Formation of the disk structure and jets in the symbiotic system Z and during periods of activity in 2006–2010

We present an analysis of spectrophotometric observations of the latest cycle of activity of the symbiotic binary Z And from 2006 to 2010. We estimate the temperature of the hot component of Z And to be ≈150 000−170 000 K at minimum brightness, decreasing to ≈90 000 K at the brightness maximum. Our estimate of the electron density in the gaseous nebula is N _e = 10¹⁰−10¹² cm⁻³ in the region of formation of lines of neutral helium and N _e = 10⁶−10⁷ cm⁻³ in the region of formation of the [OIII] and [NeIII] nebular lines. A trend for the gas density derived from helium lines to increase and the gas density derived from [OIII] and [NeIII] lines to simultaneously decrease with increasing brightness of the system was observed. Our estimates show that the ratios of the theoretical and observed fluxes in the [OIII] and [NeIII] lines agree best when the O/Ne ratio is similar to its value for planetary nebulae. The model spectral energy distribution showed that, in addition to a cool component and gaseous nebula, a relatively cool pseudophotosphere (5250–11 500 K) is present in the system. The simultaneous presence of a relatively cool pseudophotosphere and high-ionization spectral lines is probably related to a disk-like structure of the pseudophotosphere. The pseudophotosphere formed very rapidly—over several weeks—during a period of increasing brightness of Z And. We infer that in 2009, as in 2006, the activity of the system was accompanied by a collimated bipolar ejection of matter (jets). In contrast to the situation in 2006, the jets were detected even before the system reached its maximum brightness. Moreover, components with velocities close to 1200 km/s disappeared at the maximum, while those with velocities close to 1800 km/s appeared.     

The phenomenon of “self-focusing” in the gaseous disk of the Galaxy

We consider perturbations in interstellar gas excited by the gravitational field of the spiral-density wave that is responsible for the Galactic arms, taking into account thermal effects. Under the conditions of fairly efficient cooling, the reaction of the gas to the perturbing field is non-trivial: the thickness of the gaseous layer is reduced in the region of the Galactic disk where the density of the gas is enhanced. We call this effect “self-focusing,” and explain it using observational results for the Galactic radio emission in the 21 cm line. Under our assumptions, we find the control parameter (δ) governing the relationship between perturbations of the thickness of the gaseous disk and the gas density in the vicinity of the Galactic equator, i.e., this parameter shows whether the correlation between these quantities is positive or negative, and provides important additional information on the thermal properties of the medium. It can be used as a diagnostic in joint studies of Galactic structure and large-scale features of the interstellar gas. Estimates for the typical Galactic parameters show that the effect of self-focusing should be clearly manifest in the Galaxy.     

A “tsunami” in the protoplanetary disk of SV Cep

The results of ~15 years of photometric observations of the UX Ori star SV Cep in the near-infrared (JHKL) are presented. They demonstrate the presence of a cyclic component with a period of ~7 years in the variations of the IR fluxes. This is clearly seen in all four IR bands, but is absent in the optical. The variation amplitude is highest in the K band: ΔK ≈ 0.68 ^m . The shape of the variations differs slightly in the transition from J to L. However, it is reproduced with good accuracy during two cycles, suggesting a periodic process is observed. If the periodic perturbations in the circumstellar disk of SV Cep are due to a companion’s orbitalmotion, the orbital semi-major axis should be ~5AU, foramass of SVCep of 2.6M _⊙. The absence of a seven-year period in the optical light curve of SV Cep means that the observed period cannot be due to variations in the circumstellar extinction. The IR brightness variations could be due to the companion’s motion along an eccentric orbit, resulting in a periodic modulation of the rate of accretion onto the star.     

Frontiers in early Earth history and primordial life——Part Ⅱ

正Following the publication of Part Ⅰ of the series on"Frontiers in early Earth history and primordial life"(Maruyama and Santosh,2017),we present the second part in this volume compiling state-of-the-art research focusing on issues related to the early evolutionary history of the Earth and life.The first paper by Imaeda and Ebisuzaki(2018)on"Single planet formation regime in the high-ionization environment:     

Three-dimensional hydrodynamical modeling of the two-component wind and accretion disk in the close binary β Lyrae

This paper continues a series of studies on three-dimensional hydrodynamical modeling of mass transfer in the binary system β Lyr. The model takes into account the stellar wind from the donor star, which outflows at a rate of , as demonstrated by radio observations. This stellar wind should appreciably influence the formation of the envelope in the binary. Computations have shown that the interaction of the matter flow from the Lagrangian point L₁ and the accretor wind leads to the formation of an optically and geometrically thick gaseous envelope around the accretor. The matter flow meets the accretor wind, spreads out, accumulates over the outer edge of the wind, and forms a geometrically thick envelope (disk). The wind flows freely at the center of the disk, over the accretor poles. Jet-like structures arise beyond the wind-propagation region, above the thick accretion disk. The matter flowing from the outer edge of the disk interacts with the donor wind, leading to the formation of a standing shock between L₁ and the outer edge of the disk, in the direction corresponding to orbital phase 0.25. This shock is able to explain the origin of the X-ray radiation from the binary β Lyr.     

