Variations of the Orbital Period of an Eclipsing Binary W Del

Astronomy Reports - We have performed an analysis of the variations of the orbital period of the eclipsing binary system W Del. It is shown that its period changes with almost equal accuracy can be...     

Variations in the Orbital Periods of Eclipsing Binaries RY Aqr,AK Vir,and AX Vul

Astronomy Reports - Variations in the orbital period of eclipsing binaries RY Aqr, AK Vir, and AX Vul are studied. It is shown these variations can be represented with equal accuracy in two ways:...     

Multiperiodicity in the Orbital Period Variations of the Eclipsing Binary System Z Per

Astronomy Reports - The variations in the orbital period of the eclipsing binary system Z Per have been analyzed. It has been shown that the variations in the period can be represented as a...     

Variations in the Orbital Period of the Eclipsing Binary System V505 Sgr

Astronomy Reports - The variations in the orbital period of the eclipsing binary system V505 Sgr, which is a part of the visual binary system CHR 90, have been analyzed. It has been shown that the...     

The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau

A detailed study of the orbital-period variations of the Algol-type eclipsing binaries with earlyspectral- type primary components U CrB and RW Tau has been performed. The period variations in both systems can be described as a superposition of secular and cyclic variations of the period. A secular period increase at a rate of 2.58^d × 10^?7/year is observed for U CrB, which can be explained if there is a uniform flow of matter from the lower-mass to the higher-mass component, with the total angular momentum conserved. RW Tau features a secular period decrease at a rate of ?8.6^d × 10^?7/year; this could be due to a loss of angular momentum by the binary due to magnetic braking. The cyclic orbital-period variations of U CrB and RWTau can be explained by the motion of the eclipsing binary systems along their long-period orbits. In U CrB, this implies that the eclipsing binary moves with a period of 91.3 years around a third body with mass M₃ > 1.13M_⊙; in RW Tau, the period of the motion around the third body is 66.6 years, and the mass of the third body is M₃ > 1.24M_⊙. It also cannot be ruled out that the variations are due to the magnetic cycles of the late-type secondaries. The residual period variations could be a superposition of variations due to non-stationary ejection of matter and effects due to magnetic cycles.     

Orbital-Period Variations of the Eclipsing Binaries RY Aur,GG Cas,RS Lep,and RV Tri

Variations of the orbital periods of the eclipsing binaries RY Aur, GG Cas, RS Lep, and RV Tri are analyzed. The period variations in all of these systems can be represented as a superposition of a secular period decrease and cyclic variations that can be explained with the light-time effect due to the presence of a third body in the system. The secular period decrease could be due to magnetic braking.

     

Eclipsing Binary Systems XZ Per and BO Vul with Complex Variations in Orbital Periods

Astronomy Reports - The variations in the orbital periods of the eclipsing binary systems XZ Per and BO Vul have been studied. It has been shown that the variations in the orbital period of the...     

Cyclic Orbital-period Variations in Eclipsing Binary Systems with Rapid Period Decreases: TU Her,TY Peg,and Y Psc

Cyclic variations of the orbital period superposed on a secular period decrease have been found for the Algol-type eclipsing binaries TU Her, TY Peg, and Y Psc. A superposition of two kinds of cyclic variations is observed for TU Her and Y Psc: with periods of 69.4 years and 30.0 years for TU Her, and 34.4 and 23.2 years for Y Psc. One type of oscillation, with a period of 74.3 years, was detected for TY Peg. The cyclic orbital-period variations of TY Peg and Y Psc can be successfully fitted using the light-time effect, and also with magnetic oscillations. In the case of TU Her, the light-time effect is able to explain only one of the cyclic variations, the one with the shorter period.     

