论文标题
麦哲伦混乱：金属和动作
Magellanic Mayhem: Metallicities and Motions
论文作者
论文摘要
我们从$ Gaia $ Mission的数据发行2中组装了一个麦哲伦云红色巨头的目录，并利用机器学习方法获得了它们的光度金属估计。通过这样做，我们能够立即对整个麦哲伦系统进行化学绘制。我们的高分辨率地图显示了大量的下结构，其中大麦芽云（LMC）杆和螺旋臂很明显。我们在LMC碟片的南部揭示了一个奇怪的螺旋状特征，它拥有相对富含金属的巨人，并且可能与小型麦哲伦云（SMC）的历史相遇副产品。将LMC建模为倾斜的薄圆盘，我们找到了$ -0.048 \ pm 0.001 $ dex/kpc/kpc的浅金属梯度，从矮人的中心开始到$ \ sim 12^{\ circ} $。我们看到的证据表明，小麦芽云正在破坏，其外ISO密度轮廓显示出潮汐剥离的S形症状。在研究SMC巨头的适当动作时，我们观察到其中的一个人被猛烈地拖到更大的云中。受干扰的恒星主要位于SMC的前面，我们认为它们是矮人的潮汐尾巴，在其运动中落后，并受到LMC的严重破坏。我们发现麦哲伦桥区的金属性结构很复杂，有证据表明该恒星种群中的复合性质，包括LMC和SMC碎片。
We assemble a catalogue of Magellanic Cloud red giants from Data Release 2 of the $Gaia$ mission and, utilising machine learning methods, obtain photometric metallicity estimates for them. In doing so, we are able to chemically map the entirety of the Magellanic System at once. Our high resolution maps reveal a plethora of substructure, with the Large Magellanic Cloud (LMC) bar and spiral arm being readily apparent. We uncover a curious spiral-like feature in the southern portion of the LMC disc, hosting relatively metal-rich giants and likely a by-product of historic encounter with the Small Magellanic Cloud (SMC). Modelling the LMC as an inclined thin disc, we find a shallow metallicity gradient of $-0.048 \pm 0.001$ dex/kpc out to $\sim 12^{\circ}$ from the centre of the dwarf. We see evidence that the Small Magellanic Cloud is disrupting, with its outer iso-density contours displaying the S-shape symptomatic of tidal stripping. On studying the proper motions of the SMC giants, we observe a population of them being violently dragged towards the larger Cloud. The perturbed stars predominately lie in front of the SMC, and we interpret that they exist as a tidal tail of the dwarf, trailing in its motion and undergoing severe disruption from the LMC. We find the metallicity structure in the Magellanic Bridge region to be complex, with evidence for a composite nature in this stellar population, consisting of both LMC and SMC debris.
