Constraining the orbital history of the Magellanic Clouds: a new bound scenario suggested by the tidal origin of the Magellanic Stream
Constraining the orbital history of the Magellanic Clouds: a new bound scenario suggested by the tidal origin of the Magellanic Stream
复制标题
限制麦哲伦云的轨道历史：麦哲伦流的潮汐起源提出的新的束缚场景
DOI：
10.1111/j.1365-2966.2011.18289.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
K. Bekki
中科院分区：
文献类型：
--
作者：
Jonathan D. Diaz;K. Bekki
传统上，束缚轨道被分配给大麦哲伦星云和小麦哲伦星云（分别为 LMC 和 SMC），以便为麦哲伦星流 (MS) 及其前臂 (LA) 提供形成场景，这两个重要的中性氢 (HI) 特征与 LMC 和 SMC 连接。然而，哈勃太空望远镜（HST）对 LMC 和 SMC 自行的测量对束缚轨道的合理性提出了挑战，导致 MS 的起源重新成为一个有争议的问题。我们提出了一种新的潮汐模型，其中类似于分叉 MS 和拉长 LA 的结构能够在与 HST 自行运动一致的束缚轨道中形成。尽管 LMC 和 SMC 分别与银河系结合超过 5 吉里，但在我们的模型中直到最近才保持彼此结合。我们发现，在 LMC 和 SMC 最近的动态耦合过程中，MS 和 LA 是由于 LMC 主导的潮汐剥离而形成的。我们的轨道模型取决于我们的假设，即银河系具有恒定的圆周速度 V cir = 250 km s -1 至 160 kpc，这意味着存在一个不完全是巨大的等温晕。
Bound orbits have traditionally been assigned to the Large and Small Magellanic Clouds (LMC and SMC, respectively) in order to provide a formation scenario for the Magellanic Stream (MS) and its Leading Arm (LA), two prominent neutral hydrogen (HI) features connected to the LMC and SMC. However, Hubble Space Telescope (HST) measurements of the proper motions of the LMC and SMC have challenged the plausibility of bound orbits, causing the origin of the MS to re-emerge as a contested issue. We present a new tidal model in which structures resembling the bifurcated MS and elongated LA are able to form in a bound orbit consistent with the HST proper motions. The LMC and SMC have remained bound to each other only recently in our model despite being separately bound to the Milky Way for more than 5 Gyr. We find that the MS and LA are able to form as a consequence of LMC-dominated tidal stripping during the recent dynamical coupling of the LMC and SMC. Our orbital model depends on our assumption that the Milky Way has a constant circular velocity of V cir = 250 km s −1 up to 160 kpc, which implies a massive isothermal halo that is not completely