This study numerically investigates the formation of high-velocity molecular clouds(HVMCs)in the Galactic Center(GC)based on the X-ray emission analysis.We employ three-dimensional magnetohydrodynamic simulations to e...This study numerically investigates the formation of high-velocity molecular clouds(HVMCs)in the Galactic Center(GC)based on the X-ray emission analysis.We employ three-dimensional magnetohydrodynamic simulations to explore the propagation and acceleration of HVMCs with starburst-driven winds,considering vertical,horizontal,and no magnetic field scenarios.Our results reveal that the envelope gas(with a typical T~10~8 K and density~10^(-2)cm^(-3))of molecular clouds(MCs)as a result of the shock interaction is responsible for X-ray emission.Additionally,some clear boundary exists between the interstellar medium(ISM),envelope gas and MCs,and the envelope gas protects the MCs in the heated environment of the shock wave.In theory,it is challenging to distinguish between the envelope gas,MCs and ISM in terms of X-ray emission.Our simulations suggest that the envelope gas has a significant impact on the survival and emission characteristics of MCs,providing insights into the complex interactions from the supernova feedback mechanisms in the GC.展开更多
In our previous work,we identified~100,000 metal-poor stars([Fe/H]<-1.0)from the LAMOST Survey.This work estimates their chemical abundances and explores the origin and evolution of the Galactic metal-poor disk.Our...In our previous work,we identified~100,000 metal-poor stars([Fe/H]<-1.0)from the LAMOST Survey.This work estimates their chemical abundances and explores the origin and evolution of the Galactic metal-poor disk.Our chemo-dynamical analysis reveals four main populations within the metal-poor disk:(1)a primordial disk older than 12 Gyr with[Fe/H]>-1.5;(2)debris stars from the progenitor galaxy of Gaia±Sausage±Enceladus(GSE),but now residing in the Galactic disk;(3)the metal-poor tail of the metal-rich,high-αdisk formed10±12 Gyr ago,with metallicity lower limit extending to-2.0;(4)the metal-poor tail of the metal-rich,low-αdisk younger than 8 Gyr,reaching a lower metallicity limit of-1.8.These results reveal the presence of a primordial disk and show that both high-αand low-αdisks reach lower metallicities than previously thought.Analysis of merger debris reveals that Wukong,with extremely low metallicity,likely originates from merger events distinct from GSE.Additionally,three new substructures are identified:ShangGu-1,characterized by unusual[Fe/H]-eccentricity correlations;ShangGu-2,possibly heated disk stars;and ShangGu-3,which can be divided into four subgroups based on differing orbital directions,with two aligning with the previously known Nyx and Nyx-2.展开更多
银河系光行差,或称为长期光行差漂移,是由于太阳系质心绕着银河系中心做轨道运动的加速度引起的视自行效应,量级大约为5μas·yr-1.在21世纪之前,由于观测精度尚未达到如此高的程度,人们很少讨论银河系光行差效应.随着甚长基线干涉(...银河系光行差,或称为长期光行差漂移,是由于太阳系质心绕着银河系中心做轨道运动的加速度引起的视自行效应,量级大约为5μas·yr-1.在21世纪之前,由于观测精度尚未达到如此高的程度,人们很少讨论银河系光行差效应.随着甚长基线干涉(Very Long Baseline Interferometer,VLBI)在基本天文学中的广泛应用和欧洲空间局(European Space Agency,ESA)的第2代微角秒天体测量卫星Gaia的问世,该效应显得逐渐重要.由于河外源的分布不均匀,银河系光行差效应会使得河外源天球参考架缓慢旋转,进而需要修正地球岁差参数,其中岁差速率的改正值大约为1μas·yr-1.对于微角秒精度的VLBI和Gaia参考架,银河系光行差将会引起框架扭曲,在两者的连接过程中,也是必须考虑的系统效应.展开更多
基金the cosmology simulation database(CSD)in the National Basic Science Data Center(NBSDC)and its funds the NBSDC-DB-10the support from the National Key Research and Development Program of China(2022YFA1602930)+3 种基金the National Natural Science Foundation of China(NSFC,grant Nos.11825303 and 11861131006)the science research grants from the China Manned Space project with No.CMS-CSST 2021-A03,CMSCSST-2021-A04the Fundamental Research Funds for the Central Universities of China(2262022-00216)the startup funding of Zhejiang University。
文摘This study numerically investigates the formation of high-velocity molecular clouds(HVMCs)in the Galactic Center(GC)based on the X-ray emission analysis.We employ three-dimensional magnetohydrodynamic simulations to explore the propagation and acceleration of HVMCs with starburst-driven winds,considering vertical,horizontal,and no magnetic field scenarios.Our results reveal that the envelope gas(with a typical T~10~8 K and density~10^(-2)cm^(-3))of molecular clouds(MCs)as a result of the shock interaction is responsible for X-ray emission.Additionally,some clear boundary exists between the interstellar medium(ISM),envelope gas and MCs,and the envelope gas protects the MCs in the heated environment of the shock wave.In theory,it is challenging to distinguish between the envelope gas,MCs and ISM in terms of X-ray emission.Our simulations suggest that the envelope gas has a significant impact on the survival and emission characteristics of MCs,providing insights into the complex interactions from the supernova feedback mechanisms in the GC.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.11988101 and12222305)National Key R&D Program of China No.2024YFA1611900Guoshoujing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences。
文摘In our previous work,we identified~100,000 metal-poor stars([Fe/H]<-1.0)from the LAMOST Survey.This work estimates their chemical abundances and explores the origin and evolution of the Galactic metal-poor disk.Our chemo-dynamical analysis reveals four main populations within the metal-poor disk:(1)a primordial disk older than 12 Gyr with[Fe/H]>-1.5;(2)debris stars from the progenitor galaxy of Gaia±Sausage±Enceladus(GSE),but now residing in the Galactic disk;(3)the metal-poor tail of the metal-rich,high-αdisk formed10±12 Gyr ago,with metallicity lower limit extending to-2.0;(4)the metal-poor tail of the metal-rich,low-αdisk younger than 8 Gyr,reaching a lower metallicity limit of-1.8.These results reveal the presence of a primordial disk and show that both high-αand low-αdisks reach lower metallicities than previously thought.Analysis of merger debris reveals that Wukong,with extremely low metallicity,likely originates from merger events distinct from GSE.Additionally,three new substructures are identified:ShangGu-1,characterized by unusual[Fe/H]-eccentricity correlations;ShangGu-2,possibly heated disk stars;and ShangGu-3,which can be divided into four subgroups based on differing orbital directions,with two aligning with the previously known Nyx and Nyx-2.
文摘银河系光行差,或称为长期光行差漂移,是由于太阳系质心绕着银河系中心做轨道运动的加速度引起的视自行效应,量级大约为5μas·yr-1.在21世纪之前,由于观测精度尚未达到如此高的程度,人们很少讨论银河系光行差效应.随着甚长基线干涉(Very Long Baseline Interferometer,VLBI)在基本天文学中的广泛应用和欧洲空间局(European Space Agency,ESA)的第2代微角秒天体测量卫星Gaia的问世,该效应显得逐渐重要.由于河外源的分布不均匀,银河系光行差效应会使得河外源天球参考架缓慢旋转,进而需要修正地球岁差参数,其中岁差速率的改正值大约为1μas·yr-1.对于微角秒精度的VLBI和Gaia参考架,银河系光行差将会引起框架扭曲,在两者的连接过程中,也是必须考虑的系统效应.
