2011MNRAS.415.3879P

We present a two-component gasdynamic model of an interstellar cloud embedded in hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, and that the interstellar plasma is quasi-neutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic fields and radiative processes are ignored in the model. We study the influence of heat conduction within the plasma on the interaction between a cloud and the plasma. We consider the extreme case and assume that hot plasma electrons instantly heat the plasma in the interaction region and that plasma flow can be described as isothermal. Using the two-component model of the interaction of cold neutral cloud and hot plasma, we estimate the lifetime of interstellar clouds. We focus on the clouds typical of the cluster of Local interstellar clouds embedded in the hot Local Bubble and give an estimate of the lifetime of the Local interstellar cloud where the Sun currently travels.

The charge transfer between the highly charged plasma ions and the neutral atoms generates X-ray emission. We assume a typical abundance of heavy ions for the Local Bubble plasma and estimate the X-ray emissivity due to charge exchange from the interface between the cold neutral cloud and the hot plasma. Our results show that charge exchange X-ray emission from the neutral–plasma interfaces can be a non-negligible fraction of the observed X-ray emission.