The effect of lead on the activity of carbon-fixation enzymes in Potamogeton pectinatus

Lead is one of the major heavy-metal contaminants in water environments. It can exert a stress on the growth of submersed plants through changing the activities of carbon-fixation enzymes in their photosynthesis. In this work, a worldwide distributed species of submersed plants- Potamogeton pectinatus, which can survive in different water environments such as in Dianchi Lake, a severe eutrophic lake, was cultivated in improved Hoagland＇s solution and treated with different concentrations of lead. In order to realize the effect of lead on the photosynthesis of this plant, the chlorophyll contents were determined and the activities of carbon-fixation enzymes including ribulose bisphosphate carboxylase （RuBPc）, phosphoenolpyruvate carboxylase （PEPc） and carbonic anhydrase （CA） were analyzed.     

A Bright-Coloured Flower in the Field of Earth Sciences in China——in Celebration of the 70th Anniversary of the Publication of Acta Geologica Sinica

Acta Geologica Sinica (hereinafter referred to as the Acta) starting publication in 1922, is a quaterly academia periodical sponsored by the Geological Society of China (GSC). It has been one of the science and technology periodicals in China with the longest history.     

Accumulative Landforms in Valleys with Gas-Hydrothermal Occurrences (from the Example of Watercourses of Some Volcanic Massifs in the Kuril—Kamchatka Region)

Doklady Earth Sciences - The sulfur isotope anomalies ∆33S and ∆36S known today in ancient rocks exhibit common geochemical patterns reflected in the existence of a correlation like...     

Combining Robustness with Efficiency in?the?Estimation of the Variogram

In the present paper, we propose a new method for the estimation of the variogram, which combines robustness with efficiency under intrinsic stationary geostatistical processes. The method starts by using a robust estimator to obtain discrete estimates of the variogram and control atypical observations that may exist. When the number of points used in the fit of a model is the same as the number of parameters, ordinary least squares and generalized least squares are asymptotically equivalent. Therefore, the next step is to fit the variogram by ordinary least squares, using just a few discrete estimates. The procedure is then repeated several times with different subsets of points and this produces a sequence of variogram estimates. The final estimate is the median of the multiple estimates of the variogram parameters. The suggested estimator will be called multiple variograms estimator. This procedure assures a global robust estimator, which is more efficient than other robust proposals. Under the assumed dependence structure, we prove that the multiple variograms estimator is consistent and asymptotically normally distributed. A simulation study confirms that the new method has several advantages when compared with other current methods.     

Environmental Geochemistry of Fluorine in the Rock—Soil—Water System in the Karst Region of Central Guizhou Province

Systematic determination of and adsorption experiment on fluorine in the carbonate rock-soil-water system in the karst region studied in Guzhou Province,in conjunction with the mineral surface and soil chemistry data,have revealed the geochemical characteristics of F and the mechanisms of its transport and entrichment in the rock-soil-water-system of the karst region central guizhou province,Deep-seated underground waters(-100m or lower)and soil layers in the karst region of central Guizhou are characterized by high-F anomalies whereas shallow-level underground and surface waters by low contents of F(mostly lower than 05mg/L).Fluorine in soil and water in the region studied comes largely from Triassic marine strata dominated by gypsum-bearing carbonate rocks.The special adsorption and desorption of F on the surface of geothite in soil layers are the important mechanisms of its transport and enrichment in the rock-soil-water system of the karst region studied.     

The nature of metals—sediment—water interactions in freshwater bodies,with emphasis on the role of organic matter

A review with 227 references of the title subject is presented. It is divided into two main sections, viz., nature and properties of humic matter, and water—metal—sediment interactions.The first section deals with the essential properties of organic matter which occurs naturally in drainage sediments and waters. Discussion of the basic molecular structure of humic and fulvic acids is followed by some details of the chemical nature of functional groups within these structures which are important in metal-ion adsorption and complexing reactions which these materials can undergo. Information is also presented for colloidal and polyelectrolyte properties, complexation properties, and finally a summary discussion of metal-ion—humic-acid, metal-ion—fulvic-acid stability constants for both single ligand and mixed ligand systems completes the section.The second section comprises discussions of some specific aspects of interactions between metals, sediments and waters, including metal and organic speciation studies; sorption interactions between organic matter, clays and humic acids; chemical reaction between humic acids, heavy-metal minerals, clays and other silicate minerals; metal-ion adsorption—desorption studies, oxidation—reduction reactions between metal ions and humic acids; effects of sulphide ion on some of the above interactions and finally a summary of some relevant field geochemical dispersion studies.This second section describes both laboratory and field studies for each aspect.     

