Seven years photometry of the W UMa‐type eclipsing binary V2612 Oph     

O. zdarcan  G. Ta 《Astronomische Nachrichten》2014,335(8):833-840

We present the first long‐term Johnson UBVR observations and comprehensive photometric analysis of the W UMa‐type eclipsing binary V2612 Oph. Observations in the time interval between 2003 and 2009 enabled us to reveal the seasonal and long‐term variations of the light curve. Hence, we found that the mean brightness level of the light curve shows a variation with a period of 6.7 years. Maximum and minimum brightness levels of the light curve exhibit a variation from year to year which we attribute to a solar‐like activity. The O – C variation of eclipse timings of the system shows a decreasing parabolic trend and reveals a period decrease at a rate of P = 6.27×10^‐7 day yr^‐1 with an additional low‐amplitude sinusoidal variation that has a similar period as the long‐term brightness variations. Our light curve analysis shows that the system is a W‐subtype W UMa eclipsing binary. We calculated masses and radii of the primary and secondary components as M₁ = 1.28 M_⊙, M₂ = 0.37 M_⊙ and R₁ = 1.31 R_⊙, R₂ = 0.75 R_⊙, respectively. The derived absolute photometric parameters allow us to calculate a distance of 140 pc, which confirms that the system is a foreground star in the sky field of the Galactic open cluster NGC 6633. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Applicability of colour index calibrations to T Tauri stars     

T. Schning  M. Ammler 《Astronomische Nachrichten》2008,329(1):26-38

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乌鲁木齐区域高分辨率数值预报系统V2.0 预报性能客观检验          下载免费PDF全文

琚陈相  刘建军  李曼  李火青  张海亮  马玉芬 《沙漠与绿洲气象(新疆气象)》2022,16(3):38-46

数值预报系统检验结果对预报产品的释用和系统的改进有着重要的作用。基于MET（Model Evaluation Tools）检验工具对乌鲁木齐区域高分辨率数值预报系统V2.0 (Rapid-refresh Multi-scale Analysis and Prediction System—Central Asia V2.0，简称RMAPS-CA V2.0）在2021年各季节中的预报性能进行客观检验评估，主要检验了2m温度、10m风速、高空位势高度等要素，并与RMAPS-CA V1.0同期预报性能进行对比分析。（1）2m温度预报偏差在冬季和春季整体为负偏差，在夏季和秋季整体为正偏差；各个季节的平均预报偏差均在2℃以内，预报性能秋季最优，冬季最差。各个季节10m风速预报整体为正偏差且差异不大，平均误差在0.5-1.0 m/s之间，预报性能秋季最优，春季最差。（2）高空位势高度预报偏差在冬季整体为负偏差，在其余季节整体为正偏差，预报性能冬季最优，春季最差。高空风场预报偏差在冬季和春季400hPa以下为正偏差，400hPa以上为负偏差；夏季和秋季整体为负偏差，预报性能春季最优、夏季最差。高空温度场预报偏差在冬季整体为负偏差，其余季节整体为正偏差，预报性能春季最优、夏季最差。（3）降水晴雨预报效果较好，但除夏季外以空报为主；随降水阈值增大、TS评分减小，多以漏报为主，降水评分在冬季最高、夏季最低。从降水个例检验看，24h累计降水为大量和中量的国家站点预报性能有所提升，逐6h累计降水TS评分略有提升。（4）RMAPS-CA V2.0系统各要素预报偏差的变化特征与RMAPS-CA V1.0相似，预报能力整体上要优于RMAPS-CA V1.0。  相似文献   

8410型直读光谱仪中开关电源工作原理及维修     

孙荣霞王永青  高月华孙英建赵晓博  柴宏文张天佑 《岩矿测试》2003,22(3):239-240

在维修和改造8410型电感耦合等离子体直读光谱仪过程中,经常需要对ICP高频发生器中的开关电源进行维修和调整。简述开关电源基本原理,介绍-145V开关电源稳压过程及故障维修。  相似文献   

A photometric study of V608 Cam: apparent period changes as a result of surface activity     

《New Astronomy》2022

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First photometric and orbital period investigations of the total-eclipse contact binary V0339 Com     

《New Astronomy》2022

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First photometric study of two eclipsing binary star systems: V523 And and V543 And     

《New Astronomy》2022

Detailed photometric analysis of V523 And and V543 And from the Wide Angle Search for Planets survey is presented for the first time. It was found that while V523 And is a detached binary, V543 And is a semi-detached binary star system. The adopted masses and radii for the primary and secondary components are $M_1=0.77\pm 0.08$ M${}_{\odot }$, $R_1=0.87\pm 0.08$ R${}_{\odot }$ and $M_2=0.50\pm 0.12$ M${}_{\odot }$, $R_2=0.77\pm 0.17$ R${}_{\odot }$ for V523 And; and $M_1=1.59\pm 0.16$ M${}_{\odot }$, $R_1=1.46\pm 0.09$ R${}_{\odot }$ and $M_2=0.58\pm 0.17$ M${}_{\odot }$, $R_2=1.66\pm 0.22$ R${}_{\odot }$ for V543 And. Orbital period variations of the systems were analyzed using the O-C method. The O-C change of V523 And is discussed in terms of the magnetic activity cycle of one or both components and light travel time effect (LTTE) due to a third body in the system. Among these mechanisms, LTTE seems to be the most appropriate mechanism to explain the O-C variation of the system since the quadrupole moments of the primary and secondary components ($\Delta Q$) were found to be in the order of $10^{49}$ g cm${}^2$. The O-C diagram of V543 And shows a downward parabolic trend, which suggests a secular period decrease with a rate of $0.080\pm 0.012$ s/year. The parabolic O-C variation of V543 And was interpreted in terms of the non-conservative mass transfer mechanism. According to this scenario, the range of possible values of the mass gain rate (${\dot{M}}_1$) of the primary component of V543 And as well as the mass-loss rate ($\dot{M}$) of the system were found to be $10^{-5}$–$10^{-11}$ M${}_{\odot }$/year and $10^{-6}$–$10^{-8}$ M${}_{\odot }$/year, respectively.  相似文献   

Absolute parameters of four W UMa stars with extreme low mass ratios     

《New Astronomy》2022

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Study on the variation of orbital period,quasi-periodic oscillations and negative superhumps in V729 Sgr     

《New Astronomy》2022

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First TESS light curve solution and orbital period analysis of V567 And     

《New Astronomy》2022

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