The Structure of the Local Interstellar Medium IV: Dynamics, Morphology, Physical Properties, and Implications of Cloud-Cloud Interactions

摘要

We present an empirical dynamical model of the local interstellar mediumbased on 270 radial-velocity measurements for 157 sight lines toward nearbystars. Physical-parameter measurements (i.e., temperature, turbulent velocity,depletions) are available for 90 components, or one-third of the sample,enabling initial characterizations of the physical properties of LISM clouds.The model includes 15 warm clouds located within 15 pc of the Sun, each with adifferent velocity vector. We derive projected morphologies of all clouds andestimate the volume filling factor of warm partially ionized material in theLISM to be between ~5.5% and 19%. Relative velocities of potentiallyinteracting clouds are often supersonic, consistent with heating, turbulent,and metal-depletion properties. Cloud-cloud collisions may be responsible forthe filamentary morphologies found in ~1/3 of LISM clouds, the distribution ofclouds along the boundaries of the two nearest clouds (LIC and G), the detailedshape and heating of the Mic Cloud, the location of nearby radio scintillationscreens, and the location of a LISM cold cloud. Contrary to previous claims,the Sun appears to be located in the transition zone between the LIC and GClouds.