A Double Wave in the Orbital-period Variations of the Eclipsing Binary RT Per

Orbital-period variations of the low-mass, semi-detached eclipsing binary RT Per are analyzed. In addition to the secular variation of the orbital period determined by the mass transfer between the components, cyclic variations are also present. Both the light-time effect and magnetic oscillations can describe the cyclic orbital-period variations of RT Per. The secular period increase can be explained by a uniform flow of matter from the lower-mass to the higher-mass component at a rate of 0.60 × 10⁻⁸M-/year, with the total angular momentum being conserved. The period variations can be represented equally accurately by either a superposition of two cyclic variations or a superposition of a secular period increase and two cyclic variations. Approximately the same parameters are derived for the lower-period (36.8 year) variations when the times of minima are fitted with a linear or a quadratic formula. For the longer-period variation, a period of 275 years and amplitude of 0.104 days are found using the linear formula, or 89 years and 0.045 days using the quadratic formula.

     

Photometric activity of UX Ori stars and related objects in the near infrared and visual. BF Ori, CQ Tau, WW Vul, and SV Cep

We have analyzed the activity of four UX Ori stars in the near-IR (JHKL) and visual (V) using the results of long-term photometric observations. For comparison, we also obtained IR (JHKLM) photometric observations of two visually quiet young stars of close spectral types (AB Aur and HD 190073). For the photometrically most active UX Ori stars BF Ori, CQ Tau, and WW Vul, the Algol-like declines of brightness in the visual, which are due to sporadic enhancements of the circumstellar extinction, are also observed (with decreasing amplitude) in the IR bands. A strict correlation between the V and J brightness variations is observed for all the stars except for SV Cep. For some of the UX Ori stars, a strong correlation between the visual and IR activity is observed up to L, where the main contribution to the emission is made by circumstellar dust. In the case of SV Cep, the visual variability is not correlated with the variability of the IR fluxes. On one occasion, a clear anti-correlation was even observed: a shallow, but prolonged decrease of the visual brightness was accompanied by an increase in the IR fluxes. This indicates that circumstellar clouds themselves can become powerful sources of IR emission. Our results provide evidence that the photometric activity of UX Ori stars is a consequence of instability of the deepest layers of their gas-dust accretion disks. In some cases (SV Cep), fluctuations of the density in this region are global, in the sense that they occur along a significant part of the circle marking the inner boundary of the dust disk. It is interesting that AB Aur, which is the quietest in the visual, appeared to be the most active in the IR. In contrast to UX Ori stars, the amplitude of its brightness variations increases from the J to the M band. It follows from analysis of the IR colors of this star that their variability cannot be described by models in which the variable IR emission has a temperature close to the sublimation temperature of silicate grains (about 1500 K). This means that the photometric activity of AB Aur must be due to both the dust and gas components of the circumstellar disk.     

丰水期红枫湖流域氮污染特征的变化规律研究

丰水期对汇入红枫湖的后六河、麻线河、羊昌河和桃花园河等河水中氮素的形态和含量进行测定,结果表明NO3--N是氮素的主要形态,约占TN的25%~65%;三态氮在空间分布上,从上游至下游,四条河流表现出不同的变化规律,后六河NH4+-N、NO2--N与NO3--N的变化规律基本上一致外,含量总体上逐渐增加;其它三条河流中,NH4+-N与NO3--N的含量呈现相反的变化趋势,NO2--N的变化规律则不明显。该流域整体上表现为非点源污染的特征。后六河和麻线河地下水中NO3--N的含量明显高于相应河水中的含量。该研究对亚热带小流域河水中氮磷含量及形态变化研究具有借鉴意义,对该流域的环境规划、环境管理和环境污染治理具有指导意义。     

BVI c Observations and Search for Evolutionary Variations in the Cepheid V811 Oph Period

For the first time, BVIc observations of the Cepheid V811 Oph were obtained by using a new 60‑cm telescope at the Caucasus Mountain Observatory, Sternberg Astronomical Institute, Moscow State University (SAI MSU). An $$O{-}C$$ diagram covering a time span of 124 years was plotted using photometry from old photographic and modern sky surveys. The diagram has a parabola shape, which made it possible to determine for the first time the quadratic elements of the brightness variations. Furthermore, it made it possible to calculate the rate of an evolutionary decrease in the period of V811 Oph $$dP{\text{/}}dt = - 0.00375( \pm 0.00177)$$ s/year, which is consistent with the theoretical calculation results for the second intersection of the instability strip if this Cepheid is a classical one. The pulsation stability test proposed by Lombard and Koen confirmed the actual decrease in the period.     

