标题： 盘星系中盘外气体旋转的流体静力模型 显示英文标题

标题： Hydrostatic models for the rotation of extra-planar gas in disk galaxies

摘要： 我们展示了流体静态模型能够重现螺旋星系盘外气体旋转速度的观测到的负垂直梯度。 我们构建了基于这样一个简单条件的模型：介质的压力不单单依赖于密度（而是具有涡旋压特性而非等温压特性：等密度面和等温面不重合）。 作为一个例子，我们成功地应用我们的方法来重现NGC 891落后的气态晕的观测速度梯度。 这里讨论的流体静态模型可以描述一个热的均匀介质，也可以描述由离散的冷HI云组成的“气体”，这些云具有各向同性的速度弥散分布。 尽管这里提出的方法生成了一个与观测约束一致的密度和速度场，但这些配置的稳定性仍然是一个开放的问题。 显示英文摘要

摘要： We show that fluid stationary models are able to reproduce the observed, negative vertical gradient of the rotation velocity of the extra-planar gas in spiral galaxies. We have constructed models based on the simple condition that the pressure of the medium does not depend on density alone (baroclinic instead of barotropic solutions: isodensity and isothermal surfaces do not coincide). As an illustration, we have successfully applied our method to reproduce the observed velocity gradient of the lagging gaseous halo of NGC 891. The fluid stationary models discussed here can describe a hot homogeneous medium as well as a "gas" made of discrete, cold HI clouds with an isotropic velocity dispersion distribution. Although the method presented here generates a density and velocity field consistent with observational constraints, the stability of these configurations remains an open question.