Coronal mass ejections: origins, evolution, and role in spaceweather

Coronal mass ejections (CMEs) are an important element of coronal and interplanetary dynamics. They can inject large amounts of mass and magnetic fields into the heliosphere, causing major geomagnetic storms and interplanetary shocks, which are a key source of solar energetic particles (E>1 MeV). Until recently, our understanding of the origins and early development of CMEs at the Sun was very limited. We knew that CMEs were frequently associated with erupting prominences and long-enduring X-ray arcades, but our physical understanding of how and why CMEs are initiated was poor. However, recent studies using the excellent data sets from the Yohkoh, SOHO, Wind, ACE and other spacecraft and ground-based instruments have improved our knowledge of the mass ejection process and how it effects space weather. The author reviews some of the well-determined coronal properties of CMEs, what is known about their source regions, and what their manifestations are in the solar wind. One exciting new type of observation is of halo-like CMEs, which suggest the launch of a geoeffective disturbance toward Earth. Several studies have shown a good correspondence between halo CMEs accompanied by near-sun center surface activity and subsequent magnetic clouds and geomagnetic storms at earth. In addition, halo CMEs are important for understanding the internal structure of CMEs since their source regions are near Sun center and near-earth spacecraft may be likely to sample material along their central axes     

Study of solar features causing GMSs with 250γ<<Emphasis Type="Italic">H</Emphasis><400γ

The effect of solar features on geospheric conditions leading to geomagnetic storms (GMSs) with planetary index,A ^P ≥ 20 and the range of horizontal component of the Earth’s magnetic fieldH such that 250γ <H < 400γ has been investigated using interplanetary magnetic field (IMF), solar wind plasma (SWP) and solar geophysical data (SGD) during the period 1978–99. Statistically, it is observed that maximum number of GMSs have occurred during the maximum solar activity years of 21st and 22nd solar cycles. A peculiar result has been observed during the years 1982, 1994 when sunspot numbers (SSNs) decrease very rapidly while numbers of GMSs increase. No distinct association between yearly occurrence of disturbed days and SSNs is observed. Maximum number of disturbed days have occurred during spring and rainy seasons showing a seasonal variation of disturbed days. No significant correlation between magnitude (intensity) of GMSs and importance ofH _α , X-ray solar flares has been observed. Maximum number of GMSs is associated with solar flares of lower importance, i.e., SF during the period 1978-93.H _α , X-ray solar flares occurred within lower helio-latitudes, i.e., (0–30)°N to (0–30)°S are associated with GMSs. NoH _α , X-ray solar flares have occurred beyond 40°N or 40°S in association with GMSs. In helio-latitude range (10–40)°N to (10–40)°S, the 89.5% concentration of active prominences and disappearing filaments (APDFs) are associated with GMSs. Maximum number of GMSs are associated with solar flares. Coronal mass ejections (CMEs) are related with eruptive prominences, solar flares, type IV radio burst and they occur at low helio-latitude. It is observed that CMEs related GMS events are not always associated with high speed solar wind streams (HSSWSs). In many individual events, the travel time between the explosion on the Sun and maximum activity lies between 58 and 118 h causing GMSs at the Earth.     

On “geometric” effects in the microwave radiation of active regions passing through the solar disk

Two basic “geometric” effects manifest themselves as slow variations in the properties of the microwave radiation of the active region passing through the solar disk, namely 1) sign inversions of the circular polarization and 2) characteristic peaks of the brightness temperature at certain longitudes on both sides of the central solar meridian and depression near it. These effects are related to the magnetic directivity of the cyclotron radiation governing in the centimeter wavelength range above large spots. The concept of “normal” passage of the active region through the solar disk is introduced in this paper on the basis of studying the mentioned effects observed at two wavelengths, 5.2 cm (Siberian Solar Radiotelescope, Buryatiya) and 1.76 cm (Radioheliograph in Nobeyama, Japan), to separate the “normal,” or “geometric” effects, in the behavior of the microwave radiation from the evolutional effects that may cause high-power solar flares. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 8, pp. 641–659, August 2008.     

