More on the structure of tidal tails
More on the structure of tidal tails
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更多关于潮汐尾结构的信息
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
D. Heggie
中科院分区：
文献类型：
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作者：
A. Kuepper;R. Lane;D. Heggie
我们研究逃离星团的恒星的周转运动。使用条纹线，我们可视化逃逸恒星的路径，并展示周转运动如何导致在围绕星系的圆形和偏心轨道上移动的星团潮汐尾密度过高和过低。此外，我们还研究了星团质量对潮汐尾部的影响，结果表明，当包含星团质量的扰动效应时，潮汐尾部的结构会更好地匹配。通过根据 N 体计算结果调整条纹线，我们可以准确、快速地重现所有观测到的子结构，特别是模拟中经常发现的条纹特征，这些特征在观测中可能被解释为多个潮汐尾。因此，我们可以排除潮汐冲击是此类下部结构的起源。最后，从调整后的条纹线参数中我们可以验证，对于我们研究的星团来说，逃逸主要发生在星团的潮汐半径处，由 xL = (GM/( 2 ∂ 2 �/∂R 2 )) 1/3 给出。然而，我们发现还有另一个限制半径，即“边缘”半径，它给出了恒星在围绕星系的一个星团轨道期间可以逃离的最小半径。对于偏心星团轨道，边缘半径随着轨道偏心率的增加而缩小（对于固定的远心距离），但总是显着大于各自的银河系潮汐半径。事实上，我们研究的星团的边缘半径（它们是延伸的且潮汐填充的）与它们的（拟合的）King 半径非常吻合，这可能表明这两个量之间存在基本联系。
We investigate the epicyclic motion of stars escaping from star clusters. Using streaklines, we visualise the path of escaping stars and show how epicyclic motion leads to over- and underdensities in tidal tails of star clusters moving on circular and eccentric orbits about a galaxy. Additionally, we investigate the effect of the cluster mass on the tidal tails, by showing that their structure is better matched when the perturbing effect of the cluster mass is included. By adjusting streaklines to results of N-body computations we can accurately and quickly reproduce all observed substructure, especially the streaky features often found in simulations which may be interpreted in observations as multiple tidal tails. Hence, we can rule out tidal shocks as the origin of such substructures. Finally, from the adjusted streakline parameters we can verify that for the star clusters we studied escape mainly happens from the tidal radius of the cluster, given by xL = (GM/( 2 ∂ 2 �/∂R 2 )) 1/3 . We find, however, that there is another limiting radius, the “edge” radius, which gives the smallest radius from which a star can escape during one cluster orbit about the galaxy. For eccentric cluster orbits the edge radius shrinks with increasing orbital eccentricity (for fixed apocentric distance) but is always significantly larger than the respective perigalactic tidal radius. In fact, the edge radii of the clusters we investigated, which are extended and tidally filling, agree well with their (fitted) King radii, which may indicate a fundamental connection between these two quantities.