共查询到20条相似文献，搜索用时 140 毫秒
1.
The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar Observatory.However,the liquid crystals based Stokes polarimeter in space is not a mature technology.Therefore,it is of great scientific significance to study the control method and characteristics of the device.The retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field measurement.In order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in space.In order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed theoretically.By analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating films.The experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or vacuum.The temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarimeter. 相似文献
2.
At present, optical autonomous navigation has become a key technologyin deep space exploration programs. Recent studies focus on the problem of orbit de-termination using autonomous navigation, and the choice of filter is one of the mainissues. To prepare for a possible exploration mission to Mars, the primary emphasisof this paper is to evaluate the capability of three filters, the extended Kalman filter（EKF）, unscented Kalman filter （UKF） and weighted least-squares （WLS） algorithm,which have different initial states during the cruise phase. One initial state is assumedto have high accuracy with the support of ground tracking when autonomous navi-gation is operating; for the other state, errors are set to be large without this support.In addition, the method of selecting asteroids that can be used for navigation fromknown lists of asteroids to form a sequence is also presented in this study. The simula-tion results show that WLS and UKF should be the first choice for optical autonomousnavigation during the cruise phase to Mars. 相似文献
3.
4.
5.
空间望远镜的研制一直要求系统的轻量化,美国宇航局(NASA)最近研制的韦伯太空望远镜,其主镜系统面密度相对于哈勃空间望远镜已大幅减轻.在韦伯望远镜主镜系统的研制过程中,NASA开展了一系列关于超轻量镜面系统的验证计划,多家机构拿出多个方案参与竞标.本文选取几个比较典型的方案,介绍这些镜面系统的设计思想、结构、材料、加工以及相关测试结果,期望能对国内相关方面的工作提供参考. 相似文献
6.
黑洞也可以蒸发天文学的发展遵循着一条规律:观测、理论、再观测、再理论……这大概也是任何一门自然科学的发展规律,只不过天文学表现得更为突出,而在漫长的发展过程中,观测又始终是天文科学的真谛。因此,天文学又被称为是一门观测的科学。黑洞的观测证据越来越丰富,黑洞对宇宙的威胁也越来越严重。理论天文学家必须出来释疑,让黑洞不仅能吃进去,还要吐出来。吐出来的困难在于黑洞的引力太强,在黑洞的视 相似文献
7.
张衡字平子,河南省南阳县人,生于公元78年,逝世于139年;今年是他诞生的1880周年。公元第一世纪末和第二世纪初,是东汉王朝的繁荣时期,那时它是世界上的四大强国之一(另外三个是匈奴、大月氏和罗马帝国),国内在经济上、文化上和交通上都有相当的发展。这样的和平环境提供了良好的条件, 相似文献
8.
来参观过 starry 和 yvonne 的天文小屋的朋友,对我们卧室的满天星效果赞不绝口。开关一开,就看到完全根据《全天星图2000》临摹的夏夜星空,满天繁星一闪一闪的,还可以变化颜色。躺在床上数星星,不可不谓一种浪漫、惬意的享受啊。天文同好们应该都有自己家里看到星空的想法吧?最开始我是买了 HOMESTAR PRO,平心而论,这种家庭天象仪的效果已经很 相似文献
9.
根据13C辐射燃烧的低质量AGB(Asymptotic Giant Branch)星s-过程核合成模型,考察了氦壳层核合成区域中子辐照量分布(以下简称DNE)的特点.结果表明,该模型的DNE同以前的对流核合成模型一样仍然非常接近指数分布,但是每个脉冲的中子辐照量△r和平均中子辐照量To之间的关系却不再是To=-△T/lnr,而近似为To=-△r/ln{q[1.0020 0.6602(r-q) 4.6125(r-q)2-10.8962(r-q)3 13.9138(r-q)4]}(r为重叠因子, q为13C壳层占氦壳层的质量比例).该式从DNE角度将辐射s-过程恒星模型和经典模型统一起来. 相似文献
10.
