More than mass proportional heating of heavy ions by supercritical collisionless shocks in the solar corona

We propose a new model for explaining the observations of more than mass proportional heating of heavy ions in the polar solar corona. We point out that a large number of small scale intermittent shock waves can be present in the solar corona. The energization mechanism is, essentially, the ion reflection off supercritical quasi-perpendicular collisionless shocks in the corona and the subsequent acceleration by the motional electric field ${\bf E} = - (1/c) {\bf V} \times {\bf B}$. The acceleration due to ${\bf E}$ is perpendicular to the magnetic field, in agreement with observations, and is more than mass proportional with respect to protons, because the heavy ion orbit is mostly upstream of the quasi-perpendicular shock foot. The observed temperature ratios between O$^{5+}$ ions and protons in the polar corona, and between $\alpha$ particles and protons in the solar wind are easily recovered.Comment: 11 pages, 2 figure

Self-similar transport processes in a two-dimensional realization of multiscale magnetic field turbulence

We present the results of a numerical investigation of charged-particle transport across a synthesized magnetic configuration composed of a constant homogeneous background field and a multiscale perturbation component simulating an effect of turbulence on the microscopic particle dynamics. Our main goal is to analyze the dispersion of ideal test particles faced to diverse conditions in the turbulent domain. Depending on the amplitude of the background field and the input test particle velocity, we observe distinct transport regimes ranging from subdiffusion of guiding centers in the limit of Hamiltonian dynamics to random walks on a percolating fractal array and further to nearly diffusive behavior of the mean-square particle displacement versus time. In all cases, we find complex microscopic structure of the particle motion revealing long-time rests and trapping phenomena, sporadically interrupted by the phases of active cross-field propagation reminiscent of Levy-walk statistics. These complex features persist even when the particle dispersion is diffusive. An interpretation of the results obtained is proposed in connection with the fractional kinetics paradigm extending the microscopic properties of transport far beyond the conventional picture of a Brownian random motion. A calculation of the transport exponent for random walks on a fractal lattice is advocated from topological arguments. An intriguing indication of the topological approach is a gap in the transport exponent separating Hamiltonian-like and fractal random walk-like dynamics, supported through the simulation.Comment: 10 pages (including cover page), 7 figures, improved content, accepted for publication in Physica Script

Observational features of equatorial coronal hole jets

Collimated ejections of plasma called "coronal hole jets" are commonly observed in polar coronal holes. However, such coronal jets are not only a specific features of polar coronal holes but they can also be found in coronal holes appearing at lower heliographic latitudes. In this paper we present some observations of "equatorial coronal hole jets" made up with data provided by the STEREO/SECCHI instruments during a period comprising March 2007 and December 2007. The jet events are selected by requiring at least some visibility in both COR1 and EUVI instruments. We report 15 jet events, and we discuss their main features. For one event, the uplift velocity has been determined as about 200 km/s, while the deceleration rate appears to be about 0.11 km/s2, less than solar gravity. The average jet visibility time is about 30 minutes, consistent with jet observed in polar regions. On the basis of the present dataset, we provisionally conclude that there are not substantial physical differences between polar and equatorial coronal hole jets.Comment: 9 pages, 8 figures, 1 table, accepted for publication in Annales Geophysicae, Special Issue:'Three eyes on the Sun-multi-spacecraft studies of the corona and impacts on the heliosphere

Parameter estimation of superdiffusive motion of energetic particles upstream of heliospheric shocks

In-situ spacecraft observations recently suggested that the transport of energetic particles accelerated at heliospheric shocks can be anomalous, i.e. the mean square displacement can grow non-linearly in time. In particular, a new analysis technique has permitted the study of particle transport properties from energetic particle time profiles upstream of interplanetary shocks. Indeed, the time/spatial power laws of the differential intensity upstream of several shocks are indicative of superdiffusion. A complete determination of the key parameters of superdiffusive transport comprises the power-law index, the superdiffusion coefficient, the related transition scale at which the energetic particle profiles turn to decay as power laws, and the energy spectral index of the shock accelerated particles. Assuming large-scale spatial homogeneity of the background plasma, the power-law behaviour can been derived from both a (microscopic) propagator formalism and a (macroscopic) fractional transport equation. We compare the two approaches and find a relation between the diffusion coefficients used in the two formalisms. Based on the assumption of superdiffusive transport, we quantitatively derive these parameters by studying energetic particle profiles observed by the Ulysses and Voyager 2 spacecraft upstream of shocks in the heliosphere, for which a superdiffusive particle transport has previously been observed. Further, we have jointly studied the electron energy spectra, comparing the values of the spectral indices observed with those predicted by the standard diffusive shock acceleration theory and by a model based on superdiffusive transport. For a number of interplanetary shocks and for the solar wind termination shock, for the first time we obtain the anomalous diffusion constants and the scale at which the probability of particle free paths changes to a power-law...Comment: 5 Figure

