论文标题
VMC调查 - XXXIX：使用近红外横带的小麦芽云中映射金属性趋势
The VMC survey -- XXXIX: Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands
论文作者
论文摘要
我们衍生出高空间分辨率的金属图，覆盖了$ \ sim $ 42度$^2 $在小型麦哲伦云（SMC）中，以试图了解其金属分布和梯度至$ \ sim $ 4 $^{\ circ} $。使用对麦哲伦云的近红外远景调查，与以前的研究相比，我们的数据涵盖了更大的区域。我们在空间上不同的$ y，（y-k _ {\ rm s}）$ colour-颜色图中识别红色巨型分支（RGB）星。在我们选定的任何子区域中，RGB斜率都用作平均金属性的指标，基于使用光谱数据校准金属性。 SMC上的金属分布是单峰的，可以通过高斯分布拟合，高峰为[Fe/H] = $ - $ 0.97 DEX（$σ$ [Fe/H] = 0.05 DEX）。我们找到了从银河中心到2 $^{\ circ} $ - 2.5 $^{\ circ} $的浅金属梯度（$ -0.031 \ pm 0.005 $ 0.005 $ dex deg $^{ - 1} $）的证据我们发现SMC的金属性梯度是径向不对称的。它是向东倾斜的，而不是向西，暗示了空间金属分布的混合和/或变形（在内部3 $^{\ circ} $中，可能是由于麦哲伦云之间的潮汐相互作用而引起的。
We have derived high spatial resolution metallicity maps covering $\sim$42 deg$^2$ across the Small Magellanic Cloud (SMC) in an attempt to understand its metallicity distribution and gradients up to a radius of $\sim$ 4$^{\circ}$. Using the near-infrared VISTA Survey of the Magellanic Clouds, our data cover a thrice larger area compared with previous studies. We identify red giant branch (RGB) stars in spatially distinct $Y, (Y-K_{\rm s})$ colour--magnitude diagrams. In any of our selected subregions, the RGB slope is used as an indicator of the average metallicity, based on calibration to metallicity using spectroscopic data. The metallicity distribution across the SMC is unimodal and can be fitted by a Gaussian distribution with a peak at [Fe/H] = $-$0.97 dex ($σ$[Fe/H] = 0.05 dex). We find evidence of a shallow gradient in metallicity ($-0.031 \pm 0.005$ dex deg$^{-1}$) from the galactic centre to radii of 2$^{\circ}$--2.5$^{\circ}$, followed by a flat metallicity trend from $\sim$ 3.5$^{\circ}$ to 4$^{\circ}$. We find that the SMC's metallicity gradient is radially asymmetric. It is flatter towards the East than to the West, hinting at mixing and/or distortion of the spatial metallicity distribution (within the inner 3$^{\circ}$), presumably caused by tidal interactions between the Magellanic Clouds.
