Time-dependent hydrodynamical simulations of slow solar wind, coronal inflows, and polar plumes

¹ Observatoire de Paris, LUTH, CNRS, 92195 Meudon, France e-mail: rui.pinto@obspm.fr
² Space Science Division, Naval Research Laboratory,Washington, DC 20375-5352, USA e-mail: yi.wang@nrl.navy.mil

Received: 17 October 2008
Accepted: 21 February 2009

Abstract

Aims. We explore the effects of varying the areal expansion rate and coronal heating function on the solar wind flow.

Methods. We use a one-dimensional, time-dependent hydrodynamical code. The computational domain extends from near the photosphere, where nonreflecting boundary conditions are applied, to 30 , and includes a transition region where heat conduction and radiative losses dominate.

Results. We confirm that the observed inverse relationship between asymptotic wind speed and expansion factor is obtained if the coronal heating rate is a function of the local magnetic field strength. We show that inflows can be generated by suddenly increasing the rate of flux-tube expansion and suggest that this process may be involved in the closing-down of flux at coronal hole boundaries. We also simulate the formation and decay of a polar plume, by including an additional, time-dependent heating source near the base of the flux tube.