Galactic Warps and Polar Rings

小行星9320403 星系被广泛认为有看不见的“黑暗”光环，包含了系统的大部分质量。 晕比发光物质更广，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状，以及这些结构内的轨道速度，取决于看不见的晕内的质量分布：取决于中心浓度，取决于垂直于盘平面的扁平度，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。 翘曲的理论工作将解决的银河系隆起的影响，翘曲与不同的方位角的依赖性，并最终阻尼翘曲由于与晕的相互作用。 还将对翘曲系统进行光学和HI观测。 极环的动力学建模将集中于三轴性的影响，以及用于确定参数的特定观测系统的详细模型;观测计划包括环的高分辨率HI绘图、无线电勘测以及光学成像和光谱学

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