Acceleration of Relativistic Protons during the 20 January 2005 Flare and CME

The origin of relativistic solar protons during large flare/CME events has not been uniquely identified so far.We perform a detailed comparative analysis of the time profiles of relativistic protons detected by the worldwide network of neutron monitors at Earth with electromagnetic signatures of particle acceleration in the solar corona during the large particle event of 20 January 2005. The intensity-time profile of the relativistic protons derived from the neutron monitor data indicates two successive peaks. We show that microwave, hard X-ray and gamma-ray emissions display several episodes of particle acceleration within the impulsive flare phase. The first relativistic protons detected at Earth are accelerated together with relativistic electrons and with protons that produce pion decay gamma-rays during the second episode. The second peak in the relativistic proton profile at Earth is accompanied by new signatures of particle acceleration in the corona within approximatively 1 solar radius above the photosphere, revealed by hard X-ray and microwave emissions of low intensity, and by the renewed radio emission of electron beams and of a coronal shock wave. We discuss the observations in terms of different scenarios of particle acceleration in the corona.Comment: 22 pages, 5 figure

Limb Spicules from the Ground and from Space

We amassed statistics for quiet-sun chromosphere spicules at the limb using ground-based observations from the Swedish 1-m Solar Telescope on La Palma and simultaneously from NASA's Transition Region and Coronal Explorer (TRACE) spacecraft. The observations were obtained in July 2006. With the 0.2 arcsecond resolution obtained after maximizing the ground-based resolution with the Multi-Object Multi-Frame Blind Deconvolution (MOMFBD) program, we obtained specific statistics for sizes and motions of over two dozen individual spicules, based on movies compiled at 50-second cadence for the series of five wavelengths observed in a very narrow band at H-alpha, on-band and in the red and blue wings at 0.035 nm and 0.070 nm (10 s at each wavelength) using the SOUP filter, and had simultaneous observations in the 160 nm EUV continuum from TRACE. The MOMFBD restoration also automatically aligned the images, facilitating the making of Dopplergrams at each off-band pair. We studied 40 H-alpha spicules, and 14 EUV spicules that overlapped H-alpha spicules; we found that their dynamical and morphological properties fit into the framework of several previous studies. From a preliminary comparison with spicule theories, our observations are consistent with a reconnection mechanism for spicule generation, and with UV spicules being a sheath region surrounding the H-alpha spicules

Three-dimensional chromospheric magnetic field configurations based on photospheric-vector and chromospheric-multi-level longitudinal-magnetic field observations

The three-dimensional (3D) reconstruction of magnetic configurations above the photosphere is considered within the framework of the nonlinear force-free-field (FFF) model. The physical- computational algorithm proposed and tested incorporates, for the first time, the following basic features: 1) Both photospheric vector field, ${\vec B} (x,y,0)$ and chromospheric line of sight field component, $B_{z} (x,y,z)$ data are utilized; this reduces significantly the degree of ill-posedness characterizing the Cauchy problem corresponding to the case when only ${\vec B} (x,y,0)$ - values are used as boundary conditions. 2) A high-order, very efficient computational algorithm is developed and used: horizontal derivatives are evaluated by 14 - terms formulas in 14 different forms, selected such as to provide optimal computational accuracy; the vertical integration is achieved by the use of “moving" 10 - term formulas expressed in terms of 10 derivatives and the first $B_{i} (x,y,z)$ values $(i=x,y,z)$. 3) At neutral points, where inherent computational singularities in the values of the FFF-function α arise, rather than using smoothing techniques based on four-neighbouring- values averages, suitable procedures ensuring continuity are developed and used. The overall result of the incorporation of these novel features is an improvement by orders of magnitude of the accuracy with which the chromospheric fields are reconstructed in the case in which one uses (i) only ${\vec B} (x,y,0)$ - values as boundary conditions and (ii) relative simple computational formulas and smoothing techniques; at $\bar{z} = 20$, $\Delta B_{i} / B_{i} < 10^{-3}$ ! The elimination/minimization of measurement errors as well as the fitting of the corrected date to FFF-model-states is also discussed