The role of oxygen ions in the formation of a bifurcated current sheet in the magnetotail

Cluster observations in the near-Earth magnetotail have shown that sometimes the current sheet is bifurcated, i.e. it is divided in two layers. The influence of magnetic turbulence on ion motion in this region is investigated by numerical simulation, taking into account the presence of both protons and oxygen ions. The magnetotail current sheet is modeled as a magnetic field reversal with a normal magnetic field component $B_n$, plus a three-dimensional spectrum of magnetic fluctuations $\delta {\bf B}$, which represents the observed magnetic turbulence. The dawn-dusk electric field E$_y$ is also included. A test particle simulation is performed using different values of $\delta {\bf B}$, E$_y$ and injecting two different species of particles, O$^+$ ions and protons. O$^+$ ions can support the formation of a double current layer both in the absence and for large values of magnetic fluctuations ($\delta B/B_0 = 0.0$ and $\delta B/B_0 \geq 0.4$, where B$_0$ is the constant magnetic field in the magnetospheric lobes).Comment: 8 pages, 8 figures. J. Geophys. Res., in pres

At Zero Point: Discourse, Culture, and Satire in Restoration England

At Zero Point presents an entirely new way of looking at Restoration culture, discourse, and satire. The book locates a rupture in English culture and epistemology not at the end of the eighteenth century (when it occurred in France) but at the end of the seventeenth century. Rose Zimbardo’s hypothesis is based on Hans Blumenberg’s concept of “zero point”—the moment when an epistemology collapses under the weight of questions it has itself raised and simultaneously a new epistemology begins to construct itself. Zimbardo demonstrates that the Restoration marked both the collapse of the Renaissance order and the birth of modernism (with its new conceptions of self, nation, gender, language, logic, subjectivity, and reality). Using satire as the site for her investigation, Zimbardo examines works by Rochester, Oldham, Wycherley, and the early Swift for examples of Restoration deconstructive satire that, she argues, measure the collapse of Renaissance epistemology. Constructive satire, as exemplified in works by Dryden, has at its discursive center the “I” from which all order arises to be projected to the external world. No other book treats Restoration culture or satire in this way. Rose A. Zimbardo is SUNY Distinguished Teaching Professor Emerita whose previous books include A Mirror to Nature: Transformations in Drama and Aesthetics, 1660-1732. Zimbardo invites readers to examine concepts of gender, nation, self, and language in the literature of the Restoration period and be persuaded that its satire is both deconstructive and constructive. —Choice Stimulating and persuasive. —In-Between Effectively challenges easy assumptions of the referentiality of Restoration satire and drama and stresses the literary context. —Journal of English and Germanic Philology Only rarely does such a radical reexamination of culture occur, and Zimbardo\u27s At Zero Point brings new insights into both Renaissance and Restoration scholarship. —Rocky Mountain Review Zimbardo\u27s point is that we, like Wycherley\u27s generation, are at zero point, caught between a \u27deconstructive\u27 period—the 1960s, with their attack on \u27the strangling social fictions of the establishment\u27—and a reactionary one—the 1990s, era of \u27the new holy nationalism, conservatism, and racism.\u27 —Seventeenth-Century News An important and provocative book, with rewarding turns to authorship, gender, and nationalism. —Studies in English Literature One of the most ambitious books this year. . . . Stimulating and innovative, bringing an interesting mix of neglected and canonical texts to our attention. —Year’s Work in English Studieshttps://uknowledge.uky.edu/upk_english_language_and_literature_british_isles/1078/thumbnail.jp

On the influence of the plasma generated by comet Shoemaker-Levy 9 on Jupiter's magnetic field

The impact of comet Shoemaker-Levy 9 with Jupiter has created a variety of magnetospheric plasmas which were detected by their electromagnetic emissions. By means of the Dessler-Parker-Sckopke relation we estimate the perturbation of Jupiter’s magnetic field. It appears that the produced plasma may explain the observed decrease of UV lines in Io’s torus

Plasma transport in the interplanetary space: Percolation and anomalous diffusion of magnetic-field lines

The magnetic fluctuations due to, e.g., magnetohydrodynamic turbulence cause a magnetic-field line random walk that influences many cosmic plasma phenomena. The results of a three-dimensional numerical simulation of a turbulent magnetic field in plane geometry are presented here. Magnetic percolation, L´evy flights, and non-Gaussian random walk of the magnetic-field lines are found for moderate perturbation levels. In such a case plasma transport can be anomalous, i.e., either superdiffusive or subdiffusive. Increasing the perturbation level a Gaussian diffusion regime is attained. The implications on the structure of the electron foreshock and of planetary magnetopauses are discussed

Fractional Quantum Mechanics and Levy Path Integrals

The fractional quantum and statistical mechanics have been developed via new path integrals approach.Comment: 8 pages, added references for section