New clues on outburst mechanisms and improved spectroscopic elements of the black hole binary V4641 Sagittarii
New clues on outburst mechanisms and improved spectroscopic elements of the black hole binary V4641 Sagittarii
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DOI：
10.1111/j.1365-2966.2005.09483.x
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发表时间：
2005-08
影响因子：
4.8
通讯作者：
C. Lindstrøm;J. Griffin;László L. Kiss;Makoto Uemura;Makoto Uemura;A. Derekas;A. Derekas;Sz. Mészáros;P. Székely
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文献类型：
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作者：
C. Lindstrøm;J. Griffin;László L. Kiss;Makoto Uemura;Makoto Uemura;A. Derekas;A. Derekas;Sz. Mészáros;P. Székely
我们目前的光谱观测的黑洞双星V4641人马座，2004年7月4日和2005年3月28日之间获得的，其中包括轻微的爆发的星星在2004年7月初和宁静的变化分散在6个月的19个夜晚。在爆发期间，这颗星星的峰值比平时亮了大约3等，我们的光谱主要是由宽的氢、氦和铁发射线组成。最早的光谱显示了天鹅座P的轮廓，在几个小时内消失，表明物质喷射的快速变化。Hα线有多个分量，其中之一是超过5000 km s-1的宽蓝移机翼。在同时观察到的10分钟光度耀斑，等效宽度的Ha线暂时减少，这意味着它是一个耀斑的连续。整体光谱外观与1999年9月活跃阶段观察到的相似，这表明类似的质量喷射过程与两次爆发有关。在静止时，光谱是早期次级星星的光谱，显示出它围绕主星的轨道运动。通过测量互相关径向速度，我们给出了一组改进的光谱元件。而我们测量的速度幅值（K2 = 211.3 ± 1.0km s-1）与Orosz等人测量的速度幅值相同，误差在误差范围内，我们的质心速度（y = 72.7 ± 3.3 km s-1）与以前公布的值（107.4 ± 2.9 km s-1）有很大的不同。然而，我们发现的证据表明，这种差异是由以前研究中数据简化的系统误差引起的，而不是由不可见的第三分量的引力效应引起的。
We present spectroscopic observations of the black hole binary V4641 Sagittarii, obtained between 2004 July 4 and 2005 March 28, which cover the minor outburst of the star in early 2004 July and quiescence variations on 19 nights scattered over six months. During the outburst, the star peaked approximately 3 mag brighter than usual, and our spectra were dominated by broad hydrogen, helium and iron emission lines. The very first spectra showed P Cygni profiles, which disappeared within a few hours, indicating rapid changes in matter ejection. The Hα line had multiple components, one being a broad blueshifted wing exceeding 5000 km s -1 . During a simultaneously observed 10-min photometric flare up, the equivalent width of the Ha line temporarily decreased, implying that it was a flare of the continuum. The overall spectral appearance was similar to that observed in the 1999 September active phase, which suggests that similar mass-ejection processes were associated with both eruptions. In quiescence, the spectra were those of the early-type secondary star showing its orbital motion around the primary. By measuring cross-correlation radial velocities, we give an improved set of spectroscopic elements. Whereas we measure the same velocity amplitude (K 2 = 211.3 ± 1.0 km s -1 ), within errors, as Orosz et al., our centre-of-mass velocity (y = 72.7 ± 3.3 km s -1 ) differs significantly from the previously published value (107.4 ± 2.9 km s -1 ). However, we find evidence that the difference is caused by a systematic error in data reduction in the previous study, rather than by gravitational effects of an invisible third component.