Solar structures related to coronal holes

The nature of structures detected recently on the Sun in soft X rays by I.F. Nikulin (Sternberg Astronomical Institute) and called by him “partings” is discussed. It is shown that these structures are sign-reversal lines for the normal component of the curvature vector of the magnetic lines. Equations describing these lines are derived and models of the corresponding fields calculated.     

Periodic processes and plasma motions in solar coronal holes

Episodic observations of coronal holes were carried out simultaneously in several spectral lines during the 2002–2005 observational seasons. An analysis of eighteen time series is used to obtain the amplitude—spectral properties of oscillatory wave motions of the solar plasma at the bases of coronal holes. It is found that the amplitudes of the 5-min and 3-min line-of-sight velocity oscillations increase in coronal holes. Low-frequency (1–2 mHz) oscillations are concentrated at the boundaries of the chromospheric network, while the 3-mHz and 5-mHz oscillations dominate in the network cells. Clear indications of propagating waves have been found at the bases of coronal holes. The 3 mHz phase velocities are 45 ± 5 km/s and 80–100 km/s for the equatorial and polar coronal holes, respectively.     

Quasi-periodic line-of-sight velocity variations at the bases of polar coronal holes

Spatial and temporal variations in the line-of-sight velocities and brightnesses measured in the Hα and FeI 6564 Å Hβ and FeI 4864 Å NiI 4857 Å lines at the bases of polar coronal holes are analyzed. Time series with durations of 43–120 min were recorded using a CCD strip (3700 pixels 200×7 µm in size) and a CCD array (256×1024 pixels 24 µm in size). Quasi-stationary upward flows (with radial velocities reaching 3 km/s in the photosphere and 12–15 km/s in the chromosphere) were observed near dark points at the boundaries of the chromospheric network. The acoustic 3-min and 5-min oscillations are amplified in the coronal hole, and reach 1 km/s in the photosphere and 3–4 km/s in the chromosphere. The spectra of fluctuations of the line-of-sight velocity exhibit significant maxima at low frequencies, clustering near 0.4, 0.75, and 1 mHz.     

Relationship between the contrast of coronal holes and parameters of the solar wind streams

It is shown that the contrast of coronal holes (CH) determines the speed of the solar wind streams to the same extent as their area does. We analyzed more than 400 images obtained in the λ284 Å channel. The time interval under examination covers about 1500 days in the declining phase of cycle 23 (from 2002 to 2006). We considered all coronal holes recorded during that interval in the absence of coronal mass ejections (CME). Comparison was also made with some other parameters of the solar wind (e.g., density, temperature, and magnetic field). A fairly high correlation (0.70–0.89) was obtained with the velocity, especially during the periods of moderate activity, which makes this method useful for everyday forecast. The ratio of CH brightness to the mean brightness of the disk in the λ284 Å channel is about 25%.     

Suprathermal ions in solar-wind outflows from coronal holes at 1 AU

The energy spectra and relative abundances of ³He, ⁴He, C, O, and Fe ions with energies of ~0.04–2 MeV/nucleon are studied using data from the ULEIS instrument on board the ACE spacecraft obtained during quiescent periods in 2006–2012. During the unique, prolonged minimum between cycles 23 and 24, 35 quiescent periods were distnguished, during which solar-wind flows from near-equatorial coronal holes (CHs) were detected. It is shown that the C/O and Fe/O ratios for suprathermal ions correspond to the relative abundances of the corresponding thermal ions in the fast and slow (Maxwellian) solar wind (SWICS/ACE), while the ⁴He/O ratio exceeds the corresponding ratio in the solar wind by a factor of two. The intensities of the ³He, ⁴He, C, O, and Fe suprathermal ions in outflows from CHs grow with the speed of the solar wind. This indicates that, in periods ofminimumsolar activity, suprathermal ions from CHs represent a high-temperature “tail” of the solar wind. An additional flux of suprathermal helium ions may also be contributed by other external sources.     

The collapse of matter and the formation of black holes. Conceptual aspects

We present a comparative study of the original metric of Schwarzschild and the metric introduced by Hilbert. The properties of these metrics, as well as the Tolman metric for collapsing dust, are analyzed.     

Blast-wave and piston shocks connected with the formation and propagation of a coronal mass ejection

The solar coronal mass ejection observed on November 3, 2010 is analyzed using AIA/SDO data (images in the 193 and 211 Å channels) and white-corona images obtained with the SOHO LASCO C2 and C3 coronographs. We have succeeded in revealing both piston and blast-wave shocks attributed to the formation and propagation of a coronal mass ejection. Both of these types of shocks could be responsible for type II radio bursts propagating in front of each shock.     

