Related papers: Magnetic Influences on the Solar Wind (Ph.D. Disse…

The origin and evolution of the 1/f power law observed in the energy spectrum of solar coronal and solar wind fluctuations at scales of around an hour is not entirely understood. Several existing theories aim at explaining it, involving…

Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic ``flocculated'' fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfv\'en critical zone, and…

We make use of the Parker Solar Probe (PSP) data to explore the nature of solar wind turbulence focusing on the Alfv\'enic character and power spectra of the fluctuations and their dependence on distance and context (i.e. large scale solar…

Motivated by theoretical, numerical, and observational evidence, we explore the possibility that the critical transition between sub-Alfv\'enic flow and super-Alfv\'enic flow in the solar atmosphere takes place in fragmented and…

As fundamental parameters of the Sun, the Alfv\'en radius and angular momentum loss determine how the solar wind changes from sub-Alfv\'enic to super-Alfv\'enic and how the Sun spins down. We present an approach to determining the solar…

The fast solar wind's high speeds and nonthermal features require that significant heating occurs well above the Sun's surface. Two leading theories seem incompatible: low-frequency "Alfv\'enic" turbulence, which transports energy outwards…

We have recently passed the 75th anniversary of one of the most important results in solar and space physics: Hannes Alfv\'en's discovery of Alfv\'en waves and the Alfv\'en speed. To celebrate the anniversary, this article recounts some…

Alfven waves created by sub-photospheric motions or by magnetic reconnection in the low solar atmosphere seem good candidates for coronal heating. However, the corona is also likely to be heated more directly by magnetic reconnection, with…

We present a novel method to evaluate the Alfven speed and the magnetic field strength along the streamer plasma sheet in the outer corona. The method is based on recent observations of streamer waves, which are regarded as the fast kink…

Vortex motions are frequently observed on the solar photosphere. These motions may play a key role in the transport of energy and momentum from the lower atmosphere into the upper solar atmosphere, contributing to coronal heating. The lower…

The propagation and the evolution of Alfvenic pulses in the solar coronal arcades is investigated by means of MHD numerical simulations. Significant transverse oscillations in coronal loops, triggered by nearby flare events, are often…

Magnetic fields are key ingredients for heating the solar corona to temperatures of several million Kelvin. A particularly important region with respect to this is the so-called magnetic canopy below the corona, where sound and Alfv\'en…

Estimating Alfven speeds is of interest in modelling the solar corona, studying the coronal heating problem and understanding the initiation and propagation of coronal mass ejections (CMEs). We assume here that the corona is in a…

Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude…

Two of the central problems in our understanding of the solar chromosphere are how the upper chromosphere is heated and what drives spicules. Estimates of the required chromospheric heating, based on radiative and conductive losses suggest…

The acceleration of the solar coronal plasma to supersonic speeds is one of the most fundamental yet unresolved problem in heliophysics. Despite the success of Parker's pioneering theory on an isothermal solar corona, the realistic solar…

The fast solar wind shows a wide spectrum of transverse magnetic and velocity field perturbations. These perturbations are strongly correlated in the sense of Alfv\'en waves propagating mostly outward, from the Sun to the interplanetary…

Collisionless dissipation of turbulence is important for heating plasmas in astrophysical, space physics, and laboratory environments, controlling energy, momentum and particle transport. We analyze Parker Solar Probe observations to…

Evidence for the presence of ion cyclotron waves, driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the…

Solar wind ions are observed to be heated in the directions perpendicular to the large-scale magnetic field, with preferential heating given to heavy ions. In the solar corona, this heating may be responsible for the generation of the wind…