Geomagnetically Induced Currents: Principles

The geospace, or the space environment near Earth, is constantly subjected to changes in the solar wind flow generated at the Sun. The study of this environment variability is called Space Weather. Examples of effects resulting from this variability are the occurrence of powerful solar disturbances, such as coronal mass ejections (CMEs). The impact of CMEs on the Earth’s magnetosphere very often greatly perturbs the geomagnetic field causing the occurrence of geomagnetic storms. Such extremely variable geomagnetic fields trigger geomagnetic effects measurable not only in the geospace but also in the ionosphere, upper atmosphere, and on and in the ground. For example, during extreme cases, rapidly changing geomagnetic fields generate intense geomagnetically induced currents (GICs). Intense GICs can cause dramatic effects on man-made technological systems, such as damage to high-voltage power transmission transformers leading to interruption of power supply, and/or corrosion of oil and gas pipelines. These space weather effects can in turn lead to severe economic losses. In this paper, we supply the reader with theoretical concepts related to GICs as well as their general consequences. As an example, we discuss the GIC effects on a North American power grid located in mid-latitude regions during the 13–14 March 1989 extreme geomagnetic storm. That was the most extreme storm that occurred in the space era age.     

Study of dynamics of global disturbances of the Earth’s magnetosphere using muon detectors

Amethod is developed, whichmakes it possible to predict in advance disturbances in the Earth’s magnetosphere, caused by solar flares or changes in the heliospheric magnetic field, since the cosmic particle flux reaches the Earth much earlier than coronal plasma bursts. To scan the celestial hemisphere, wide-aperture muon detectors are used. A unique system of muon hodoscopes was developed at the NEVOD Science and Education Center (MEPhI, Moscow). The data of the URAGAN muon hodoscope on two-dimensional dynamics of the muon flux during the Forbush effect of November 14, 2006 are analyzed. Changes in the muon flux intensity, measured at various directions with an interval of 30 min are shown. The results obtained demonstrate the muon flux sensitivity to solar plasma cloud motion, which offers prospects to use muon detectors to probe interplanetary space at long distances from the Earth and to predict geomagnetic disturbances.     

Unparticles in gauge theory

A field model for a quark and an antiquark binding is described. Quarks interact via a gauge unparticle (“ungluon”). The model is formulated in terms of Lagrangian which features the source field S(x) which becomes a local pseudo-Goldstone field of conformal symmetry — the pseudodilaton mode and from which the gauge non-primary unparticle field is derived by B _μ(x) ∼ ∂_μ S(x). Because the conformal sector is strongly coupled, the mode S(x) may be one of new states accessible at high energies. We have carried out an analysis of the important quantity that enters in the “ungluon” exchange pattern — the “ungluon” propagator.     

Modulation of galactic cosmic ray intensities by coronal mass ejections into interplanetary space

The data on the measurements of the intensities of galactic cosmic rays with proton energies greater than 30 MeV are compared with the data on the solar wind and interplanetary magnetic field measured on board the Vega-1 and Vega-2 automated interplanetary stations. Modulation structures with characteristic shapes and durations, namely quasi-symmetric (“bays”) short-term Forbush decreases of intensity, are revealed. It is shown that these Forbush decreases were recorded due to the stations flying through coronal mass-ejection regions. Original Russian Text ? E.A. Chuchkov, V.I. Tulupov, V.P. Okhlopkov, G.P. Lyubimov, 2009, published in Vestnik Moskovskogo Universiteta. Fizika, 2009, No. 3, pp. 90–93.     

Proton magnetic relaxation in a disperse “dry water” nanosystem

We have studied the characteristic features of proton magnetic relaxation in a disperse “dry water” nanosystem. We have determined the effect of the microstructure of the “dry water” on its NMR relaxation parameters.     

Electronic spectrum of a two-dimensional Fibonacci lattice

The electronic spectrum and wave functions of a new quasicrystal structure—a two-dimensional Fibonacci lattice—are investigated in the tight-binding approximation using the method of the level statistics. This is a self-similar structure consisting of three elementary structural units. The “central” and “nodal” decoration of this structure are examined. It is shown that the electronic energy spectrum of a two-dimensional Fibonacci lattice contains a singular part, but in contrast to a one-dimensional Fibonacci lattice the spectrum does not contain a hierarchical gap structure. The measure of allowed states (Lebesgue measure) of the spectrum is different from zero, and for “central” decoration it is close to 1. The character of the localization of the wave functions is investigated, and it is found that the wave functions are “critical.” Zh. éksp. Teor. Fiz. 116, 1834–1842 (November 1999)     

On the Stability of Realistic Three-Body Problems

We consider the system Sun—Jupiter—Ceres as an example of a planar, circular, restricted three-body problem and, after substituting the mass ratio of Jupiter/Sun (which is approximately 10^-3) with a parameter , we prove the existence of stable quasi-periodic motions with frequencies close to the observed (average) frequencies reported in “The Astronomical Almanac” for . The proof is “computer-assisted”. Received: 1 April 1996 / Accepted: 25 October 1996     

Non-physical consequences of the muffin-tin-type intra-molecular potential

We demonstrate, using a simple model, that, in the frame of muffin-tin-like potential, non-physical peculiarities appear in molecular photoionization cross-sections that are a consequence of “jumps” in the potential and its first derivative at some radius. The magnitude of non-physical effects is of the same order as the physical oscillations in the cross-section of a diatomicmolecule. The role of the size of these “jumps” is illustrated by choosing three values for it. The results obtained are connected to the previously studied effect of non-analytic behavior as a function of r, the potential V(r) acting upon a particle on its photoionization cross-section. In reality, such potential has to be analytic in magnitude and have a first derivative function in r. The introduction of non-analytic features in model V(r) leads to non-physical features — oscillations, additional maxima, and so forth — in the corresponding cross-section.     

