Circumsolar Stellar Streams and Meteors in the Earth Atmosphere

Astronomy Reports - On the basis of the Gaia data, we analyze the formation pattern of peripherical structures of planetary systems, the elements of which are dust, asteroids, comets, and unbound...     

Destruction of Galaxies as a Cause of the Appearance of Stellar Streams

Astronomy Reports - The interaction of galaxies in clusters with the intergalactic gaseous medium and other galaxies is considered. The causes for the appearance of gaseous and stellar...     

Spectroscopy of Globular Clusters in the Spheroidal Dwarf Galaxy IKN

Astronomy Reports - Moderate resolution spectra of four globular clusters in the dwarf spheroidal galaxy IKN obtained with the 6-m telescope of the Special Astrophysical Observatory have been used...     

Study of Cooling Processes during the Decay Phase of Solar and Stellar Flares

Astronomy Reports - The work is devoted to the study of cooling processes and energy loss during the decay phase of flare. During this phase, various wave processes can occur simultaneously with...     

Kinematics of OB Associations and the First Data from the Gaia Satellite

The first data release from the Gaia mission (Gaia DR1) is used to study kinematics of OB associations. The mean velocity dispersion in 18 OB associations containing at least 10 stars with proper motions from the TGAS catalog is 3.9 km/s. The contribution of binary systems to the velocity dispersions in OB associations is, on average, 1.2 km/s. Expansion of the OB associations Per OB1 and Car OB1 is observed. This paper is based on a presentation made at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017).

     

On the Status of the Star Schulte 12 in the Association Cyg OB2

Astronomy Reports - High-resolution spectra of the LBV candidate Schulte 12 in the Cyg OB2 association were obtained at the 6-m BTA telescope with the NES echelle spectrograph on the arbitrary...     

Contribution of Binary Stars to the Velocity Dispersion inside OB Associations with Gaia DR2 Data

Astronomy Reports - We estimated the contribution of binary systems to the velocity dispersion inside OB-associations derived from Gaia DR2 proper motions. The maximum contribution to the velocity...     

Galaxy Rotation Parameters from OB2 Stars with Proper Motions and Parallaxes from the Gaia EDR3 Catalog

Astronomy Reports - We have analyzed the kinematics of OB2 stars with proper motions and parallaxes selected by Xu et al. from the Gaia EDR3 catalog. The relative parallax errors for all the stars...     

Stages and Formation Conditions of Productive Mineral Associations of the Dalnegorsk Borosilicate Deposit,Sikhote Alin

Geology of Ore Deposits - A special investigation of fluid inclusions and geochemical and isotopic studies of their typomorphic features were carried out for danburite and datolite from skarn...     

Anatomy of a transgressive lag: Panther Tongue Sandstone, Star Point Formation, central Utah

Abstract The Panther Tongue of the Star Point Formation in central Utah contains a variety of transgressive lag deposits that, when mapped regionally, show a sensitive dependence upon pre‐existing topography of the palaeoshoreline. The Panther Tongue consists of a coarsening‐upward sandstone wedge that prograded into the Western Interior Seaway during Late Cretaceous (Santonian) time. High‐resolution sequence stratigraphic analysis revealed that this member was deposited during the long‐distance (>50 km) regression and transgression of a delta into shallow‐marine environments, containing basal highstand, forced regression, lowstand and transgressive systems tracts. Based on grain size, clast composition, lateral extent and stratigraphic position, the coarse sandstones on top of the Panther Tongue were classified into four types: (1) simple; (2) dispersed; (3) oxidized; and (4) local lags. The simple lag is composed of dark grey coarse sandstone with oyster fragments and shark teeth. This lag is typically extensively bioturbated and massive. Laminated and cross‐bedded units are also common. This type of coarse sandstone is interpreted as a typical transgressive lag. The dispersed lag differs in that it contains abundant mud and commonly occurs as multiple beds in thick intervals of muddy sandstone. Mixing of bay/estuarine and shallow ‐ marine mud with simple lag sand may be responsible for deposition of this type of coarse sandstone. The oxidized lag is distinctive in its reddish colour with extensive bioturbation and is commonly overlain by a simple lag. The local lag is composed of thin‐bedded, dark grey, coarse sandstone, occurring locally between the mouth bar and distributary channel. The variation in types, grain size and bed thickness of the coarse‐grained lags was mainly controlled by antecedent topography as suggested by immediately underlying lithofacies. Relatively thick (≈30 cm) simple lags are present on top of mouth‐bar sandstones, whereas dispersed lags are common on top of the distributary channel sandstone and in bay/estuarine and shallow‐marine mudstones. Erosion of topographic highs (mouth bar) resulted in relatively thick accumulation of simple lags. In topographic low areas such as distributary channel, estuary, bay and shallow‐marine environments, fine‐grained muddy sands that were eroded from the nearby topographic highs were redeposited. Intermittent storm waves transported coarse sands both landward and seaward, forming a dispersed lag. The net effect was reworking of local topographic relief during overall transgression, forming an apparently planar transgressive surface of erosion.     

