共查询到20条相似文献，搜索用时 46 毫秒
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在大量的 H_α边缘耀斑电影胶卷中,为了精炼起见我们选取了15套.电影胶卷是在1959年—1960年期间用紫金山天文台的利奥型色球望远镜拍摄的.边缘耀斑的光度和定位测量得出下列结果:(1)在耀斑的闪光阶段存在着剧烈的径向物质抛射,常常耀斑的一部分被抛射到色球层之上高达2·10~4公里到2.5·10~5公里处.(2)抛射的平均速度是30公里/秒—400公里/秒的数量级,最大的速度出现在抛射的初始阶段,抛射的加速度是超引力的.(3)耀斑的抛射运动是有规则的,且明显地与活动区的磁场有关.(4)在耀斑闪光阶段,抛射速度直接地随亮度增加的速率而变化.最后,注意到了射电事件的出现与抛射密切有关. 相似文献
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利用最小二乘法拟合了1995年1月至2001年9月Wind卫星观测到的行星际磁通量绳。根据拟合所得磁通量绳的直径,分析了行星际磁通量绳在这段时间内的发生率随磁通量绳直径D变化的关系,发现磁通量绳的发生率P(D)随直径D的变化可近似以幂律形式表示为:P(D)≈64D-0.768。行星际磁通量绳的发生率相对其直径的幂律分布表明所有行星际磁通量绳很可能是同一类现象且有共同的源,即它们都是太阳上日冕物质抛射的行星际对应物,只不过小尺度的磁通量绳对应较小的日冕物质抛射。最后,对行星际磁通量绳、日冕物质抛射和太阳耀斑的可能关系做了讨论。 相似文献
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本文主要介绍了1989年8月16、17日用本台太阳光谱仪的狭缝监视装置拍摄的AR5629活动区边缘Hα色球局部放大像系列资料概况。 16日拍摄到2N级耀斑的初相、极大以及耀斑冲浪,冲浪以50—180km/s的速度将物质抛出日面之外。随着耀斑面积增大,其形状也随着变化,可以看到有多层次环状 相似文献
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统计分析了23周太阳活动峰年期间(1998．12～2002.12)记录到的米波Ⅱ型爆发,与Ha耀斑和日冕物质抛射(CME)事件的关系。统计发现：持续时间长的Ha耀斑和CME与Ⅱ型爆发比与Ⅲ型爆发的相关性好;伴随Ⅱ型爆发的CME可发生在Ha耀斑之前或之后,且91％的长寿命耀斑发生在CME之前。平均在前23分钟;伴随Ⅱ型爆发的Ha耀斑的能量随着CME的速度增大而变强。对这些观测特征作了定性的解释。 相似文献
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本文介绍了１９９１年３月５日一个与３Ｎ级光学耀斑伴生的喷泉状爆发日珥。用Ｈα线观测从开始到结束整个过程共持续约５０分钟时间，日珥的最大投影高度１５．９万公里，视向速度分布表明，日珥主要以较大的速度向着观测者的运动，最大速度每秒１２０公里。 相似文献
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依据卫星和地面的观测数据,分析了峰值流量达到或超过10 000 pfu(1 pfu=1proton.cm~2.s~(-1).sr~(-1))的超强太阳质子事件相伴的太阳耀斑、曰冕物质抛射(CME)驱动激波的曰地传播速度、源区的曰面经度、卡林顿经度以及相伴的磁暴等现象.研究表明,超强太阳质子事件源区的曰面经度范围为E30°Longitude≤W75°.超强太阳质子事件源区分布在2个卡林顿经度带,分别为130°~220°的区域和260°~320°的区域.超强太阳质子事件都伴随着强烈的太阳耀斑和快速CME,CME驱动的激波从太阳到地球的平均速度超过1200 km/s.除一个超强太阳质子事件相伴的磁暴略低于强磁暴外,其余8个都伴有Dst≤-100 nT的强烈磁暴. 相似文献
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《中国天文和天体物理学报》2014,(10)
正Research in Astronomy and Astrophysics publishes original research papers and reviews on all branches of astronomy and astrophysics.Reviews are by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length to 6 printed pages).Authors who submit a paper are expected to be able to certify that the paper is original work, 相似文献
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Laura Schaefer 《Icarus》2005,173(2):454-468
We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10−6 to 10+1 bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I2 (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F. 相似文献
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《中国天文和天体物理学报》2014,(9)
正Research in Astronomy and Astrophysics publishes original research papers and reviews 011 all liranchcs of astronoiriy and astrophysics.Reviews arc by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length 相似文献
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Li Xin-nan Zhang Hai-ying Cui Xiang-qun Jiang Zi-bo Zheng Yi Liu Xing-tao Ni Hou-kun 《Chinese Astronomy and Astrophysics》2012
A special stressed annular polishing technique is proposed to mill the off-axis aspheric sub-mirrors of a large segmented mirror with an annular polishing machine. Based on the basic principle of stressed annular polishing technique, a set of special stressing mechanisms are designed to convert milling the aspheric surfaces of sub-mirrors with different off-axis distances into milling the spherical surfaces with identical radii of curvature, so that they can be pol- ished simultaneously on a continuous polishing machine. It took about contin- uous 40 hours to polish a scaled-down mirror of the planning Chinese Future Giant Telescope (CFGT) using this technique. This mirror has the 330 mm di- ameter, 3.6 m off-axis distance, and the 21.6 m radius of curvature, and its max- imum asphericity is 16 micron. The experiment shows that this method has a high effciency, suits batch manufacturing, especially the batch manufacturing of aspheric sub-mirrors of the segmented primary mirror of an extremely large aperture telescope. 相似文献
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Yehouda Enzel Rivka Amit Uri Dayan Onn Crouvi Ron Kahana Baruch Ziv David Sharon 《Global and Planetary Change》2008,60(3-4):165-192
Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant. 相似文献
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Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236
Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar
environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better
constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the
importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells.
Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The central compact object for some gamma-ray bursts (GRBs) may be a strongly magnetized millisecond pulsar. It can inject energy to the outer shock of the GRB by through the magnetic dipole radiation, and therefore causes the shallow decay of the early afterglow. Recently, from a large number of GRB X-ray afterglows observed by Swift/XRT(X-ray telescope), it is revealed that many of them exhibit the shallow decay about 102∼104 s after the burst prompt emission. We have fitted the X-ray afterglow light curves of 11 GRBs by using the energy injection model of a magnetar with the rotation period in the millisecond order of magnitude. The obtained result shows the validity and universality of the magnetar energy injection model in explaining the shallow decay of afterglows, and simultaneously provides some constraints on the magnetic field strength and rotation period of the central magnetar. 相似文献