Conservative two-body problem with variable masses

We consider the conservative two-body problem with a constant total mass, but with variable individual masses. The problem is shown to be completely integrable for any mass variation law. The Keplerian motion known for the classical two-body problem with constant masses remains valid for the relative motion of the bodies. The absolute motions of the bodies depend on the center-of-mass motion. Hitherto unknown quadratures that depend on the mass variation law were derived for the integrals of motion of the center of mass. We consider some of the laws that are of interest in studying the motion of close binary stars with mass transfer.     

Close binary systems in star-forming regions: EQ Ori in the Ori I association

Photoelectric (UBVR) observations of the eclipsing variable EQ Ori are presented. The ephemerides of primary minima are refined, and the range of the star’s light variations is determined. All light curves are solved by Lavrov’s direct method, and highly accurate photometric orbital elements are obtained for the system. The magnitudes and colors of each component are calculated and analyzed in two-color (U-B)-(B-V) and (U-B)-(V-R) diagrams. The system’s primary component is classified as a metallic-line Am star. The absolute parameters of the components are estimated, and the binary is classified as a detached system with a subgiant: A0 V and K2 IV. EQ Ori has a faint physical companion, which causes the epochs of primary minimum to be systematically displaced with a period of about 30 years. The expected parameters of the distant companion are estimated. The system’s components are at a pre-ZAMS evolutionary stage, with their age being 2×10⁶ years. EQ Ori is thought to be a member of the Ori I association.     

A near-infrared survey of IRAS sources in the South Galactic Cap

The paper describes the JHK colours of late-type stars which were investigated as part of a survey of South Galactic Cap (b < -30°) IRAS sources selected on the basis of their 12/25µm flux ratios as high mass-loss candidates. Near-infrared two-colour diagrams provide an effective technique for distinguishing between various groups of late-type stars. Such diagrams are also useful in indicating which stars are likely to be peculiar and worthy of more detailed study. The late-type stars isolated by this survey comprise: 61 Mira variables (3 of which are carbon stars with very thick shells), 3 young stellar objects, 4 interacting binaries, 2 semi-regular carbon variables and 154 oxygen-rich giants.     

The Forming Conditions of and Ore-searching Direction for B, Mg,Pb, Zn and Au Deposits in the Liaoji Proterozoic Rift

The Proterozoic was the first of severa1 impor-tant transitional periods in the earth's evolutionaryhistory. Linear .rifts over1apped on the b4se ofArchean granite -- greenstone and high -- grade gneissregimes. Along with the formation and evolution ofthe…     

Minimum on the light curve of the classical symbiotic star AS 338 in 1999

We present our UBVRI photometry and spectroscopy of AS 338 performed in 1999–2000. Another eclipse of the hot component in this symbiotic binary system, the deepest one ever observed, occurred in September 1999. The U brightness declined by ～2^m, the Hβflux decreased by a factor of ～2.3, and the [O III]γ5007 flux did not change. The hot component is eclipsed at orbital phases ?≈0.045–0.057. The U-B color index begins to appreciably fluctuate during an eclipse of the hot component and its circumstellar envelope. About 100 days after a strong outburst of 1995, the mean UBV brightness of AS 338 declined linearly in the ensuing five years at the same rate in all bands (ΔU/Δt≈10^?3 mag/day). The brightness of the outer, uneclipsed parts of the circumstellar envelope also decreased, which is attributable to a reduction in the luminosity of the hot component against the rise in its temperature. The appearance of He II lines has not yet been recorded, though the optical brightness of AS 338 has already dropped by ～2^m after the outburst.     

Study of the weakly magnetic star HD 116656

Astronomy Letters - We studied the spectroscopic binary HD 116656 (ζ1 UMa) that has previously been suspected to be a Si-type chemically peculiar star. The magnetic field of each individual...     