太阳日冕物质抛射的磁流体力学性质

太阳是离地球最近的一颗恒星，太阳日冕物质抛射是太阳大气中最剧烈的一种活动现象．当日冕物质抛射爆发时，大量的等离子体物质从接近太阳日面的低日冕被抛出，瞬时释放出巨大的能量．当一部分这些物质和能量传播到地球附近时，可以造成短波通讯中断、卫星工作失常等破坏性现象．文章作者认为，是缠绕的太阳磁场提供了足够的能量，使这些日冕物质可以克服恒星的重力以及周边磁场的束缚抛射出来；而磁螺度在日冕中的不断积累，不仅为日冕物质抛射提供了能量基础，而且使爆发在一定程度上成为一种日冕演化的必然。     

Watching it boil: Continuous observation for the quantum zeno effect

The quantum Zeno effect (QZE) is often associated with the ironic maxim, “a watched pot never boils”, although the notion of “watching” suggests a continuous activity at odds with the usual (pulsed measurement) presentation of the QZE. We show how continuous watching can provide the same halting of decay as the usual QZE, and, for incomplete hindrance, we provide a precise connection between the interval between projections and the response time of the continuous observer. Thus, watching closely, but not so closely as to halt the “boiling”, is equivalent to—gives the same degree of partial hindrance as—pulsed measurements with a particular pulsing rate. Our demonstration is accomplished by treating the apparatus for the continuous watching as a fully quantum object. This in turn allows us a second perspective on the QZE, in which it is the modified level structure of the combined system/apparatus Hamiltonian that slows the decay. This and other considerations favor the characterization “dominated time evolution” for the QZE.     

Effects of interaction of nanoparticles in a highly anisotropic ferrimagnet

This paper reports on a study of the field and temperature dependences of the parameters of the particle magnetic interaction in a densely packed system of nanocrystals of the highly anisotropic hexagonal ferrite BaFe₁₂O₁₉ with the particles distributed in diameter within the range 10—100 nm and having volumes satisfying the criterion of “small Stoner—Wohlfarth particles.” It is shown that the resultant particle interaction in the temperature range 300 K≤T≤640 K has a negative sign, whereas for T>640 K, it is positive. The maximum values of the parameter Δm allow classification of the interaction as moderate in strength. The temperature dependences of the interaction parameters are found to correlate with manifestation of the size and surface effects in the system, which are characteristic of small particles (transition to the superparamagnetic state, “surface” anisotropy, and reduced exchange interaction in a structurally defective near-surface layer of particles).     

Prediction of geoeffective solar wind streams near earth according to solar observational data

A semi-empirical model for predicting solar wind (SW) streams is developed based on satellite images of the Sun and corona using a hierarchical approach. The model allows simultaneous calculation of the parameters of all three SW components, i.e., slow SW, high-speed streams from coronal holes, and interplanetary coronal mass ejections, as well as the detection of their possible interaction in the heliosphere.     

Detection of magneto-gravity waves in the ionosphere by analysis of the maximum observable frequencies on oblique-sounding paths

The existence of magneto-gravity waves stipulated by the substorm activity can lead to the occurrence of traveling ionospheric disturbances, whose velocity exceeds the sound speed. For detection of magneto-gravity waves, we used experimental data on propagation of decameter radio waves on the midlatitude and subauroral oblique sounding paths Inskip–Rostov-on-Don, Cyprus–Rostovon-Don, Irkutsk–Rostov-on-Don, and Norilsk–Rostov-on-Don in December 2006 and March 2007 under conditions of weak geomagnetic disturbance. Time delays between the AE indices of polar electrojets and the maximum observable frequencies for the considered paths were established by calculation of linear correlations. These delays correspond to the times required for transport of gravity disturbances from the auroral region to the reflection points of radio waves on respective paths. Among the obtained time shifts, we mention the 5–10-min ones which correspond to increased velocity of the disturbances compared with the usual velocities of acoustic-gravity waves for the paths under study. Such cases can be related to the transport of magneto-gravity waves. Study of the spectral composition of the AE-index disturbances and recorded maximum observable frequencies shows consistency of their spectral features in the cases of increased correlation for small time delays. It is also found that the spectral features of the AE-index disturbances coincide with the spectral features of the disturbances of the horizontal component of the geomagnetic field on ground-based magnetic stations. According to calculated dispersion curves, the frequencies of magneto-gravity waves were estimated, and they turned out to be equal to ω ≈ (1–2) ・ 10⁻⁴ Hz.     

