银河系旋臂结构和运动学的VLBI高精度探测  

Probing the Spiral Structure and Kinematics of the Milky Way with VLBI Techniques

作　　者：徐烨[1] 

机构地区：[1]中国科学院紫金山天文台,南京210008

出　　处：《天文学进展》2011年第2期123-131,共9页Progress In Astronomy

基　　金：国家自然科学基金(11073054;10733030);国家自然科学基金创新群体(10621303);973计划(2007CB815403)

摘　　要：直接测量恒星形成区的距离,从而确定银河系的旋臂结构以及银河系运动学的工作正在逐步展开。通过对恒星形感区脉泽的多历元VLBI观测,利用类星体和脉泽相位参考技术,精确地测定脉泽的位置、自行和视差。精确的距离能够确定旋臂的位置,从而建立银河系旋臂结构的新模型;运用绝对自行确定该处天体的三维运动,由此精确测定银河系的旋转曲线,导出银河系总质量和暗物质质量等基本物理参数。最近的初步结果表明银河系运动速度比以前认为的更快,质量也更大。A large project is being carried out by several groups throughout the world.The goal is to reinforce the foundations of models of the spiral structure of the Milky Way by measuring distances directly to regions of star formation across the Milky Way using VLBI techniques.The way is to determine trigonometric parallaxes to strong maser sources,which are associated with regions of star formation and their attendant HII regions.With accurate distances,one should be able to determine the locations of the spiral arms,and produce an extensive map of the 3- dimensional structure of bright material associated with young stars that define spiral structure. In addition to distances,the project also yields excellent measurements of secular proper motions, with accuracies of 1 km·s^（-1）.Combining radial velocity measurements with proper motions（and distances） yields full 3-dimensional velocities,relative to the motion of the Sun.Thus,through this project,one will also determine the full kinematics of star forming regions in the Milky Way,which will accurately define the rotation curve of the Milky Way and,in turn,its enclosed mass as a function of Galactocentric radius.Finally,one should be able to show how material in spiral arms actually moves,to characterize the occasional large kinematic anomalies（such as in the Perseus Arm）,and hopefully to understand why these anomalies occur.At present,the preliminary results indicate that our galaxy is more massive and spins much faster than previously thought.

关 键 词：银河系结构 三角视差 天体脉泽 

分 类 号：P145.2[天文地球—天体物理]