We present a three-dimensional numerical model for the generation and evolution of the magnetic field in the solar convection zone, in which sunspots are produced and contribute to the cyclic reversal of the large-scale magnetic field. We then assess the impact of this dynamo-generated field on the structure of the solar corona and solar wind. This model solves the induction equation in which t...

We numerically model the coronal mass ejection (CME) event of October 28, 2003 that erupted from active region 10486 and propagated to Earth in less than 20 hours causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs from the same active region, one appr...

[1] The Heliospheric Imager (HI) instruments on board the STEREO spacecraft are used to analyze the solar wind during August and September 2007. We show how HI can be used to image the streamer belt and, in particular, the variability of the slow solar wind which originates inside and in the vicinity of the streamer belt. Intermittent mass flows are observed in HI difference images, streaming o...

Wave effects in a two-fluidmodel for the solar corona and wind are studied. Heating and acceleration are achieved by high-frequency Alfvén waves, which are assumed to be created through small-scale reconnections in the chromospheric network. The wave energy flux Fw is given in the model as a lower boundary condition. Waves with a power spectrum of the form P0(f/f0)−1 in the frequency range from...

[1] We present a comparison between two simulations of coronal mass ejections (CMEs), in the lower corona, driven by different flux rope mechanisms presented in the literature. Both mechanisms represent different magnetic field configurations regarding the amount of twist of the magnetic field lines and different initial energies. They are used as a “proof of concept” to explore how different i...

This paper describes the investigation of a DC surface corona discharge established on a rounded edge of a dielectric material. The ionic wind induced by the discharge was measured with the Particle Image Velocimetry system. A physical induced flow model is proposed to interpret the shape of the velocity field. Experiments on a flat plate and a NACA 0015 were performed in a subsonic wind tunnel...

The higher-order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically, scale by scale. We find a single global non-Gaussian scale-free behavior from minutes to over 5 h. This spans the signature of an inertial range of magnetohydrodynamic turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude flu...

Estimating the structure, or density distribution, of the solar corona from a set of 2D white light images made by coronagraphs is a critical challenge in coronal physics. This work describes new data analysis procedures which are used to create global maps of the coronal structure at heights where the corona becomes approximately radial (≥3R ). The technique, which is named Qualitative Solar R...

Fast solar wind has been recognized, about 40 years ago, to originate in polar coronal holes (CHs), that, since then, have been identified with sources of recurrent high speed wind streams. As of today, however, there is no general consensus about whether there are, within CHs, preferential locations where the solar wind is accelerated. Knowledge of slow wind sources is far from complete as wel...

We present an analytic description of turbulent, magnetohydrodynamic (MHD) disk accretion around black holes that specifically addresses the relationship between radial and vertical, mean-field transport of mass, momentum and energy, thereby complementing and extending numerical simulations. The azimuthal-vertical component of the magnetic stress is fundamental to an understanding of disk– coro...