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arXiv 1004.4893astro-ph.SR
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Wolf-Rayet星WR1（HD 4004）风的大尺度周期变率

Large-Scale Periodic Variability of the Wind of the Wolf-Rayet Star WR1 (HD 4004)

André-Nicolas Chené, Nicole St-Louis

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19 pages, 13 figures, 1 table, accepted in ApJ
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摘要：

我们提出了一个密集的光度和光谱监测活动的WN 4沃尔夫-拉叶（WR）星WR 1 = HD 4004的结果。我们的宽带V测光覆盖的时间跨度为91天，显示的变化与P=16.9 $^{+0.6}_{-0.3}$天。我们的光谱数据中也发现了相同的周期。光变曲线是非正弦曲线，其形状随时间逐渐变化。然而，光度变化在几个周期内仍然是一致的，我们估计光变曲线的相干时间尺度为60天。光谱显示出大规模的线轮廓的变化，这可以被解释为多余的发射峰移动从一侧的配置文件的其他几天的时间尺度。虽然我们不能明确地排除不太可能的可能性，WR 1是一个二进制，我们建议，我们已经发现的变化的性质强烈表明，这是由于存在于风的WR星的大尺度结构，最有可能的同向旋转相互作用区（CIR），这是预测出现在固有的不稳定的辐射驱动风时，他们在他们的基地扰动。我们还认为，在WR 6，WR 134和WR 137中观察到的变异性是相同的性质。最后，假设CIR的周期与自转周期有关，我们估计了已经进行了充分监测的四颗恒星的自转速率，即WR 1、WR 6、WR 134和WR 137的v $_{rot}$ =6.5、40、70和275 km/s。

英文摘要：

We present the results of an intensive photometric and spectroscopic monitoring campaign of the WN4 Wolf-Rayet (WR) star WR1=HD4004. Our broadband V photometry covering a timespan of 91 days shows variability with a period of P=16.9$^{+0.6}_{-0.3}$ days. The same period is also found in our spectral data. The light-curve is non-sinusoidal with hints of a gradual change in its shape as a function of time. The photometric variations nevertheless remain coherent over several cycles and we estimate that the coherence timescale of the light-curve is of the order of 60 days. The spectroscopy shows large-scale line-profile variability which can be interpreted as excess emission peaks moving from one side of the profile to the other on a timescale of several days. Although we cannot unequivocally exclude the unlikely possibility that WR1 is a binary, we propose that the nature of the variability we have found strongly suggests that it is due to the presence in the wind of the WR star of large-scale structures, most likely Co-rotating Interaction Regions (CIRs), which are predicted to arise in inherently unstable radiatively driven winds when they are perturbed at their base. We also suggest that variability observed in WR6, WR134 and WR137 is of the same nature. Finally, assuming that the period of CIRs is related to the rotational period, we estimate the rotation rate of the four stars for which sufficient monitoring has been carried out; i.e. v$_{rot}$=6.5, 40, 70 and 275 km/s for WR1, WR6, WR134 and WR137, respectively.

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