Facies Associations and Discontinuous Surfaces in the Syringothyris Limestone Formation of Tethyan Margin of Gondwana,Kashmir

The early Carboniferous sedimentation of the Tethyan Margin of Gondwana in the Kashmir Himalaya represents alternating siliciclastic - carbonate succession consisting of distinct stratigraphic sequences which are bounded by discontinuities. The discontinuities in the sedimentation are related to environmental changes in the form of subaerial exposure, subaqueous erosion, subaqueous omission or changes in texture and facies. These distinct surface zones or time significant boundaries can be correlated across the depositional platform. Low stand, high stand and transgressive sedimentation units in the lower and middle parts of early Carboniferous Syringothyris Limestone Formation in Banihal area have been recognised. This is explained by superposition of high frequency and low amplitude sea level fluctuations on a large-scale trend under greenhouse conditions during the early Carboniferous period. The facies associations present in the early Carboniferous succession of the Himalaya broadly represent intertidal (peritidal), shallow subtidal, deeper subtidal, off-shore-slope and deeper environments. Discontinuities that are interpreted as progradational, retrogradational and aggradational phases of sedimentation bound these facies associations. This formation represents continental margin depositional setting which is authenticated by deposition of siliciclastic sediments. This marginal depositional setting is greatly affected by numerous dynamic processes including tectonic and other active sea as well as continental processes. The records of all those processes in this formation reflect the eustatic changes in sea level. These periodic eustatic changes have generated the various discontinuities, stratigraphic sequences or systems tracts. Overall it appears that interplay of many processes such as sediment supply, thermal and tectonic activity, eustatic and climatic changes in the Kashmir Tethyan depositional basin generated these distinct depositional sequences during the early Carboniferous period.     

The Simulation of Orbit Decay of Double Neutron Star System PSR J1906+0746 by the Gravitational Wave Radiation

With the discovery of the double neutron star (DNS) merger event GW170817 by LIGO, DNS systems have become one of the important candidates for gravitational wave (GW) observation. There are 19 DNS systems that have been discovered, and PSR J1906+0746 is the youngest DNS system with the age of about 0.1 Myrs. We simulate its orbital decay over its entire life by the GW radiation from the initial stage to the coalescence. For the DNS PSR J1906+0746, we obtain its initial orbital period of 3.99 hrs (3.98 hrs at present) with the nearly circular orbit, and the merger age of 3.18 × 10⁸ yr. At the last minute of coalescence, corresponding to the orbital radius change from 335 to 30 km, we present the GW frequency to be 30 and 1122 Hz, respectively. As a comparison, with the GW frequency from 45 to 450 Hz, the orbital radii of the source GW170817 correspond to 163 and 57 km, respectively.

     

百色盆地那读组层序分析与生储盖组合

通过野外露头、钻井岩心、测井曲线和地震资料的综合分析,在识别出 4类不同成因类型和规模的层序界面基础上,将百色盆地那读组划分为 1个超长期、5个长期和 16个中期基准面旋回层序。并详细地讨论了层序与生储盖组合的关系,指出生储盖组合特征与长期基准面旋回关系最为密切,有利储层发育位置主要出现在长期基准面上升半旋回的早中期和下降半旋回的中晚期,转换面附近则是烃源岩和盖层的发育位置;各长期旋回层序的生储盖组合具不同特征,明显受基准面升降幅度、频率及其所影响的相组合、可容纳空间和A/S值变化控制;按生储盖组合在垂向和纵向上的配置关系,可划分为上生下储、下生上储、侧向运移等 3种基本组合类型。     

Evolution of OH and H2O Maser Emission in the Active Star Formation Region NGC 2071

Astronomy Reports - We present the observation results of the star forming region NGC 2071 in the 1.35-cm H2O line and 18-cm OH lines obtained with the 22-m radio telescope in Pushchino (Russia)...     

做好传统地质、建好绿水青山——在中国地质学会第十二次全国会员代表大会上的讲话

正各位代表,同志们:下午好!在刚刚结束的全体理事大会上,大家选举我担任中国地质学会第40届理事会理事长,我感到非常荣幸,也深感责任重大。在此,我代表新当选的第40届理事会对大家的信任表示衷心的感谢!我将认真履行理事长的职责,和全体常务理事一道,在中国科协和国土资源部的领导下,在历届理事会工作的基础上,团结带领全体理事,认真学习宣传贯彻党的十九大精神,以习近平新时代中国特色社会主义思想为指     

Streaming motions of molecular clouds, ionized hydrogen, and OB stars in the Cygnus arm

