor a
co-rotating interaction region (CIR) and present a phenomenological
model for X-rays from a CIR structure. We show that a CIR has the
potential to account simultaneously for the X-ray variability and
constraints provided by the spectral analysis. Ultimately, the viability
of the CIR model will require both intermittent long-term X-ray
monitoring of WR 6 and better physical models of CIR X-ray production at
large radii in stellar winds.
Fetch Pdf-File (ignace-2013-wr6.pdf, 1MB)