Formation and evolution of planets

Hydrodynamical calculations are becoming increasingly successful at understanding the shapes and kinematics of planetary nebulae (PNs). The most successful models are two-dimensional interacting stellar wind models for which the PN nucleus is assumed to originally expel much or most of its mass in an equatorial waistband. The physics of the ensuing evolution seems to be explained nicely by a combination of hydrodynamics coupled with time-dependent stellar ionization and energy loss through nebular radiation. Recent radiation gas dynamic calculations are shown to yield excellent agreement with data.     

Studies of Giant Pulses from the Pulsar B0301+19 (J0304+1932) at 111 MHz

Astronomy Reports - The results of observations of the pulsar B0301+19 (J0304+1932) carried out on the Large Scanning Antenna of the Pushchino Radio Astronomy Observatory at 111 MHz during...     

Native gold and ore mineral inclusions in detrital zircon and quartz from the early precambrian quartzites and quartz gravelstones of the Karelian Craton

The study of solid mineral inclusions in detrital hydrothermal and hydrothermally altered zircons and quartz from Archaean and Palaeoproterozoic (Sumian and Jatulian) terrigenous quartz-rich clastic rocks of the Karelian Craton on a VEGA II LSH-TESKAN microanalyzer has revealed, for the first time, micron-sized native gold inclusions and associated syngenetic inclusions of ore minerals, such as galena, sphalerite, pyrite, chalcopyrite, molybdenite, molybdoscheelite, native bismuth and cerussite, as well as barite and complex hydroaluminophosphates of the goyacite-gorceixite-florencite-plumbogummite group. This mineral association in detrital material could indicate the ore-forming nature of its quartz vein source. These data, together with the earlier results of the local isotopic (SHRIMP-II and LA-ICP-MS) dating of these and similar heterogeneous detrital zircons, are indicative of several hydrothermal events, dated at 3.3, 3.15?C2.9 and 2.76?C2.65 Ga, which occurred in the region in Archaean time. The two latter ages are consistent with the time of formation of quartz vein ore systems with some of which gold ore-forming processes were associated.     

The Pokrovskoe gold-silver deposit (Amur Region): Geological settings, formation factors, and ore mineralogy

The Pokrovskoe gold-silver deposit is explored by drill holes. Its gently dipping orebodies (lodes) revealed by core sampling are quarry mined. It is considered that they also consist of gently dipping quartz veins and vein-stringer zones. The performed investigation of the terraces in the exploited quarries made it possible to correct the available present-day concepts. It is shown that their structure is dominated by steeply dipping veins and vein-stringer zones. They are characterized by the northeastern strike in the central part of the deposit and its western flank and the mostly northwestern one in its eastern part. An important role in the formation and distribution of the orebodies belongs to various geological screens poorly permeable for fluids. The main factors responsible for the ore localization in screened hydrogeological systems are revealed with the assessment of the thermal impact of a dacite sill on the formation of the ore-hosting cavities and ore deposition. The electron microscope investigation of the ores substantially widened the spectrum of ore minerals previously unknown in this deposit, including gold-bearing varieties (copper gold and its complex intermetallic compounds). Based on the dominant micrometer sizes of all the ore minerals and their dispersion within the quartz matrix, it is inferred that the deposition of productive ores occurred in nonequilibrium environments.     

METEOR-L Device on the Lunar Orbital Vehicle Luna-26: Space Dust Detector

Solar System Research - The ionization-type cosmic dust detector METEOR-L is being developed for the lunar orbiter Luna-26 and is designed to study the distribution of meteoric bodies in space by...     

TERMO-LR Experiment on the Luna-27 Lander: Study of Thermophysical,Physicomechanical, and Electromagnetic Properties of the Lunar Soil

Solar System Research - The device is being developed for the TERMO-LR experiment on the Luna-27 lunar lander; it is intended for contact geophysical measurements of various properties of the lunar...     

Effect of fluid column dynamics on longitudinal vibrations of an ultra deepwater riser covered by an orifice plug

The paper studies longitudinal vibrations of an ultra-deepwater drilling riser whose bottom end is disconnected from the sea floor and covered by a plug (a blind one or the one with a hole). An elastic shell is used as a model of a riser pipe. The fluid column motion in the riser is described by the Navier–Stokes equation for a compressible fluid. Losses of fluid pressure during its flowing through a hole in the plug are taken into account. Solution of the riser equations is carried out in the frequency domain. Analysis of the effect which the riser length, wave period and height, and the plug-hole diameter on the amplitude of the riser's tension vibrations is conducted. A riser manufactured of strong aluminium alloys, some of prospective materials for ultra deepwater drilling, was considered as a prototype. It has been shown that risers 2000–4000 m long, plug-hole, and a riser 6000 m long with plug-hole of 0.087 m in diameter can withstand wave height of >15 m throughout the frequency range.