Hydrogeochemistry and cation-exchange processes in the coastal aquifer of Mar Del Plata,Argentina

The aquifer of Mar del Plata is unconfined and composed of silt and fine sand. The sand fraction is mainly quartz, potassium feldspars, chalcedony, and gypsum. Volcanic-glass shards (40–60%) dominate the silt fraction, and the clays are of the smectite and illite groups. Calcium carbonate, in caliche form, constitutes about 10–20% of the sediment. Groundwater flow is from west to east, and discharge is in the Atlantic Ocean. Because of overexploitation, the flow direction was reversed in a coastal belt about 3.5 km wide, and this has resulted in seawater intrusion. The groundwater is the CaHCO₃ type in the recharge zone, and becomes NaHCO₃ type towards the discharge area. Salinization by marine intrusion and seawater/fresh-water mixing produces an increase in the major-ion concentrations of the groundwater. The calcium content of the groundwater is higher and the sodium content is lower than those that would be expected if the mixing is considered as just the addition of seawater and fresh water in determined proportions without reactive processes taking place. Hydrogeochemical modeling was applied to the study of hydrogeochemical processes, mainly cation exchange, using the codes NETPATH and PHREEQM. Calcite and gypsum equilibrium, together with cation exchange, are the main hydrogeochemical processes. Cation-exchange capacity of the solid phase was determined by empirical calculations and experimental methods. The affinity order for the groundwater in contact with the aquifer matrix is Ca>Mg>Na in the regional-flow system, but the order is reversed in the salinization process. Reactive transport modeling using the code PHREEQM is useful for analyzing cation exchange in a marine-intrusion process. Electronic Publication     

Variations in Sediment Yield from the Upper Doubs River Carbonate Watershed (Jura, France) since the Late-Glacial Period

The Upper Doubs River Valley is a 910-km²watershed feeding into Lake Chaillexon. The lake was formed by a natural rockfall at the end of the Bølling Chronozone (around 14,250 cal yr B.P.) and since then has trapped material eroded from the watershed. The filling process and variations in sediment yield have been investigated by mechanical coring, seismic surveys, and electric soundings. The detrital sediment yield of the upstream watershed can be calculated by quantifying the sedimentary stocks for each climatic stage of the Late-Glacial period and Holocene Epoch and estimating the lake's entrapment capacity. This enables us to determine the intensity of the erosion processes in relation to climate and environmental factors. The Bølling–Allerød Interstade produced the greatest yields with mean values of 19,500 metric tons per calendar year (t/yr). The Younger Dryas Chronozone saw a sharp fall (8900 t/yr) that continued into the Preboreal (2100 t/yr). Clastic supply increased during the Boreal (4500 t/yr) before declining again in the Early Atlantic (2400 t/yr). Since then, yields have risen from 4500 t/yr in the Late Atlantic to 6800 t/yr in the Subboreal and 11,100 t/yr in the Subatlantic. Comparison of quantitative data with the qualitative analysis of the deposits and with the paleohydrologic curve of the watershed based on level fluctuations in lakes around Chaillexon shows that climate was the controlling factor of sediment yield until the Late Atlantic. From the Late Atlantic–Subboreal around 5400 cal yr B.P. (4700¹⁴C yr B.P.) and especially from the end of the Subboreal Chronozone and during the Subatlantic Chronozone (2770 cal yr B.P./2700¹⁴C yr B.P.–present) climatic constraints have been compounded by human activity related to forest clearing and land use.     