用CHAMP加速仪数据校验太阳活动峰年的大气模型精度 总被引：6，自引：0，他引：6
介绍CHAMP星载加速仪数据的处理方法.通过对实测数据的分析证实仪器的x轴存在故障.为了研究太阳活动峰年大气模型的精度,处理了2001至2002年的加速仪数据,利用切向非引力加速度反算大气密度.然后从统计的角度分析DTM94和MSIS90大气模型的误差,得到一些定量的结论,太阳活动峰年DTM94的误差为30%-35%,MSIS90的误差为25%-30%,MSIS90比DTM94误差小,模型间最大差异约10%. 相似文献
11.
Slavek M. Rucinski Wenxian Lu 《Monthly notices of the Royal Astronomical Society》2000,315(3):587-594
Radial velocity data for both components of W Crv are presented. In spite of providing full radial-velocity information, the new data are not sufficient to establish the configuration of this important system because of large seasonal light curve perturbations, which prevent a combined light curve/radial-velocity solution. It is noted that the primary minimum is free of photometric perturbations, and this property may help to explain the elusive source of these perturbations. Photometrically, the system appears to be a contact binary with poor or absent energy exchange, but such an explanation – in view of the presence of light curve perturbations – is no more plausible than any one of the semi-detached configurations, with either the more-massive or less-massive components filling the associated Roche lobes. Lengthening of the orbital period and the size of the less-massive component above its main-sequence value, both suggest that the system is the shortest-period (0.388 d) known Algol with non-degenerate components. 相似文献
12.
Some properties of mass transfer within a semi-detached binary system are discussed based on an example of VV Vir.The observations and analysis of VV Vir show that it is a semi-detached binary system with the less massive cooler component filling its Roche lobe,which is also called an Algol-type binary system.Based on the parameters of this semi-detached binary,a theoretical study on the mass flow is carried out,including the trajectory of the mass flow,the position,radius and temperature of the impact spot caused by the mass flow,the inconsistent form of the mass flow and the possibly huge rate of energy transfer carried by the mass flow.Humps and distortions in light curves of VV Vir are deemed to be weak evidence for the theoretical results. 相似文献
13.
Qian Shengbang 《Astrophysics and Space Science》2000,274(4):711-718
The photoelectric observations of the neglected binary AV Hya published by Srivastava and Kandpal (1980) have been re-analyzed using Wilson-Devinney's synthetic light-curve program. The binary turns out to be a near-contact semi-detached system. The primary, more massive, more luminous and greater component, eclipsed at primary minimum, is detached from its Roche lobe (85%). The secondary fills its Roche lobe and has a temperature difference of T=,-3414 K. As with other semi-detached binaries, the secondary is more evolved than that of the primary. Thetimes of light minima of the eclipsing have been analyzed,showing that the orbital period of AV Hya undergoes acontinuous decrease with a rate of dP/dE=-8.26×10-8 day/year. The mass transfer between the twocomponents can not explain the present orbital period variationsince the secondary component is filling the Roche lobe. Theorbital period change demonstrates that the system may undergoa secular mass and angular momentum loss and the system mayevolve from the present short-period near-contact system intoan A-type contact binary. 相似文献
14.
The UBV photometric observations of RT Per, from Sanwal and Chaubey (1981), were analyzed by the Wilson and Devinney code (1971). The light curves include reflection effects that for the first time has been suggested by Dugan (1911). RT Per has a semi-detached configuration where the lower-mass component is in contact with its respective Roche surface. The higher-mass component very nearly fills its Roche lobe. It has the characteristic of an Algol type system. The absolute dimensions for the primary and secondary of this system were calculated from its spectral types and by combining the photometric solution with inferred component radial velocities (Lu, 1990). 相似文献
15.
