arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1502.06603astro-ph.SRastro-ph.GA
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激变变星的银河系动能

The Galactic Kinematics of Cataclysmic Variables

T. Ak, S. Bilir, A. Özdönmez, F. Soydugan, E. Soydugan, C. Püsküllü, S. Ak, Z. Eker

摘要:

根据人口类型和轨道周期,使用最近更新的系统速度,自行和松弛计算的空间速度的CV的运动学特性进行了研究。通过剔除34个空间速度误差最大的系统,提高了所收集空间速度数据的可靠性。在精制样品中的216个CV显示出具有$53.70 \pm 7.41$ km s $^{-1}$的分散度,对应于$5.29 \pm 1.35$ Gyr的平均运动学年龄。人口类型的CV确定使用他们的银河系轨道参数。根据星群分析,在样本中发现了7个老薄盘、9个厚盘和1个晕CV,表明太阳邻域中94%的CV属于银河系的薄盘成分。平均运动学年龄$3.40 \pm 1.03$和$3.90 \pm 1.28$ Gyr分别为周期间隙以下和以上的非磁性薄圆盘CV。在间隙下方和上方的速度分散之间没有有意义的差异。非磁性薄盘系统的速度分散的以下和以上的间隙分别为$24.95 \pm 3.46$和$26.60 \pm 4.18$ km s $^{-1}$。这一结果不符合CV的标准形成和演化理论。CV组在不同轨道周期间隔的平均运动学年龄随轨道周期的缩短而增大。这与CV进化的标准理论是一致的。发现轨道周期变化率为$dP/dt=-1.62(\pm 0.15)\times 10^{-5}$秒/年$^{-1}$。

英文摘要:

Kinematical properties of CVs were investigated according to population types and orbital periods, using the space velocities computed from recently updated systemic velocities, proper motions and parallaxes. Reliability of collected space velocity data are refined by removing 34 systems with largest space velocity errors. The 216 CVs in the refined sample were shown to have a dispersion of $53.70 \pm 7.41$ km s$^{-1}$ corresponding to a mean kinematical age of $5.29 \pm 1.35$ Gyr. Population types of CVs were identified using their Galactic orbital parameters. According to the population analysis, seven old thin disc, nine thick disc and one halo CV were found in the sample, indicating that 94% of CVs in the Solar Neighbourhood belong to the thin-disc component of the Galaxy. Mean kinematical ages $3.40 \pm 1.03$ and $3.90 \pm 1.28$ Gyr are for the non-magnetic thin-disc CVs below and above the period gap, respectively. There is not a meaningful difference between the velocity dispersions below and above the gap. Velocity dispersions of the non-magnetic thin-disc systems below and above the gap are $24.95 \pm 3.46$ and $26.60 \pm 4.18$ km s$^{-1}$, respectively. This result is not in agreement with the standard formation and evolution theory of CVs. The mean kinematical ages of the CV groups in various orbital period intervals increase towards shorter orbital periods. This is in agreement with the standard theory for the evolution of CVs. Rate of orbital period change was found to be $dP/dt=-1.62(\pm 0.15)\times 10^{-5}$ sec yr$^{-1}$.

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