Interstellar Medium in the vicinity of the solar system varies. Observations show that the Sun is moving at a speed of about 25 km / s through the local interstellar cloud, and can leave it in the next 10 thousand years. Significant role in the interaction of the solar system from interstellar matter plays solar wind.
Solar wind is the flow of charged particles (mostly hydrogen and helium plasma), with the enormous speed of expiring solar corona. The speed of the end does not depend on the distance from the Sun and, on average, equal to 450 km / sec. This speed exceeds the speed of sound in the interstellar medium. And if you imagine the clash of the interstellar medium and solar wind as the collision of two streams, then their interaction with shock waves occur. and the environment itself can be divided into three areas: the area where there is only a particle, FHI, the region where only particles of stellar wind and the area of their interaction.
And if the interstellar gas was fully ionized, as originally anticipated, it was the be all exactly as it was described above. But, as demonstrated by the first observation of the interplanetary medium Ly-aplha, neutral particles penetrate the interstellar medium in the solar system. In other words the sun interacts with the neutral and ionized gas in many ways.