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arXiv 1902.00447astro-ph.GAastro-ph.SR
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用盖亚DR2揭示的球状星团FSR1758的逆行轨道

The retrograde orbit of the globular cluster FSR1758 revealed with Gaia DR2

Jeffrey D. Simpson

摘要:

我们报告了最近发现的球状星团FSR 1758的第一次径向速度测量。从Gaia DR 2中报道的Gaia径向速度摄谱仪的两个成员星的径向速度,我们发现FSR 1758的径向速度为$227\pm1$ km/s。我们还发现了潜在的潮外星从星团中消失在周围1~deg。结合盖亚自行和测光距离估计,这表明FSR 1758是在一个非常逆行的径向轨道上,近心点为$3.8_{-0.9}^{+0.9}$ kpc,远心点为$16_{-5}^{+8}$ kpc,离心率为$0.62_{-0.04}^{+0.05}$。虽然它目前在银河系中心距离$3.8_{-0.9}^{+0.9}$千秒差距-在凸起的边缘-它是来自光环的入侵者。我们调查是否报告的“晕”FSR 1758周围的恒星有关的集群,并发现这些恒星中的大多数可能是前景矮星。我们的结论是FSR 1758不是一个矮星系,而是一个球状星团。

英文摘要:

We report the first radial velocity measurements of the recently identified globular cluster FSR1758. From the two member stars with radial velocities from the Gaia Radial Velocity Spectrograph reported in Gaia DR2, we find FSR1758 has a radial velocity of $227\pm1$ km/s. We also find potential extra-tidal star lost from the cluster in the surrounding 1~deg. Combined with Gaia proper motions and photometric distance estimates, this shows that FSR1758 is on a very retrograde, radial orbit with an pericentre of $3.8_{-0.9}^{+0.9}$ kpc, an apocentre of $16_{-5}^{+8}$ kpc, and eccentricity of $0.62_{-0.04}^{+0.05}$. Although it is currently at a Galactocentric distance of $3.8_{-0.9}^{+0.9}$ kpc --- at the edge of the bulge --- it is an intruder from the halo. We investigate whether a reported `halo' of stars around FSR1758 is related to the cluster, and find that most of these stars are likely foreground dwarf stars. We conclude that FSR1758 is not a dwarf galaxy, but rather a globular cluster.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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