In this study we present the new R and I light curve solutions for the eclipsing binary systems RW CrB and VZ Leo, which for
VZ Leo is the first one in the literature. Our new observations have been analyzed using the Wilson-Devinney code from which
new geometric and photometric elements are derived. The geometry of both stars is that of a semi-detached binary system where
the secondary component fills its Roche lobe while the primary component is well inside. In the case of RW CrB, asymmetry
in the light curve was explained by a spot model. The orbital period changes of both systems were studied and the results
indicated a period decrease which can be explained by angular momentum loss. We also investigated the possibility of pulsations
of the primary components since these systems are mentioned as candidates of δ Sct type pulsation. However, a time-series analysis of the residual curves in the filter I does not indicate any evidence
of periodic light variation for both systems. Finally, we compared the results obtained for both binary stars to those of
similar systems. 相似文献
16.
《New Astronomy》2019
SuperWASPJ222302.02+195031.8 is an eclipsing binary with an orbital period about 0.22517657 days that is close to the short-period limit of contact binaries. Multi-color photometric light curves of the short-period binary in B, V, Rc and Ic bands are presented and analyzed by using the Wilson–Devinney (W–D) method. It is discovered that the system is a semi-detached binary where the secondary component is already filling the critical Roche lobe, while the primary is filling just 77.1% of its Roche lobe. The temperature of the primary is about 4300 K, and the temperature difference between the two components is about 500 K. The asymmetries in the light curves are explained by the coverage of stellar dark spots on the less massive component via magnetic activity. An analysis of all available eclipse times suggests that there are no any changes in the O-C diagram. This may indicate that there are no mass transfers between the two components. The semi-detached configuration with the dark spot on the surface of the lobe-filling secondary and no variations in the orbital period make the binary an interesting target for further investigations. 相似文献
17.
K. Li S.-M. Hu D.-F. Guo Y.-G. Jiang D.-Y. Gao X. Chen 《Journal of Astrophysics and Astronomy》2016,37(3):16
Four color light curves of the EW type eclipsing binary V441 Lac were presented and analyzed by the W–D code. It is found that V441 Lac is an extremely low mass ratio (q = 0.093±0.001) semi-detached binary with the less massive secondary component filling the inner Roche lobe. Two dark spots on the primary component were introduced to explain the asymmetric light curves. By analyzing all times of light minimum, we determined that the orbital period of V441 Lac is continuously increasing at a rate of dP/dt = 5.874(±0.007) × 10?7 d yr?1. The semi-detached Algol type configuration of V441 Lac is possibly formed by a contact configuration destroyed shallow contact binary due to mass transfer from the less massive component to the more massive one predicted by the thermal relaxation oscillation theory. 相似文献
18.
Ö. L. Deĝirmenci Ö. Gülmen C. Sezer N. Güdür A. Erdem 《Astrophysics and Space Science》1996,241(2):327-332
Photoelectric B and V light curves of the eclipsing binary V1425 Cygni were analyzed by the method of Wilson-Devinney. The system was found to be a semi-detached binary where the secondary component (less massive and cooler) fills its Roche lobe. 相似文献
19.
Two eclipsing binary systems,UZ Lyr and BR Cyg,are semi-detached types whose secondary component fills its Roche lobe.Although radial velocity and light curves ... 相似文献
20.
Vassilios N. Manimanis Chloe Vamvatira-Nakou Panagiotis G. Niarchos 《Astrophysics and Space Science》2009,323(2):115-121
A photometric analysis of the short-period Algol eclipsing binary system BF Velorum based for the first time on complete BVRI
CCD light curves is presented. The new photometric solution obtained with the Wilson-Devinney program reveals that BF Vel
is a near-contact semi-detached system with its secondary component filling its Roche lobe. Moreover, we discovered pulsations
of one member of the binary system, the analysis of which shows main frequencies of 44.9386 and 33.6731 cycles/day. Absolute
elements of the system were calculated, and the evolutionary status of its members was estimated.
相似文献