Early formation of galaxies induced by clusters of black holes

A model for the formation of supermassive black holes at the center of a cluster of primordial black holes is developed. It is assumed that ～10^?3 of the mass of the Universe consists of compact clusters of primordial black holes that arose as a result of phase transitions in the early Universe. These clusters also serve as centers for the condensation of dark matter. The formation of protogalaxies with masses of the order of 2 × 10⁸ M _⊙ at redshift z = 15 containing clusters of black holes is investigated. The nuclei of these protogalaxies contain central black holes with masses ～10⁵ M _⊙, and the protogalaxies themselves resemble dwarf spherical galaxies with their maximum density at their centers. Subsequent merging of these induced protogalaxies with ordinary halos of dark matter leads to the standard picture for the formation of the large-scale structure of the Universe. The merging of the primordial black holes leads to the formation of supermassive black holes in galactic nuclei and produces the observed correlation between the mass of the central black hole and the bulge velocity dispersion.     

The role of rising magnetic tubes in the formation of impulsive coronal mass ejections

Two impulsive limb coronal mass ejections (CMEs), one of which was accompanied by an active prominence and the other by a flare, are analyzed using AIA/SDO solar data. The analysis leads to the conclusion that, in both cases, the sources of the CME formation were magnetic tubes rising from beneath the photosphere at high velocity. One or more arch structures can be located in the path of the magnetic tube, which it influences and drags along with it. The arch structures may then participate in the formation of the future CME, whose main basis is the magnetic tube itself.     

Physical differences between the initial phase of the formation of two types of coronal mass ejections

Physical differences in the formation of “gradual” and “impulsive” coronal mass ejections (CMEs) at heights of h < 0.2 R _⊙ just before and during the initial phase of their motion are studied using AIA/SDO ultraviolet data (h is the altitude above the solar surface and R _⊙ is the solar radius). The basic structure of a gradual CME is a magnetic rope located in the corona. During an hour or more preceding the initial phase, the magnetic rope demonstrates an increase in brightness and transverse size, first of the low, inner elements of the rope and then of elements in its outer envelope most distant from the Sun. The rope remains motionless during this time. The initial phase of a gradual CME begins from the motion of the magnetic rope’s outer envelope, which further becomes the basis for the CME frontal structure. At this stage, the inner low elements of the rope remain almost motionless. The initial phase of an impulsive CME begins with the appearance near the photosphere of a cavity moving away from the Sun; the dynamics of this cavity probably correspond to a magnetic tube filled with cool plasma rising from beneath the photosphere. This magnetic tube collides with and drags arch structures, which initially block the tube’s motion. These arch structures contribute to the CME formation, although the magnetic tube itself forms the basis of the CME.     

Global complexes of activity

A new concept of “Global Complexes of Activity” on the Sun is presented, which brings together objects associated with both global and local fields in a single framework. Activity complexes have traditionally been identified purely from observations of active regions. We show here that a global complex also includes coronal holes and active regions. Our analysis is based on a large dataset on magnetic fields on various scales, SOHO/MDI observations of active regions and magnetic fields, and UV observations of coronal holes. It is shown that the evolution of coronal holes and active regions are parts of a single process. The relationships between the fields on different scales during the generation of the cycle is discussed.     

The formation of a perturbed zone and shock wave excited by a coronal mass ejection

The existence of perturbed zones ahead of coronal mass ejections (CMEs) has been confirmed, and their evolution with increasing CME velocity studied. At CME velocities that are close to or higher than the local Alfvén velocity, a discontinuity forms in the plasma density distribution ahead of the perturbed zone, which can be interpreted as a shock. Estimates testify that, at distances from the solar center of R < (15–20) R _⊙, the width of the observed shock front is probably of the order of the mean free path for proton-proton collisions.     

Polychronous formation of mantle complexes in ophiolites

The paper presents new determinations of the U-Pb zircon age of high-Al chromitite from dunite of the mantle section of the Voikar-Synya massif at the Kershor site in the boundary zone with rocks of the dunite-wehrlite-clinopyroxenite complex. The high-Cr chromitite from dunite in the central part of the same massif contains zircon dated at ca. 0.6 Ga [10]. It is suggested that Paleoproterozoic (2.0?1.9 Ga) zircons from chromitites of the mantle section near the petrological Moho boundary were formed in the course of partial melting of peridotites and/or their interaction with migrating MORB-type melts. The occurrence of Vendian and Paleoproterozoic zircons in chromitites from different parts of the mantle section, as well as previously published petrological, geochemical, and geological data [2, 11, 22] allow us to suggest a complex multistage evolution of the mantle section in ophiolites. The arguments stated below show that chromitites and host dunites could have been formed at different times and were probably related to different processes. Thus, not only various complexes of the pre-Paleozoic oceanic crust reworked in the suprasubduction setting differ in age, but also the mantle rock of similar petrography, vary in the time of their formation.     

