共查询到20条相似文献，搜索用时 46 毫秒
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统计分析了太阳活动周下降段(2003～2005年)发生的76个共生CME的射电爆发事件.射电爆发资料来自国家天文台和Culgoora的微波和米波频谱仪.在76个事件中有50个快速CME和26个慢速CME.从中发现,快速CME和慢速CME的产率分别随着太阳活动周的降低而下降和上升,这可能说明CME的产率与太阳活动周中日冕磁结构的位形和位置变化有关.同时也发现,射电爆发的类型和寿命有一个变化规律,即随着频率的降低射电爆发的寿命变长,此特征支持了伴生CME的Ⅱ型爆发统一模型的思想.另外还发现在厘米一分米波范围,CME开始前后,容易发生射电Ⅲ型爆发或快速精细结构.这说明射电辐射的精细结构可能是CME的前兆现象或CME早期发展阶段由于磁重联引发的低日冕小尺度磁扰动的结果. 相似文献
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日冕物质抛射与共生射电爆发的地面和空间联测研究 总被引：1，自引：0，他引：1
引述了近年来太阳和空间物理的一大研究成果；产生日地空间射电爆发和地球物理响应的主因不是太阳耀斑，而是日冕物质抛射（CME），论述了射电爆发在研究CME中的作用；分析了1991-06-15CME事件中射电爆发和质子事件产生的物理过程；介绍了地面/空间对CME和共生射电爆发联测研究的新进展；提出了我国今后开展地面/空间联测研究的设想和建议。 相似文献
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利用国家天文台(北京和昆明)的射电频谱仪(频段为0.65~7.6 GHz)和相关的NoRH/17GHz射电以及TRACE/171 EUV和Yohkoh/SXT的观测资料,分析了2001/04/10和10/19的2个共生精细时间结构的稀有事件,这2个事件的射电爆发时间轮廓和观测特征相似,通过这2个事件的微波(17GHz)偏振观测资料的比较,发现这2个射电爆发均由包含多重(4极)磁结构的复杂活动区引起,特别指出这2个耀斑最后都导致了耀斑后相的分米波射电爆发(第二次触发耀斑),这可能是后环引起的射电爆发。它们都分别对应于双极磁位形,表明这两次触发耀斑是由相似的耀斑模型产生。2个分米波爆发可能是相似(homologous)耀斑的射电表现,可以推测这两次耀斑的驱动器可能皆是磁流浮现或对消(因为源区有新的单或双极出现或消失),而它们的触发器皆是由双极反向Y型位形(具有一个双极拱的单磁流系统)的磁重联,耀斑后环的演化是导致耀斑后相分米波射电爆发的必要条件。我们认为,这双带耀斑对应的宽带射电爆发辐射机制是回旋同步加速辐射过程,而耀斑后相的窄带分米波爆发的辐射机制是等离子体辐射过程。 相似文献
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基于我国的太阳射电宽带频谱仪(0．625～7．600GHz)在2003年10月22日～11月3日观测到8个伴生日冕物质抛射(CME)的太阳射电爆发,结合Nobeyama Radio Polarimeter(NORP)的单频观测、Nobeyama Radioheliograph (NORH)、Siberian Solar Radio Telescope(SSRT)的成像观测以及Culgoora和WAVE／WIND的低频射电频谱观测,对8个射电爆发的射电辐射特征进行了初步分析．试图从中寻找与CME伴生的射电爆发的特征。 相似文献
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从射电运动Ⅳ型爆发的特征和多频射电爆发开始时序的分析可以看出这个伴生的白光耀斑和射电爆发同是由低日冕的加速电子激活,可能通过非热电子沉降能量于色球层,产生了色球层压缩波,又经二步能量传输过程过程中在上光球导致ＷＬＦ。通过对共生事件的分析,并与已知的二类ＷＬＦ的观测特征作了比较,提出该ＷＬＦ可能属于二类的混合型,并提出了ＷＬＦ可能存在射电辐射的必要条件。 相似文献
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一个多次产生CME的活动区特征分析 总被引：1，自引：1，他引：0
1998年4月－5月8210活动区在日面上接连出现6次大的爆发活动，搜集了这个活动区在整个日面上软X射线曲线，射电Ⅱ、Ⅳ型爆发，射电日像仪和远紫外观测等资料，它的能量积累过程快，3次软X射线爆发曲线的时间轮廓有一定的相似性。发生日冕物质抛射（CME）时，它的磁环只是局部开放，很快又收拢成一个闭合磁环，在一些非热电子的轰击下，再度被加热，又产生了强列的X射线爆发和射电Ⅱ、Ⅳ型爆发，磁环的薄弱处犹如一个活火山口，CME容易从此处再次喷发，找到非热过程与热过程衔接的拐点，在SXR时间轮廓曲线上它表现为斜率突变点，往往有Ⅲ型爆发作为对应的标志，日冕不同层次上先后出现的Ⅱ型爆发可作为CME出现的有力证据，并可作为判断CME运动速度的依据。 相似文献
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从射电运动Ⅳ型爆发的特征和多频射电爆发开始时序的分析可以看出这个伴生的白光耀斑（ Ｗ Ｌ Ｆ） 和射电爆发同是由低日冕的加速电子激活,可能通过非热电子沉降能量于色球层, 产生了色球层压缩波, 又经二步能量传输过程在上光球层导致 Ｗ Ｌ Ｆ。通过对共生事件的分析, 并与已知的二类 Ｗ Ｌ Ｆ的观测特征作了比较, 提出该 Ｗ Ｌ Ｆ 可能属于二类的混合型, 并提出 Ｗ Ｌ Ｆ 可能存在射电辐射的必要条件 相似文献
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介绍云南和北京天文台射电频谱仪观测到的3个对偶的米波－－微波Ⅲ型爆发，估计了双向电子束起源的频率和高度，3个事件分别揭示了在正向和反向漂移爆发之间的分界频率（约为250，1300和2900MHz),它们指出了一个致密的电子加速源，在这个源中产生了向上和向下两个方向注入的电子束，从这些事例可以表明不同事件的双向电子束的分界频率有一个相当大的范围（250－2900MHz)，而它们的起源范围却是在一个很小的（大约4－100MHz)和不同的频段范围内。最后讨论了日冕磁结构的拓扑范围、电子加速源构造的空间尺度、电子束运动速度和对偶Ⅲ型爆发的产生机制。 相似文献
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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... 相似文献
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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. 相似文献
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P. Maltby 《Solar physics》1972,26(1):76-82
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. 相似文献
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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. 相似文献
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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. 相似文献
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