论文标题

Viscacha调查-IV。 8D中的SMC West Halo

The VISCACHA survey -- IV. The SMC West Halo in 8D

论文作者

Dias, B., Parisi, M. C., Angelo, M., Maia, F., Oliveira, R. A. P., Souza, S. O., Kerber, L. O., Santos Jr., J. F. C., Pérez-Villegas, A., Sanmartim, D., Quint, B., Fraga, L., Barbuy, B., Bica, E., Santrich, O. J. Katime, Hernandez-Jimenez, J. A., Geisler, D., Minniti, D., De Bórtoli, B. J., Bassino, L. P., Rocha, J. P.

论文摘要

小麦哲伦云(SMC)的结构非常复杂,尤其是在与大型麦哲伦云(LMC)相互作用的外围。已经积累了大量的观察性证据,揭示了由气体,恒星和星团组成的潮汐尾巴和桥梁。然而,SMC郊区的完整图片直到最近才开始出现6D相位地图以及使用Star Clusters作为示踪剂的年龄和金属性。在这项工作中,我们继续分析SMC的另一个外部区域,即所谓的West Halo,并将其与先前分析的Northern Bridge相结合。我们使用这两种结构来定义桥梁和反桥的尾巴和领先的潮汐尾巴。这两个结构大致沿SMC-LMC方向彼此移开。西光环在SMC内部区域周围形成一个环,该戒指沿着北桥的背景塑造,塑造了反桥的扩展层。在距SMC中心大于8 kpc的距离处发现了四个旧的桥梁簇,这与大约150mryr的麦哲伦桥成立时,与最接近7.5 kpc的SMC-LMC一致;这表明,麦哲伦桥不仅是由拉气而形成的,但它在形成过程中也从SMC中取下了较老的恒星。我们还使用天空上的投影距离发现了年龄和金属性径向梯度,当我们使用真正的3D距离时,它们消失了。

The structure of the Small Magellanic Cloud (SMC) is very complex, in particular in the periphery that suffers more from the interactions with the Large Magellanic Cloud (LMC). A wealth of observational evidence has been accumulated revealing tidal tails and bridges made up of gas, stars and star clusters. Nevertheless, a full picture of the SMC outskirts is only recently starting to emerge with a 6D phase-space map plus age and metallicity using star clusters as tracers. In this work, we continue our analysis of another outer region of the SMC, the so-called West Halo, and combined it with the previously analysed Northern Bridge. We use both structures to define the Bridge and Counter-bridge trailing and leading tidal tails. These two structures are moving away from each other, roughly in the SMC-LMC direction. The West Halo form a ring around the SMC inner regions that goes up to the background of the Northern Bridge shaping an extended layer of the Counter-bridge. Four old Bridge clusters were identified at distances larger than 8 kpc from the SMC centre moving towards the LMC, which is consistent with the SMC-LMC closest distance of 7.5 kpc when the Magellanic Bridge was formed about 150Myr ago; this shows that the Magellanic Bridge was not formed only by pulled gas, but it also removed older stars from the SMC during its formation. We also found age and metallicity radial gradients using projected distances on sky, which are vanished when we use the real 3D distances.

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