太阳银心距的多途径测定  

Approaches for measurements of the distance from the Sun to the Galactic Center

作　　者：赵君亮[1] 

机构地区：[1]中国科学院上海天文台

出　　处：《天文学进展》2009年第3期229-246,共18页Progress In Astronomy

基　　金：国家自然科学基金资助项目(10773020)

摘　　要：太阳银心距的测定对一些领域的天体物理研究具有不可替代的重要作用。在将近一个世纪的时间内,人们通过各种互相独立的途径,不断提高太阳银心距R_⊙测定(包括绝对测定和相对测定)值的精确度和可靠性。1985年IAU的推荐值为R_⊙=(8.5±1.1)Kpc;1993年Reid依据之前的多途径测定结果,得出其最优测定值可取为R_⊙=(8.0±0.5)kpc,且为嗣后的许多研究工作所采用。该文对有关工作给予简要的介绍和评述,并利用1993年以来R_⊙的各类测定结果得到最优估值R_⊙=(7.82±0.16)kpc。Since the seminal work of Shapley （1918） on the distribution of globular star clusters in the Milky Way Galaxy, from which R, the distance from the Sun to the Galactic center, was first estimated, astronomers have paid lots of effects to determine R as accurately as possible by using various methods. The importance of determining Re is that its value has close relationship with studies on astronomy and astrophysics, especially with some topics on Galactic and extragalactic distance scales. Since extragalactic distances are based on Galactic calibrations, the Hubble constant and Re are interrelated. Following what M. J. Reid did, methods used for measuring R can be categorized as primary measurements, secondary measurements and indirect measurements. The primary measurements are defined as a distance measured directly, with no secondary calibration such as ＂standard candle＂ calibration or Galactic rotation model, to a tracer at or very near to the Galactic center. It is an approach to absolutely estimate R. On the other side, secondary measurements of R need to use luminosity distances to sources whose distribution can be or are assumed to be symmetrical about the Galactic center. Obviously, this category belongs to relative estimation of R. Finally, indirect measurements combine different kinds of observations with a Galactic model or some other theoretical constrains. Before the end of the 20 century, the only tracers which can be used for absolute determination of R without any calibration are the H2O maser sources very near to the Galactic center, such as ones in Sgr B2. According to the principle of statistical parallax one can obtain a fairly precise estimate of R from proper motions and line-of-sight velocities of maser spots. Early in this century, values of R were determined from measurements of a star orbiting the compact radio source Sgr A＊ on the basis of the classical ＂orbiting binary＂ technique and from the central star cluster based on the statistical parallax method. So far as the

关 键 词：天体物理学 银河系 太阳银心距 

分 类 号：P156[天文地球—天文学]