论文标题
年轻SMC区域NGC 602中的顺序星形形成：来自阿尔玛的见解
Sequential Star Formation in the Young SMC Region NGC 602: Insights from ALMA
论文作者
论文摘要
NGC 602是小型麦哲伦云的“机翼”中的年轻，低金属的星团。我们通过分析高分辨率（$ \ sim $ 0.4 pc）Atacama大毫米/毫米阵列观测到相关的$ \ textrm {H} \ ScriptStyle \ Mathrm {II II} $ necroy n90。我们确定了通过CO发射追踪的110个分子团（$ r <$ r <$ 0.8 PC），并研究了团块与相关的年轻恒星对象（YSOS）和预序列序列（PMS）恒星之间的关系。这些团块具有较高的病毒参数（典型的$α_ {\ rm {vir}} = $ 4-11），并且可以在最后的$ \ sillsim $ 8 Myr中保留碰撞的签名，$ \ textrm {h} h} \ scriptStyle \ scriptStyle \ mathrm {I}共露$ _2 $ $ x_ {co，b} =（3.4 \ pm 0.2）\ times 10^{20} $ cm $^{ - 2} $（k km s $^{ - 1} $）$^{ - 1} $^{ - 1} $ co-n 9 $ s $ s $ _2 $ _2 $ _2 $ _2 $ 16,600 \ pm 2,400 \ m_ \ odot $。我们得出了最近的（$ \ lyssim 1 $ Myr）星形的形成率$ 130 \ pm 30 \ m _ {\ odot} $ myr $^{ - 1} $，效率为8 $ \ pm $ 3 \％，通过比较总YSO质量质量与总分子气质量进行比较。在团块性能或PMS星年年龄与NGC 602的距离之间，很少有重大的径向趋势。我们找不到在最年轻的（$ \ lesssim $ 2 Myr）恒星中触发恒星形成场景的证据，而是得出结论认为，NGC 602在该区域中直接导致该区域的序列恒星形成过程可能并不可能导致该区域中。
NGC 602 is a young, low-metallicity star cluster in the "Wing" of the Small Magellanic Cloud. We reveal the recent evolutionary past of the cluster through analysis of high-resolution ($\sim$0.4 pc) Atacama Large Millimeter/submillimeter Array observations of molecular gas in the associated $\textrm{H}\scriptstyle\mathrm{II}$ region N90. We identify 110 molecular clumps ($R <$ 0.8 pc) traced by CO emission, and study the relationship between the clumps and associated young stellar objects (YSOs) and pre-main-sequence (PMS) stars. The clumps have high virial parameters (typical $α_{\rm{vir}} = $ 4-11) and may retain signatures of a collision in the last $\lesssim$8 Myr between $\textrm{H}\scriptstyle\mathrm{I}$ components of the adjacent supergiant shell SMC-SGS 1. We obtain a CO-bright-to-H$_2$ gas conversion factor of $X_{CO,B} = (3.4 \pm 0.2) \times 10^{20}$ cm$^{-2}$ (K km s$^{-1}$)$^{-1}$, and correct observed clump properties for CO-dark H$_2$ gas to derive a total molecular gas mass in N90 of $16,600 \pm 2,400 \ M_\odot$. We derive a recent ($\lesssim 1$ Myr) star formation rate of $130 \pm 30 \ M_{\odot}$ Myr$^{-1}$ with an efficiency of 8 $ \pm$ 3\% assessed through comparing total YSO mass to total molecular gas mass. Very few significant radial trends exist between clump properties or PMS star ages and distance from NGC 602. We do not find evidence for a triggered star formation scenario among the youngest ($\lesssim$2 Myr) stellar generations, and instead conclude that a sequential star formation process in which NGC 602 did not directly cause recent star formation in the region is likely.
