抚仙湖及其附近地震地质构造和地震活动特征的初步探讨

位处小江断裂带西支的抚仙湖周边地区是云南省潜在的强震危险区之一.该地区不仅历史上发生过5级(Ⅵ度)以上破坏性地震,而且曾多次受到相邻地区≥6级地震的波及.从地震地质构造分析和近年地震活动特征来看,抚仙湖及周边地区仍是未来7～7.5级地震的潜在震源区.因此,按照<防震减灾法>、<云南省防震减灾条例>和<玉溪市防震减灾实施办法>有关规定,建议中国科学院云南天文台对在该区域老鹰地一带筹建的抚仙湖太阳观测基地和天文观测设施所在地,按照国家<工程场地地震安全性评价技术规范>技术标准进行了地震安全性评价.     

白日视宁度监测仪和在抚仙湖的初步观测结果

报导了用南方基地云南天文台太阳差分像运动视宁度监测仪和美国国立太阳天文台的太阳闪烁仪,在云南省澄江县抚仙湖老鹰地红外太阳塔选址点进行的对比观测,简要地介绍了这两种视宁度测量方法的原理,对观测的初步结果进行了分析。     

白日视宁度监测仪和在抚仙湖的初步观测结果

报导了用南方基地云南天文台太阳差分像运动视宁度监测仪和美国国立太阳天文台的太阳闪烁仪 ,在云南省澄江县抚仙湖老鹰地红外太阳塔选址点进行的对比观测 ,简要地介绍了这两种视宁度测量方法的原理 ,对观测的初步结果进行了分析。     

国内首架日冕仪落户云南丽江

日冕仪的重要功能是通过人造日食的巧妙方式来直接观测太阳最外层大气——日冕层。借助日冕仪,人们在常规太阳观测条件下就可以欣赏美丽的日冕以及壮丽的日冕爆发过程。我们的前辈自上世纪50年代末就开始了针对日冕观测址点的不断考察,但遗憾的是一直未能寻找到理想的候选点。随着近几年我国西部太阳选址工作的不断深入,我们选址科考队得到了一批颇有价值的潜在理想址点,大香格里拉地区便是其中得到证认的区域之一。滇西北的丽江高美古天文基地就位于大香格里拉地区南部,海拔较高,空气十分洁净,每年旱季日照充沛。高美古目前拥有东亚最大的地面天文望远镜集群,为我们日冕仪观测站的建立提供了极其便利的基本条件。     

遮挡效应的太阳射电观测和仿真

遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。明安图台站太阳射电望远镜(Mingantu Solar Radio Telescope, MST)在2017～2020年S, C和X频段的观测数据显示了以20 m天线和远方丘陵为障碍物的遮挡效应,并可以分为天线、大气和丘陵3个不同特性区域。基于ITU-R P.526-15建议书单刃峰绕射损耗预测方法,进行20 m天线反射面仿真建模和近似计算。观测和仿真结果显示,绕射损耗随频率变化趋势基本一致,遮挡效应与波长、障碍物特性及其相对源和接收天线的距离和角度、接收设备的天线波束和动态范围等有关。     

川西无名山天文址点GIS分析研究

随着西部天文选址工作在川西无名山地区的逐步深入,利用地理信息科学(Geographic Information System,GIS)手段收集了大量长期数据,对无名山及周边地区的地理、地质、气候、气象、社会与人口发展趋势等方面开展了详细的调查研究.资料分析结果显示:无名山地处青藏高原向东延伸的褶皱地带—典型的横断山脉地区,形成地势整体落差大、山脊走势平缓、地质结构稳定的特色.无名山区域最高点海拔高度超过5000 m,但附近存在海拔仅2000–3000 m的人口定居点多处,可实现低成本后勤保障;鲜有地震泥石流等不良地质灾害记录;大气干燥、植被稀少、地表半干旱状态;常年盛行西南风,冬季气候寒冷、降雨量稀少,夏季受南部印度洋暖湿气流影响存在明显的雨季;属大香格里拉核心地带,大气洁净度高,无沙尘暴等恶劣天气记录;年均云量少于5成,风向稳定、风速小,可利用晴日/夜数多;人口稀少、经济发展缓慢、社会和谐稳定、远离川滇藏经济相对发达地区;近年来随着本地区旅游资源开发,交通条件得到明显改善,具备高质量公路维护与日常航空运输能力,鲜有其他高原地区常见的大雪封山、航空停运等运输不畅情形发生.因此,GIS综合分析结果表明:无名山地区满足建设高海拔天文观测站的一系列基本保障条件,是我国西部难得的光学/红外天文址点资源.     

Acceleration of Numerical Integration of the Equations of Motion of Asteroids

Solar System Research - Finding and studying possible collisions of asteroids approaching the Earth requires a significant amount of computation. This paper describes the R0 program created to...     

A survey of orbits of co-orbitals of Mars

Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF₃₁, were discovered, librating about the L₅ Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ₇, to be a Trojan, associated with the L₄ Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND₄₃) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW₁₅ and 2000 TG₂, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.     

Observations of the intensity of the penumbra of sunspots

Observations of the penumbral intensity of sunspots in 13 wavelength regions are presented. In 4 wavelength regions 54 sunspots are measured. In the other wavelength regions the number of sunspots considered ranges from 3–19.The penumbral intensity alters with position within the spot. This intensity variation is found to be comparable with the change in intensity from one spot to another. The penumbral intensity is found to be independent of spot size in the sample considered.The penumbra model of Kjeldseth Moe and Maltby (1969) with = 0.055 is supported by the measurements.     

Equation of state and anisotropy of pressure of magnetars

Magnetars are the neutron stars with the highest magnetic fields up to 10¹⁵–10¹⁶ G. It has been proposed that they are also responsible for a variety of extra-galactic phenomena, ranging from giant flares in nearby galaxies to fast radio bursts. Utilizing a relativistic mean field model and a variable magnetic field configuration, we investigate the effects of strong magnetic fields on the equation of state and anisotropy of pressure of magnetars. It is found that the mass and radius of low-mass magnetars are weakly enhanced under the action of the strong magnetic field, and the anisotropy of pressure can be ignored. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars.     

Graphical representation of periodic motion of the line of nodes of the Moon

In the text-books of astronomy, sections generally related to the Moon deal with the orbital elements of the Earth-Moon system such asa, e, i, , and the time of perigee passage. While the MEAN of the first of the three elements do not vary, mean longitude of the ascending node-mean longitude of the lunar perigee and the time of perigee passage undergoes secular as well as periodic changes due predominantly to the action of the Sun's gravitational attraction. While to a certain degree, explanations related to the calculation of the lunar orbit parameters are given, not a single graphical representation of these short- or long-periodic changes are presented. We allow the number of data related to these periodic changes must cover a large span of time; and if regression of the line of nodes or advances of the line of apses are to be graphically seen, data covering 18.61 and 8.85 yr, respectively, are needed. In this work we particularly aim at the graphical representation of the periodic changes of the line of nodes.