Showing papers on "Stellar-wind bubble published in 1975"

Local interstellar medium

Abstract: NEUTRAL interstellar hydrogen can be prevented from penetrating freely into the heliosphere of solar plasma, because it is partially coupled to the subsonic flow of interstellar plasma. Results from modelling the backscattering of the diffuse Lyman-α radiation are therefore unreliable. The interstellar density of H+ is probably 0.02 cm−3 or less, and the density of neutral hydrogen greater than 0.2 cm−3.

Theoretical Studies of the Large-Scale Behavior of the Solar Wind

Abstract: Publisher Summary This chapter discusses theoretical studies of the large-scale behavior of the solar wind. The transition between the sun and nearby interstellar matter is largely governed by the steady expansion of the hot tenuous outer atmosphere (corona) of the sun. This expansion starts low in the corona, slowly at first, and then accelerates outward. The flow passes continuously into a supersonic state and continues flowing outward as a supersonic “solar wind.” The solar wind persists far from the sun, certainly beyond the orbit of the earth, and must eventually make a transition to the local interstellar medium. This picture of the solar environment is very likely applicable to many other stars that are similar to the sun. In this chapter, critical comments on the basic assumptions of various solar wind models are presented. The chapter is a survey primarily of theoretical work aimed at understanding the large-scale dynamics of the solar wind. The emphasis is mainly on the acceleration, heating, angular momentum transfer, and termination of the wind. Topics such as the interplanetary magnetic field, fluctuations of the solar wind, and the origin of the solar wind are discussed only to an extent as they are related to the main topic of the chapter.

Solar Wind Heating at Mid-Heliospheric Distances Due to Secondary Ions

Abstract: Amongst the various solar wind models that have been discussed in the past the purely hydrodynamical ones proposed in their original form by Parker (1960) are generally favoured up to the present. This is because the main features of the solar wind observed near the Earth’s orbit can more satisfactorily be described by this kind of models without the need of too many ad-hoc assumptions. Special disadvantages that could not be overcome in exospheric treatments of the solar wind expansion up to now are that exospheric models are very sensitive to boundary conditions at the solar coronal base and that they do not include mixing of thermal velocities of different orientations to the magnetic field and coupling between thermal velocities of electrons and protons.