Rotating superconductors: Ginzburg-Landau equations

Superconductors put into rotation develope a spontaneous internal magnetic field (the “London field”). In this paper Ginzburg Landau equations for order parameter, field, and current distributions for superconductors in rotation are derived. Two simple examples are discussed: the massive cylinder and the “Little and Parks geometry”: a thin film of superconducting material deposited on a cylinder of normal material. A dependence of T _c on rotational frequency is predicted. The magnitude of the effect is estimated and should be observable. Received 28 May 2001     

Dependence of Forbush-decrease magnitudes on parameters of solar eruptions

By data of the 23^rd solar cycle, it is shown that close statistical relations exist between quantitative parameters of dimmings and arcades caused by solar coronal mass ejections (CMEs), on the one hand, and magnitudes of non-recurrent Forbush-decreases of the galactic cosmic ray flux, as well as the propagation time of disturbances from the Sun to the Earth, on the other hand. Parameters of dimmings and arcades, in particular their summarized magnetic flux of the prolonged field at the photospheric level, were calculated by data of the EUV SOHO/EIT telescope in the 195 Å Received results mean that the scale, characteristics, and propagation time of interplanetary disturbances to the Earth are determined to a large degree by measurable parameters of solar eruptions and may be estimated in advance by observations of dimmings and arcades in the EUV range.     

Physics of the amplification of vortex disturbances in shear flows

The physics of the linear mechanism of the amplification of vortex disturbances in shear flows, which is due to the nonorthogonality of the eigenfunctions of the problem in the linear dynamics, is described. To obtain the clearest and simplest picture, a parallel flow with a linear velocity shear is studied, and the vortex disturbances are represented in the form of plane waves — spatial Fourier harmonics. On this level our physical approach is consonant with the nonmodal mathematical analysis of linear processes in shear flows, which has been actively cultivated in the last few years. The physics presented explains the non-monotonic growth of vortex disturbances in time at the linear stage of evolution. Moreover, being universal, the “language” employed in this work can also be used to describe the amplification of potential (acoustic) disturbances. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 7, 517–522 (10 April 1996)     

Localized pits and peaks in forbush decrease, associated with stratified structure of disturbed and undisturbed magnetic fields

Summary Forbush decrease (FD) is generally interpreted as a result of diffusion-convection of cosmic rays in a disturbed interplanetary magnetic field associated with the magnetohydrodynamic shock wave caused by solar flare. In this paper, we point out that a large number of FDs contain an isolated region or regions with pit-type time profile, in which cosmic rays are not in a diffusion-convection state but in a trapped state in undisturbed, uniform and strong magnetic field perpendicular to the solar wind. The trapped state is also characterized with a large ratio of the magnetic to ion thermal energy. The median duration time of the state is about 8 hours. About half of these states are associated with the northward (or southward) magnetic field, while the other half with the eastward (or westward) magnetic field. Flares responsible for the former state seem to be concentrated in an eastward region from about 30°W on the solar disk, while those for the latter state seem rather symmetric with respect to the centre of the solar disk. It is suggested that the trapped state is produced inside a magnetic tube of force which is not of a small scale such as that of the magnetic bubble pointed out by Klein and Burlaga, but of a large scale, having a horseshoe structure with its ends supposed to be connected to somewhere in an inner region near the Sun and with its cross-section supposed to be of a thin filament with radial and transverse dimensions of ≈0.1 a.u. and ≈1.1 a.u. at the Earth’s orbit. This belt-like tube of force is supposed to be produced on the solar surface or near the Sun and to be carried out by solar wind in a frozen state, trapping in itself low-density cosmic rays near the Sun. In addition to the pits, we point out also the existence of some peaks which are observed not only in the trapped region but also in a region of extremely disturbed magnetic field neighbouring in between two trapped regions. It is suggested that cosmic rays in the region of the latter type are supposed to be guided freely (or easily) from outer space through a path with similarly disturbed magnetic state, and therefore, they could maintain their density in the region always higher than in the neighbouring regions. Two kinds of cosmic-ray-guiding mechanism in the above can be regarded as being at opposite poles.