An investigation of the fine ray structure of the coronal streamer belt using LASCO data

Abstract

It is shown that within R>3–4 R⊙from the solar center the coronal streamer belt consists in a sequence of radial brightness rays. A minimum angular size of the individual ray d≈2.0°–2.5°, which is about the same in the directions normal to and along the streamer-belt, is independent of the distance from the Sun at R=4–6 R⊙. The lifetime of the rays can exceed 10 days. From time to time, inhomogeneities of material inside the rays begin to move in the antisunward direction. Plots of increase in their velocity with the distance from the Sun are similar to those obtained by Sheeley et al. (1997) for inhomogeneities that are carried by a quasi-stationary solar wind in streamers. It is concluded that the phenomena discussed in this paper and by Sheeley et al. (1997) share a common origin. It is suggested that a different origin of solar wind flows in streamers and in coronal holes may be associated with a different character of flows in microtubes of the magnetic field comprising a total solar wind flow. These tubes are observed as brightness rays in streamer belts and plumes in coronal holes.