Testing for an attractor in the solar wind flow

Abstract

We analyse a time series of velocity fluctuations of the low-speed stream of the solar wind measured by the Helios spacecraft in the inner heliosphere. We use moving average and singular-value decomposition filters to give a faithful representation of the solar wind nonlinear behaviour. We have supported our previous result that trajectories describing the system in the inertial manifold of phase space can asymptotically approach the attractor of low-dimension. The obtained characteristics of the attractor are significantly different from those of the surrogate data. Thus these results suggest that the inner heliosphere is nonlinear and possibly a deterministic chaotic system.