天文学进展Issue(2)：125-140,16.DOI:10.3969/j.issn.1000-8349.2013.02.01
星系自转曲线之观测研究进展
Developments in Observations and Studies of Rotation Curves of Galaxies
摘要
Abstract
The rotation curve of a galaxy describes how the rotational velocity V(R) of its matter depends on the distance R from the galaxy center, and represents evidence for the mass distribution within the galaxy and can be used for studying its kinematics and dynamics characteristics and inferring its evolutionary history. Both optical and radio observations of rotation velocities within galaxies can be used to derive their V(R), by using absorption lines such as H and K lines and emission lines such as Hα, HI and CO lines. A brief review of developments in observations and studies of rotation curves of galaxies is given in this paper. <br> Generally speaking, the V(R) curve increases monotonically and steeply in the central region of a galaxy out to a distance Rt of the turnover point, at which the V(R) reaches a maximum value Vmax, and beyond Rt the velocity either remains constant or varies gradually with a small amplitude, which is usually called as the flat rotation curve. <br> The major researches on rotation curves have been done for spiral galaxies. It has been found that the maximum velocity Vmax increases from the late type spirals to early ones, which are of some 300,220 and 175 km·s−1 respectively for Sa, Sb, and Sc galaxies. Besides normal spirals, galax-ies with various Hubble types also show rotations in some way, including barred spiral, elliptical, lenticular and irregular galaxies. <br> Since the 1970s the difference between the matter distribution implied by the luminosity and that implied by the flat rotation curve has been used as strong evidence that galaxies are embedded in extended halos of dark matter, because without such massive dark halos, rotation velocities in the outer regions of galaxies should show the Keplerian falloff. However, some people argue such an explanation for the flat rotation curve, and believe that the models without dark matter are also able to satisfactorily reproduce the observed kinematics in most cases. Moreover, someone pointed out that there is also a possibility that the rotation of galaxies in the outmost regions could be derived by a non-gravitational effect –magnetic fields, not gravitationally by dark matter. <br> In addition to what mentioned above, some important issues on rotation curves of galaxies are briefly described or discussed. These include (1) Is there a universal rotation curve for spirals, which means that the profiles of rotation curves of spirals are dependent upon the unique globe parameter—galaxy luminosity? (2) Environmental effects on rotation curves of galaxies in clusters, such as distances of galaxies from the cluster center and gravitational interaction among galaxies. (3) The vertical changes of galaxy rotation curves, i.e. a vertical gradient or falloff in rotation speed from the mid-plane of a galaxy. (4) Exploring the distribution of dark matter in galaxies from studies on rotation curves, and the distribution is very likely different from galaxy to galaxy.关键词
星系/旋涡星系/自转曲线/中性氢/暗晕Key words
galaxy/spiral galaxy/rotation curve/neutral hydrogen/dark halo分类
天文与地球科学引用本文复制引用
赵君亮..星系自转曲线之观测研究进展[J].天文学进展,2013,(2):125-140,16.基金项目
国家自然科学基金(10773020，10778003，10833055) （10773020，10778003，10833055）