The radial velocity fields of molecular clouds, OB stars, and ionized hydrogen in the Cygnus arm (l ～ 72°–8°) are analyzed. A gradientΔV _LSR/Δlin the mean line-of-sight velocities of molecular clouds and ionized hydrogen due to differential Galactic rotation is detected, and two groups of physically and genetically associated objects moving with different line-of-sight velocities are identified. One of the two molecular-cloud complexes (l～77.3°–80°) is located within 1 kpc of the Sun, closer to the inner edge of the arm, whereas the other complex (l～78.5°–85°) lies 1–1.5 kpc from the Sun and is farther from the inner edge of the arm. The residual azimuthal velocities of the objects in both groups are analyzed. The residual azimuthal velocities of the first molecular-cloud complex are directed opposite to the Galactic rotation (V _Θ ～ ?7 km/s), while those of the second complex are near zero or in the direction of Galactic rotation, independent of the distance to the complex (V _Θ ≥ 1 km/s). Like the molecular clouds, stars of the Cygnus arm form two kinematic groups with similar azimuthal velocities. On the whole, the mean azimuthal velocities V _Θ for the ionized hydrogen averaged over large areas agree with the velocities of either the first or second molecular-cloud complex. In terms of density-wave theory, the observed differences between the magnitudes and directions of the azimuthal velocities of the kinematic groups considered could be due to their different locations within the arm.     

Collapse,Connectivity, and Galaxy Populations in Supercluster Cocoons: the Case of A2142

Astronomy Reports - The largest galaxy systems in the cosmic web are superclusters, overdensity regions of galaxies, groups, clusters, and filaments. Low-density regions around superclusters are...     

Formation of mud clast breccias and the process of sedimentary autobrecciation in the hominin-bearing (Homo naledi) Rising Star Cave system,South Africa

Unconsolidated mud clast breccia facies in the hominin-bearing (Homo naledi) Rising Star Cave, Cradle of Humankind, South Africa, are interpreted to have formed through a process termed sedimentary autobrecciation in this study. This process, by which most of the angular mud clast breccia deposits are thought to have formed autochthonously to para-autochthonously via a combination of erosion, desiccation, diagenesis and microbial alteration of laminated mud deposits, is thought to have taken place under relatively dry (i.e. non-flooded) conditions inside the cave. Subsequently, gravitational slumping and collapse was the dominant mechanism that produced the mud clast breccia deposits, which commonly accumulate into debris aprons. The mud clast breccia is typically associated with (micro) mammal fossils and is a common facies throughout the cave system, occurring in lithified and unlithified form. This facies has not been described from other cave localities in the Cradle of Humankind. Additionally, sedimentary autobrecciation took place during the deposition of some of the fossils within the Rising Star Cave, including the abundant Homo naledi skeletal remains found in the Dinaledi Subsystem. Reworking of the mud clast breccia deposits occurs in some chambers as they slump towards floor drains, resulting in the repositioning of fossils embedded in the breccias as evidenced by cross-cutting manganese staining lines on some Homo naledi fossil remains. The formation of the unlithified mud clast breccia deposits is a slow process, with first order formation rates estimated to be ca 8 × 10⁻⁴ mm year⁻¹. The slow formation of the unlithified mud clast breccia facies sediments and lack of laminated mud facies within these deposits, indicates that conditions in the Dinaledi Chamber were probably stable and dry for at least the last ca 300 ka, meaning that this study excludes Homo naledi being actively transported by fluvial mechanisms during the time their remains entered the cave.     

贵州紫云—罗甸县丛里地下河岩溶发育特征

贵州省紫云—罗甸县丛里地下河系统流域面积211km²,系统内可溶的碳酸盐岩石在平面上广泛分布,空间上厚大产出。经多期地质构造迭加,岩石多数地段较为破碎,使地表及地下岩溶化程度较高。新构造运动不断使地壳抬升,排泄基准面的不断下切,形成系统内一个非常复杂的多层次的岩溶管道系统。由于岩溶发育的差异和不均匀性,构成了不同的地貌形态及地下暗河埋藏深度的差异。地下岩溶管道系统与表层的岩溶个体的交融所形成的可特景观,在地质研究、旅游资源开发上有重要意义。     

广东三个翡翠产业集群形成及发展机理初探

通过对广东阳美、四会、平洲三个翡翠产业集群发展状况的研究,揭示该区域翡翠产业的形成及发展机理。研究结果认为,可以将该区域翡翠产业的发展过程分为两个阶段,并且不同的阶段有不同的主导因素、发展方式和发展动力。初步形成阶段的主导因素是政府政策和当地的经济能人,发展方式是模仿和技术扩散,发展动力是攀比效应和信息优势;快速发展阶段的主导因素是市场规律和集群引起的外部效应,发展方式是与集群相关的产业的快速集聚,发展动力是技术创新。