2007-2011年西藏纳木错流域积雪时空变化及其影响因素分析

通过2007-2011年纳木错站人工积雪观测资料,对西藏纳木错流域MODIS两种积雪产品(MOD10A1和MOD10A2)进行了精度验证,分析了纳木错流域积雪累积和消融的空间差异,以及流域积雪覆盖率的时空变化;利用纳木错站人工积雪观测资料及自动气象站资料,分析了纳木错流域积雪要素(积雪深度、雪水当量、积雪密度)的时间变化及其与气候参数(气温、降水量、风速等)的关系.结果表明：纳木错流域MOD10A2数据的积雪识别精度(67.1%)高于MOD10A1(42.2%),总识别精度(73.0%)略低于MOD10A1数据(78.4%).纳木错流域积雪累积和消融存在空间差异,积雪在流域南部的念青唐古拉山脉最先累积,之后为流域东部,最后为流域西部;积雪消融的空间变化则相反.由此导致流域积雪日数南部最大、东部次之、西部及西北部最小.纳木错流域各积雪要素的年内变化存在双峰值特征,峰值分别出现在10-11月和1月,积雪在10-11月受降水和气温共同作用,12月至次年3月主要受气温影响.纳木错流域的平均积雪覆盖率为21.9%,受湖泊效应影响区域(主要为东部地区)达到50.6%,而其他区域仅为18.3%.同时,受湖泊效应影响,纳木错平均积雪深度、积雪水当量均显著大于周边地区.     

Orbital period variations of the eclipsing binaries TU Cnc,VZ Leo,and OS Ori

Variations of the orbital periods of the eclipsing binaries TU Cnc, VZ Leo, and OS Ori are analyzed. Secular period decreases were earlier believed to occur in these systems. It is demonstrated that the period variations of TU Cnc can be represented using the light-time effect corresponding to the orbital motion of the eclipsing binary with a period of 78.6 years around the center ofmass of the triple system, with the mass of the third body being M ₃ > 0.82M _⊙. With the same accuracy, the period variations of VZ Leo and OS Ori can be represented either solely using the light-time effect, or a superposition of a secular period decrease and the light-time effect. For VZ Leo, the period of the long-term orbit is 63.8 years in the former case and 67.9 years in the latter case. Similar masses for the third body are indicated in both cases: M ₃ > 0.55M _⊙ and M ₃ > 0.61M _⊙. For OS Ori, the period of the long-term orbit is 46 years and M ₃ > 0.5M _⊙ in the former case, and the period is 36 years and M ₃ > 0.6M _⊙ in the latter case.     

山东临朐一带古近——新近纪地层的划分

根据昌乐、临朐一带古近-新近纪地层重点勘查成果及发现的孢粉、微体及腹足类化石等资料,认为昌乐五图组中的煤及油页岩地层年代为古近纪中始新世;临朐牛山七贤店山沟中出露的一套粘土岩、泥岩夹含油泥岩,可与五图组上煤段对比,其地层年代为中始新世晚期;临朐山旺村山沟中出露的一套粘土岩夹硅藻岩等,前人认为地层年代为中新世山旺组．本次勘查获得的孢粉谱对其提供了佐证;柳山坪南头村山顶上出露一套厚层花岗质含砾粗砂岩（底部夹泥煤一层）,平覆在花岗片麻岩山顶,依孢粉谱与山旺组对比,其地层年代要晚于山旺组,可与尧山花岗片麻岩山顶的尧山组相比。地层年代属于上新世尧山组。     

Variations of the 238U/235U Isotope Ratio in Metasedimentary Rocks and Evidence of Changes in Sedimentation Conditions during the Ediacarian Period of the Neoproterozoic

Doklady Earth Sciences - The isotopic composition of uranium is a new geochemical indicator that facilitates reconstruction of the redox conditions of geological processes. In this paper the...     

Determination of Zn partition coefficient and simulation of reactive transport from landfills in Mar Del Plata, Argentina

The distribution coefficient (Kd) expresses the relationship between the concentration of an element, which is adsorbed in the solid surface and its remaining concentration in the solution. The Kd is a very important factor in reactive transport, representing the source/sink term, and explaining the difference between the velocity of transport of non-conservative elements (Kd>0) and water flow velocity. In this paper, the Kd value for Zn element in loess like sediments forming the Pampeano aquifer is determined and this value is used in the modeling of reactive transport from the landfill of the city of Mar del Plata (Argentina). The determination of Kd value was done by means of batch experiments. The results obtained showed good agreement with Freundlich isotherm, with a value of K_F=300.95 ml g⁻¹ and a super index value b of 0.3961. These values were applied to reactive transport modeling using Visual Modflow code. The Zn plume obtained showed the low mobility of the element in the oxidizing conditions of the environment.