Related papers: Multi-strand coronal loop model and filter-ratio a…
Alfv\'en waves are widely believed to play an important role in the transport of energy from the solar photosphere to the corona through the partially ionized chromosphere. In previous work, the properties of torsional Alfv\'en waves were…
I report a coronal wave observed in Fexii, soft X-ray, and Halpha on November 6, 2006, jointly with a CME and a flare to show the spatial and temporal relation of the wave and the CME. I also take advantage of the spectral resolution of the…
Multi-wavelength solar images in the EUV are routinely used for analysing solar features such as coronal holes, filaments, and flares. However, images taken in different bands often look remarkably similar as each band receives…
All theories that attempt to explain the heating of the high temperature plasma observed in the solar corona are based on short bursts of energy. The intensities and velocities measured in the cores of quiescent active regions, however, can…
Between the base of the solar corona and the Alfven critical point, the solar-wind density decreases by approximately five orders of magnitude, but the temperature varies by a factor of only a few. In this paper, I show that such…
We study the temporal evolution of coronal loops using data from the Solar X-ray Imager (SXI) on board of GOES-12. This instrument allows us to follow in detail the full lifetime of coronal loops. The observed light curves suggest three…
The Soft X-ray intensity of loops in active region cores and corresponding footpoint, or moss, intensity observed in the EUV remain steady for several hours of observation. The steadiness of the emission has prompted many to suggest that…
Flare emissions in X-ray and EUV wavelengths have previously been modeled as the plasma response to impulsive heating from magnetic reconnection. Some flares exhibit gradually evolving X-ray and EUV light curves, which are believed to…
2.5-dimensional magnetohydrodynamic (MHD) simulations are performed with high spatial resolution in order to distinguish between competing models of the coronal heating problem. A single coronal loop powered by Alfv\'{e}n waves excited in…
Understanding the relationship between the magnetic field and coronal heating is one of the central problems of solar physics. However, studies of the magnetic properties of impulsively heated loops have been rare. We present results from a…
Alfven waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in…
Propagating slow waves in coronal loops exhibit a damping which depends upon the frequency of the waves. In this study we aim to investigate the relationship of the damping length (L$_d$) with the frequency of the propagating wave. We…
The theoretical expectation that coronal loops should expand with height contrasts with observations that typically show constant cross-sections. We investigate the idea that this discrepancy results from loops being composed of fine…
The Enthalpy Based Thermal Evolution of Loops (EBTEL) approximate model for static and dynamic coronal loops is developed to include the effect of a loop cross-sectional area which increases from the base of the transition region (TR) to…
We investigate the evolution of coronal loop emission in the context of the coronal magnetic field topology. New modeling techniques allow us to investigate the magnetic field structure and energy release in active regions. Using these…
We propose a novel one-dimensional model that includes both shock and turbulence heating and qualify how these processes contribute to heating the corona and driving the solar wind. Compressible MHD simulations allow us to automatically…
Cool stars like our Sun are surrounded by a million degree hot outer atmosphere, the corona. Since more than 60 years the physical nature of the processes heating the corona to temperatures well in excess of those on the stellar surface…
In the solar atmosphere, the chromospheric and coronal plasmas are much hotter than the visible photosphere. The heating of the solar atmosphere, including the partially ionized chromosphere and corona, remains largely unknown. In this…
We present three-dimensional, hybrid-kinetic numerical simulations of driven Alfv\'{e}n-wave turbulence of relevance to the collisionless near-Earth solar wind. Special attention is paid to the spectral transition that occurs near the…
The dynamical response of the solar corona to surface and sub-surface perturbations depends on the chromospheric stratification, and specifically on how efficiently these layers reflect or transmit incoming Alfv\'en waves. While it would be…