Petrological constraints on the formation conditions and retrograde P–T path of the Kotsu eclogite unit, central Shikoku

A largely undocumented region of eclogite associated with a thick blueschist unit occurs in the Kotsu area of the Sanbagawa belt. The composition of coexisting garnet and omphacite suggests that the Kotsu eclogite formed at peak temperatures of around 600 °C synchronous with a penetrative deformation (D1). There are local significant differences in oxygen fugacity of the eclogite reflected in mineral chemistries. The peak pressure is constrained to lie between 14 and 25 kbar by microstructural evidence for the stability of paragonite throughout the history recorded by the eclogite, and the composition of omphacite in associated eclogite facies pelitic schist. Application of garnet‐phengite‐omphacite geobarometry gives metamorphic pressures around 20 kbar. Retrograde metamorphism associated with penetrative deformation (D2) is in the greenschist facies. The composition of syn‐D2 amphibole in hematite‐bearing basic schist and the nature of the calcium carbonate phase suggest that the retrograde P–T path was not associated with a significant increase or decrease in the ratio of P–T conditions following the peak of metamorphism. This P–T path contrasts with the open clockwise path derived from eclogite of the Besshi area. The development of distinct P–T paths in different parts of the Sanbagawa belt shows the shape of the P–T path is not primarily controlled by tectonic setting, but by internal factors such as geometry of metamorphic units and exhumation rates.     

Sources of Inaccuracy in Boron Isotope Measurement Using LA-MC-ICP-MS

Laser ablation multi-collector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) has become a valuable tool for the in situ measurement of the boron isotope composition of geological samples at high (tens to hundreds of μm) spatial resolution. That said, this application suffers from significant analytical challenges. We focus in this study on the underlying processes of two of the main causes for inaccuracies using this technique. We provide empirical evidence that not only Ca ions (Sadekov et al. 2019, Standish et al. 2019, Evans et al. 2021) but also Ar ions, that are reflected within the flight tube of the mass spectrometer, are the source for previously reported issues with spectral baselines. We also address the impact of plasma conditions on the instrumental mass fractionation as a source for matrix- and mass-load-related analytical biases. Comparing experimental data with the results of a dedicated release and diffusion model (RDM) we estimate that a close to complete (~ 97%) release of boron from the sample aerosol is needed to allow for consistently accurate LA boron isotope measurement results without the need for corrections.     

A Numerical Simulation Study of Temperature and Pressure Effects on the Breakthrough Pressure of CO2 in Unsaturated Low-permeability Rock Core

Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock, and it also plays important roles in safety and capacity of CO2 geological storage. Based on the published experimental results, we present numerical simulations on CO2 breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions (which can keep CO2 in gaseous, liquid and supercritical states) and thus, a numerical method which can be used to accurately predict CO2 breakthrough pressure on rock-core scale is proposed. The simulation results show that CO2 breakthrough pressure and breakthrough time are exponential correlated with P-T conditions. Meanwhile, pressure has stronger effects on experimental results than that of temperature. Moreover, we performed sensitivity studies on the pore distribution index λ (0.6, 0.7, 0.8, and 0.9) in van Genuchten-Muale model. Results show that with the increase of λ, CO2 breakthrough pressure and breakthrough time both show decreasing trends. In other words, the larger the value of λ is, the better the permeability of the caprock is, and the worse the CO2 sealing capacity is. The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies.     

我国陆相中高熟页岩油富集条件与分布特征

我国相继在多个盆地陆相页岩油勘探中获得突破,展示了良好的发展前景。基于现阶段勘探认识,本文认为陆相页岩油富集主要条件是：(1)稳定且有规模和适宜热成熟度的富有机质页岩是重要物质基础,以TOC含量>2%,最佳为3%～4%、母质类型Ⅰ和Ⅱ₁型为主,R_o>0.9%或更高(咸化环境0.8%);(2)有一定容积规模的微纳米孔隙且具脆性的多类储层是重要条件,页岩储层有效孔隙度宜>3%～6%;成岩阶段偏低时,纯页岩段不是中高熟页岩油富集段,致密砂岩和混积岩黏土含量宜<20%;成岩阶段高时,页岩黏土含量可高至40%左右;(3)滞留烃数量大且品质好是重要保证,以S₁>2 mg/g为门限,最佳>4～6 mg/g;气油比>80 m³/m³,最佳150～300 m³/m³;(4)顶底板具封闭性保持超压且滞留足够多轻-中组分烃类。陆相页岩油分布特征是：(1)有外物质注入的深-半深湖相是页岩油主要富集区;(2)具备“四高...