感受拉力，自然银河加速计的研究。II：Palomar 5球状星团的精细恒星流的运动学和质量
Feeling the pull, a study of natural Galactic accelerometers. II: kinematics and mass of the delicate stellar stream of the Palomar 5 globular cluster
摘要：
我们提出了两个光谱调查的Palomar 5球状星团的潮汐恒星流，进行了VLT/FLAMES和AAT/AAOmega仪器。我们使用这些数据结合光度数据在本系列中的前一份贡献中提出的调查恒星属于帕洛玛5恒星流的概率进行分类。我们发现，高概率的候选人只发现在一个非常狭窄的空间间隔周围的轨迹流的天空。PanSTARRS RR天琴座恒星在这一区域的分布也是类似的。这一恒星流没有明显的“扇形”，证实了帕洛玛5号并没有遵循混沌轨道。以前的研究发现，帕洛玛5是在很大程度上缺乏低质量的恒星，我们表明，这也是真实的恒星星族沿拖臂到$6°$。在这一区域内，包含了73%的被探测到的恒星，其星群在统计上与核心相同，这意味着低质量恒星的抛射发生在星流形成之前。我们还提出了一个更新的结构模型，适合绑定的残余物，产生的总质量为$4297\pm98 {\rm\,M_\odot}$和潮汐半径$0.145\pm0.009$千秒差距。我们估计所观察到的系统，包括流的质量是$12200\pm400 {\rm\,M_\odot}$，和初始质量已$\sim47000\pm1500 {\rm\,M_\odot}$。这些观测约束将在我们的下一个研究中详细模拟系统的动力学。
英文摘要：
We present two spectroscopic surveys of the tidal stellar stream of the Palomar 5 globular cluster, undertaken with the VLT/FLAMES and AAT/AAOmega instruments. We use these data in conjunction with photometric data presented in the previous contribution in this series to classify the survey stars in terms of their probability of belonging to the Palomar 5 stellar stream. We find that high-probability candidates are only found in a very narrow spatial interval surrounding the locus of the stream on the sky. PanSTARRS RRLyrae stars in this region of sky are also distributed in a similar manner. The absence of significant "fanning" of this stellar stream confirms that Palomar 5 does not follow a chaotic orbit. Previous studies have found that Palomar 5 is largely devoid of low-mass stars, and we show that this is true also of the stellar populations along the trailing arm out to $6°$. Within this region, which contains 73\% of the detected stars, the population is statistically identical to the core, implying that the ejection of the low-mass stars occurred before the formation of the stream. We also present an updated structural model fit to the bound remnant, which yields a total mass of $4297\pm98 {\rm\,M_\odot}$ and a tidal radius $0.145\pm0.009$ kpc. We estimate the mass of the observed system including the stream to be $12200\pm400 {\rm\,M_\odot}$, and the initial mass to have been $\sim47000\pm1500 {\rm\,M_\odot}$. These observational constraints will be employed in our next study to model the dynamics of the system in detail.
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