The Interacting Early-Type Binary BD +40°4220 (V729 Cyg): Modeling the Colliding Winds Region
The Interacting Early-Type Binary BD +40°4220 (V729 Cyg): Modeling the Colliding Winds Region
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DOI：
10.1086/307185
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发表时间：
1999-05
期刊：
影响因子：
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通讯作者：
G. Rauw;J. Vreux;B. Bohannan
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文献类型：
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作者：
G. Rauw;J. Vreux;B. Bohannan
我们对神秘的早期双星BD+40°4220的一系列光谱观测进行了分析。从吸收谱线的径向速度导出了一个新的轨道解。我们确认了这颗次级恒星的质量是非常高的。这两个组分的吸收线都表现出锁相的轮廓变化，其中一些次级吸收线在ϕ=0.20和ϕ=0.55之间进入发射。对He IIλ4686发射谱线的廓线变率进行了详细的研究，发现该谱线的变率模式非常稳定。我们发现，He IIλ4686发射的一部分是在恒星之间的风相互作用区产生的。BD+40°4220可见光光谱中的大多数发射线都显示出变化，这让人想起在He IIλ4686线上观察到的变化，指向类似的起源。我们对碰撞风双星的发射线廓线进行了数值模拟，结果表明，在BD+40°4220观测到的变率的一个重要部分可以用碰撞风现象来解释。如果我们假设副星是一个演化的天体，很可能是某种Ofpe/Wn9过渡星，质量损失率约为5.5×10-6M☉yr-1，那么风相互作用区的性质就可以解释。最后，我们讨论了双星的基本参数，得出的结论是，质量传递一定在这个系统的演化中起到了至关重要的作用。
We present an analysis of an extensive set of spectroscopic observations of the mysterious early-type binary BD +40°4220. A new orbital solution is derived from the radial velocities of the absorption lines. We confirm that the secondary star is highly overluminous for its mass. The absorption lines of both components display phase-locked profile variations, with some of the secondary's lines going into emission between ϕ=0.20 and ϕ=0.55. A detailed investigation of the profile variability of the He II λ4686 emission line reveals that the pattern of variability of this line is very stable. We show that part of the He II λ4686 emission is produced in the wind interaction region between the stars. Most of the emission lines in the visual spectrum of BD +40°4220 display variations that are reminiscent of those observed on the He II λ4686 line, pointing toward a similar origin. We present numerical simulations of emission-line profiles in a colliding winds binary, showing that an important part of the variability observed in BD +40°4220 can be explained by a colliding winds phenomenon. The properties of the wind interaction region can be accounted for if we assume that the secondary star is an evolved object, most probably some kind of Ofpe/WN9 transition star, with a mass loss rate of ~5.5 × 10-6 M☉ yr-1. We finally discuss the fundamental parameters of the binary, concluding that mass transfer must have played a crucial role in the evolution of this system.