论文标题
VMC调查-XLVIII。经典的头孢虫揭示了LMC的3D几何形状
The VMC Survey -- XLVIII. Classical Cepheids unveil the 3D geometry of the LMC
论文作者
论文摘要
我们采用了{\ it Vista近红外$ yjk_ \ mathrm {s} $调查麦芽岩系统}(vmc),分析$ y,\,j,j,j,j \,k_ \ mathrm {s} $ copheid sstars(dceps)的$ y mathrm {s}我们的样本由4408个对象组成,占OGLE \,IV和{\ IT GAIA} \,DR2 DCEPS的组合列表的97%。我们确定了各种时期luminitos($ pl $)和基本(F)和第一张开(1o)脉动器的时期$ pw $关系。我们首次在这些关系中发现了1o dceps $ p $ = 0.58 d。我们以$ \ sim $ 1 kpc的精度得出了LMC中DCEP的相对个性距离,计算了节点线的位置角度和星系的倾斜度:$θ$ = 145.6 $ \ pm $ 1.0°$ = 25.7 $ \ pm $ 0.4 $ $ 0.4°$ 0.4度。条形和光盘在不同的视角下看到。我们计算了脉动器的年龄,发现了持续$ \ sim $ 40 Myr的两个主要剧集,发生在93和159 Myr以前。 LMC可能是由于其过去与SMC的相互作用而导致的,其结构相当可观:将栏分为两个不同的部分,即东部和西部,彼此相互偏离超过1 kpc。螺旋臂显示了类似的行为。 LMC光盘显示为“爆发”且厚度,圆盘尺度高度为$ h \ sim 0.97 $ kpc。可以通过与银河系的强烈潮汐相互作用和/或现在被干扰的LMC卫星合并事件来解释此功能。
We employed the {\it VISTA near-infrared $YJK_\mathrm{s}$ survey of the Magellanic System} (VMC), to analyse the $Y,\,J,\,K_\mathrm{s}$ light curves of $δ$ Cepheid stars (DCEPs) in the Large Magellanic Cloud (LMC). Our sample consists of 4408 objects accounting for 97 per cent of the combined list of OGLE\,IV and {\it Gaia}\,DR2 DCEPs. We determined a variety of period-luminosity ($PL$) and period-Wesenheit $PW$ relationships for Fundamental (F) and First Overtone (1O) pulsators. We discovered for the first time a break in these relationships for 1O DCEPs at $P$=0.58 d. We derived relative individual distances for DCEPs in the LMC with a precision of $\sim$1 kpc, calculating the position angle of the line of nodes and inclination of the galaxy: $θ$=145.6$\pm$1.0 deg and $i$=25.7$\pm$0.4 deg. The bar and the disc are seen under different viewing angles. We calculated the ages of the pulsators, finding two main episodes of DCEP formation lasting $\sim$40 Myr which happened 93 and 159 Myr ago. Likely as a result of its past interactions with the SMC, the LMC shows a non-planar distribution, with considerable structuring: the bar is divided into two distinct portions, the eastern and the western displaced by more than 1 kpc from each other. Similar behaviour is shown by the spiral arms. The LMC disc appears "flared" and thick, with a disc scale height of $h\sim 0.97$ kpc. This feature can be explained by strong tidal interactions with the Milky Way and/or the Small Magellanic Cloud or past merging events with now disrupted LMC satellites.