The Depositional Environment of the Cretaceous Kizilsu Group in Xinjiang——With a Discussion of the Lowermost Marine Horizon of the Cretaceous in the Western Tarim Basin

In this paper. it is demonstrated that there exist marine horizons in the upper part of the lower subcycleand the upper subeycle of the Kizilsu Group in Xinjiang. based on new evidence of authigenic glauconite.boron content. carbon and oxygen stablc isotopic analyses. and lithological and sedimentary features. The up-per part of the lower subeycle is the lowermost marine horizon of the Cretaceous in the western Tarim Basin,which is inferred to be of Barremian age.     

Interpretation of the light curves of “quiescent” X-ray novae in a model with a noncollisional interaction between the flow and disk. The XTE J1118+480 system

We have analyzed the orbital light curve of the X-ray nova XTE J1118+480 in a “disk + hot line” model based on three-dimensional gas-dynamical computations of gas flows in interacting binary systems. As a result, we have been able to derive reliable parameters for the system: i = 80 _?4 ⁺⁴ degrees, _MBH = 7.1 _?0.1 ^+0.5 M_⊙, M _opt = 0.39 _?0.07 ^+0.15 M_⊙.     

Main stages of tectonomagmatic activity of the Tuva–Mongolian microcontinent in the Precambrian: data on the U–Pb age of zircons

The U–Pb age of zircons from Ediacaran sandstones of the cover of the Tuva–Mongolian microcontinent and the rocks of its Early Precambrian basement (Gargan block) was analyzed by the LA–ICP–MS method. The major stages of tectonomagmatic activity of this block include the Neoarchean, Paleoproterozoic (no younger than 2 Ga), and Neoproterozoic. Comparison of the age of zircons from Ediacaran terrigenous rocks of the Tuva–Mongolian microcontinent and sandstones of the reference sections of the Ediacaran shelf of the Siberian platform undeniably indicates their independent accumulation.     

Measurement of the difference in the Earth’s gravitational potentials with the help of a transportable quantum clock

The results of the Russia’s first ground-based experiment for determination of the difference in the Earth’s gravitational potentials on the basis of the measurement of the gravitational effect of the time delay with the help of a high-stability transportable atomic clock are provided. The reference atomic clock was placed in Moscow oblast, and a transportable quantum clock with an instability of 3 × 10^–15 was placed in the Caucasus Mountains, with a difference in height of the clocks of 1804 m. The measured difference in the gravitational potentials between the positions of the two quantum clocks was (182.0 ± 3.1)10²m²s^-2 at a relative measurement error of no more than 1.7%.     

Determination and Significance of the Bluemull Blastomylonite Zone in the Northeast——East of Yell,Shetland

There is a zone of blastomylonites containing hornblende gneisses of Lewisian Inliertype in the northeast-east of Yell,Shetland.This zone with a north—northwesterlytrend consists of blastomylonised hornblende-banded gneiss,hornblende-feldspar gneissand mica-felsie-gneiss with lenses of hornblende gneiss.It is indicated that theblastomylonite zone is actually a ductile shear zone and the sense of shear is dextral.This contributes to understanding the details of tectonic evolution in this area,and thiszone is probably a part of tectonic system of the British Caledonides.     

Thermoluminescence and the shock and reheating history of meteorites—III: The shergottites

The thermoluminescence (TL) sensitivities of the four shergottites are extremely low and display a 10-fold range (values are 0.15 to 1.8, where Dhajala = 1000), with the TL sensitivity decreasing with increasing peak temperature (from about 140 to 180°C) and peak width (from about 100 to 150°C). A mineral separation experiment indicates that the mineral producing the TL is associated with the maskelynite, presumably nanogram per gram quantities of crystalline feldspar are present in the maskelynite. Samples of Shergotty, Allan Hills A77005 and Elephant Moraine A79001 were annealed at 400–900°C for 24–98 h. For Shergotty, the peak increased in width and moved to higher temperatures in the glow-curve, while for Allan Hills A77005 and Elephant Moraine A79001, whose TL peaks were already broad and at high temperatures, remained unchanged. All samples showed a significant increase in TL sensitivity when annealed at >600–700°C. Apparently, the feldspar is present in varying proportions of high to low-temperature form and in amounts which vary from meteorite to meteorite. We conclude that the shergottites underwent post-shock recrystallization at a variety of cooling rates and that the order of increasing cooling rate was Shergotty, Allan Hills A77005, Zagami and Elephant Moraine A79001. The presence of a high-temperature phase implies peak post-shock cooling temperatures >600°C and that the size of the ejecta was <10 m. Current theories are well able to explain the ejection of such small objects from Mars.     

Mineralogical properties of the suspended matter in the Yangtze River: Correlations with seasonality

Erosion products in stream water occur in the form of either dissolved species or solid particles (suspension). The suspended material not only acts as a carrier but also plays an important role in the circulation process of pollutants. Knowledge on the n…