Levels of coronal and chromospheric activity in late-type stars and various types of dynamo waves

We analyze the X-ray emission and chromospheric activity of late-type F, G, and K stars studied in the framework of the HK project. More powerful coronas are possessed by stars displaying irregular variations of their chromospheric emission, while stars with cyclic activity are characterized by comparatively modest X-ray luminosities and ratios of the X-ray to bolometric luminosity L _X/L _bol. This indicates that the nature of processes associated with magnetic-field amplification in the convective envelope changes appreciably in the transition from small to large dynamo numbers, directly affecting the character of the (α-Ω) dynamo. Due to the strong dependence of both the dynamo number and the Rossby number on the speed of axial rotation, earlier correlations found between various activity parameters and the Rossby number are consistent with our conclusions. Our analysis makes it possible to draw the first firm conclusions about the place of solar activity among analogous processes developing in active late-type stars.     

Regularities in the formation and evolution of volcanosedimentary complexes in the Early Precambrian

The main objective of this work was to define directions and principal features of the evolution of volcanism and sedimentation in Early Precambrian active volcanic zones. Analysis of reconstructed type sections of intensely metamorphosed and greenstone (sedimentary-volcanic) complexes revealed a general similarity of their structure and universal presence of two principal (contrast and differentiated) volcanic associations that replace each other from the bottom to top (Lazur, 2006). Volcanic complexes are crowned with significantly sedimentary sequences and the manifestation of bimodal (basalt-rhyolite) or acid (dacite-rhyolite) volcanism (Luchitskii et al., 1982). Our work is based on specific rock complexes, for which the primary nature of intensely metamorphosed Early Precambrian rocks has been reconstructed by geological, mineralogical, geochemical, and other methods (Lazur, 1986; Rosen et al., 2005).     

Effects of coronal mass ejections on distant coronal streamers

The effects of a large coronal mass ejection (CME) on a solar coronal streamer located roughly 90° from the main direction of the CME propagation observed on January 2, 2012 by the SOHO/LASCO coronograph are analyzed. Radial coronal streamers undergo some bending when CMEs pass through the corona, even at large angular distances from the streamers. The phenomenon resembles a bending wave traveling along the streamer. Some researchers interpret these phenomena as the effects of traveling shocks generated by rapid CMEs, while others suggest they are waves excited inside the streamers by external impacts. The analysis presented here did not find convincing arguments in favor of either of these interpretations. It is concluded that the streamer behavior results from the effect of the magnetic field of a moving magnetic flux rope associated with the coronal ejection. The motion of the large-scale magnetic flux rope away from the Sun changes the surrounding magnetic field lines in the corona, and these changes resemble the half-period of a wave running along the streamer.     

Early formation of (super)massive black holes and gravitational waves from their coalescence

Astronomical observations of last few years have presented a surprising evidence that the Universe at redshift of order 10 is densely populated by supermassive black holes (quasars), supernovae, and contains very large amount of dust. All these data are in conflict with the canonical theory of quasar and supernova formation. A model is discussed which in a simple and natural way solves all these problem. In addition it explains an existence of supermassive black holes in each large galaxy and even in small ones. An inverted picture of galaxy formation is suggested when primordial black holes serve as seeds of galaxy formation. Simultaneously the origin and properties of black hole binaries, sources of gravitational waves registered by LIGO are explained. As a by-product the model may lead to abundant cosmological antimatter even in the Galaxy.     

Ballooning instability and oscillations of coronal loops

The excitation of the ballooning instability by the eigenoscillations of coronal loops is analyzed using the energy method. The second variation of the potential energy for the case of a plasma—plasma boundary is obtained via the linearized ideal MHD equations. It is shown that the eigenmodes of a magnetic tube and of a toroidal coronal loop coincide in a first approximation. The bending oscillations of the loops are able to excite the ballooning instability when β ? 1. The effects of the instability in solar coronal loops are discussed.     

Solar magnetic fields and the intensity of the green coronal line

Synoptic maps of the intensity of the λ530.5 nm FeXIV green coronal line and maps of computed coronal magnetic fields for the period 1977–2001 are compared. For quantitative comparisons, the correlation coefficients r for the correlation between these two parameters at corresponding points of the synoptic maps are calculated. This coefficient exhibits cyclic variations in the spot-formation zone, ±30° and the zone above 30° and is in antiphase in these two zones. In the low-latitude zone, the correlation coefficient is always positive, reaches its maximum at activity minimum, and strongly decreases by activity maximum. Above 30°, r reaches maximum positive values at activity maximum and then gradually decreases, passing through zero near the beginning of the phase of activity minimum and becoming negative during this phase. A Fourier analysis of r as a function of time reveals a wavelike variation with a period close to 1.3 yr (known also from helioseismological data for the tachoclinic region of magnetic-field generation), as well as a pronounced wave with a period of about 5 yr. The latitude dependence of r seems to be related to variations in the contributions from local, large-scale, and global fields. Our analysis suggests an approach to studying the complex problem of mechanisms for coronal heating.