Galactic Warps and Polar Rings

人们普遍认为，Sparke星系有看不见的“暗”晕，其中包含了系统的大部分质量。光晕比发光物质延伸得更广，它的质量分布最好通过研究恒星和气体的最外层轨道来探测。螺旋星系中的扭曲盘和SO星系周围的极环的模型表明，这些可以被理解为大质量晕势中的自引力结构。翘曲环或极环的预期形式，以及这些结构内轨道的速度，取决于质量在看不见的光晕内的分布：取决于中心的集中，取决于与圆盘平面垂直的平坦度，取决于它是否明显是三轴的。将为理论建模和观测提供支持。关于翘曲的理论工作将解决星系凸起的影响，具有不同方位依赖性的翘曲，以及由于与晕的相互作用而导致的翘曲的最终阻尼。翘曲系统的光学和HI观测也将进行。极地环的动力学模拟将集中于三轴性的影响，以及为特定观测系统建立参数的详细模型；观测计划包括环的高分辨率HI测绘，无线电调查，光学成像和光谱学

9320403 Sparke Galaxies are widely believed to have unseen 'dark' halos containing much of the mass of the system. The halo is more extended than the luminous material, and its mass distribution is best probed by studying the outermost orbits of stars and gas. Models for warped disks in spiral galaxies, and for polar rings around SO galaxies, show that these can be understood as self- gravitating structures in the potential of the massive halo. The form expected for the warp or the polar ring, and velocities of orbits within these structures, depend on how mass is distributed within the unseen halo: on the central concentration, on the flattening normal to the disk plane, on whether it is significantly triaxial. Support will be provided both for theoretical modeling and observations. Theoretical work on warps will address the effect of a galactic bulge, warps with different azimuthal dependences, and the eventual damping of warps due to interaction with the halo. Optical and HI observations of warped systems will also be made. Dynamical modeling of polar rings will concentrate on the effect of triaxiality, and on detailed models for particular observed systems to establish parameters; the observational program includes high-resolution HI mapping of the rings, radio surveys, and optical imaging and spectroscopy