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彗星Ｃ１９９７Ｌ１被改名为“朱－巴拉姆”彗星据１９９８年１月２３日国际天文学联合会快讯消息,由北京天文台观测宇宙学课题组于１９９７年６月３日发现的彗星Ｃ１９９７Ｌ１被重新命名为“朱－巴拉姆”彗星。这一决定是国际天文学联合会小天体命名委员会为了确定... 相似文献
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用紫金山天台青海站的１３．７ｍ射电望远镜,对１０个行星关星云给出了新的ＣＯ（１－０）谱线观测结果。其中４个行星关星云：ＮＧＣ６４４５,Ｍ１－５９,Ｍ４－９和Ｍ２－５１,已有过ＣＯ（２－１）的观测,本第一次给出了它们的ＣＯ（１－０）的测量结果;对２个别人曾经预测过但未测到ＣＯ的行星状星云：Ｓｈ２－７１和Ｍ４－１８,本第一次证认了它们的ＣＯ发射;对４个别人从未进行ＣＯ搜寻的行星状星云：Ｖ－Ｖ１－ 相似文献
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Ｃｏｍｐｔｏｎγ射线望远镜ＣＯＭＰＴＥＬ／ＣＧＲＯ工作于０．７５－３０ＭｅＶ能区，本文应用直接解调方法分析ＣＧＲＯ＃１观测的ＣＯＭＰＴＥＬ数据，准确定出Ｃｒａｂγ射线源的位置，在１０－３０ＭｅＶ能区，分辨开最大似然法所不能完全分辨的Ｃｒａｂγ射线源和类星体ＰＫＳ０５２８＋１３４，得出优于传统成像方法所得的成像结果．应用直接成像方法处理γ射线脉冲星Ｇｅｍｉｎｇａ分位相数据，发现Ｇｅｍｉｎｇａ在１０－３０ＭｅＶ能区仍存在辐射，辐射集中在Ｇｅｍｉｎｇａ第一个峰的位相区域．结果表明，应用直接解调方法对Ｃｏｍｐｔｏｎ望远镜数据作成像分析是完全可行的 相似文献
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Comptonγ射线望远镜的直接解调成像 总被引：2，自引：0，他引：2
Ｃｏｍｐｔｏｎγ射线望远镜ＣＯＭＰＴＥＬ／ＣＧＲＯ工作于０．７５－３０ＭｅＶ能区，本应用直接解调方法分析了ＣＧＲＯ＃１观测的ＣＯＭＰＴＥＬ数据，准确定出Ｃａｒａｂγ射线源的位置，在１０－３０ＭｅＶ能区，分辨开最大似然法所不能完全分辨的Ｃｒａｂγ射线源和类星体ＰＫＳ０５２８＋１３４，得出优于传统成像方法所得的成像结果。 相似文献
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利用紫金山天文台青海站的 １３．７ ｍ毫米波望远镜,对 Ｏｒｉｏｎ Ａ分子云中的 ＯＭＣ－３区域,进行了较高分辨率的１３ＣＯ（Ｊ＝１－０）和Ｃ１８Ｏ（Ｊ＝１－０）分子辐射的成图观测．给出了该分子云中１３ＣＯ和 Ｃ１８Ｏ云核分布的整体结构和平均物理参数．观测发现,该分子云的１３ＣＯ和 Ｃ１８Ｏ的云核中心分别与最年轻的天体－Ｃｌａｓｓ ０类源 ＭＭＳＩ, ＭＭＳ４,ＭＭＳ６和ＭＭＳ７,ＭＭＳ８;ＭＭＳ９成协．此外,通过分析ＯＭＣ－３整个区域的速度场结构,发现沿 Ｃ１８Ｏ和１３ＣＯ云核方向从南到北有一个～ １．７ｋｍ／ｓ的速度场梯度,而分子云的红、蓝移团块则分别趋于云的北部和南部．并对ＯＭＣ－３区的恒星形成特征进行了讨论． 相似文献
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利用紫金山天台青海站的１３．７ｍ毫米波望远镜,对ＯｒｉｏｎＡ分子云中的ＯＭＣ－３区域,进行了较高分辨率的＾１３ＣＯ（Ｊ＝１－０）和Ｃ＾１８Ｏ（Ｊ＝１－０）分子辐射的图观测,给出了该分子云中＾１３ＣＯ和Ｃ＾１８Ｏ的云核中心分别与最年龄的天体－Ｃｌａｓｓ０类源ＭＭＳＩ,ＭＭＳ４,ＭＭＳ６和ＭＭＳ７,ＭＭＳ８,ＭＭＳ９成协,此外,通过分析ＯＭＣ－３整个区域的速度场结构,发现沿Ｃ＾１８Ｏ和＾１３ＣＯ云核 相似文献
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CO67—186μm谱线在天体物理研究中的作用 总被引：1，自引：0，他引：1
采用球型大速度梯度模型,对ＩＲＣ＋ １０２１６ 、ＡＦＧＬ２６８８ 和ＮＧＣ７０２７ 等经ＩＳＯ 发表的首次数据证明有相对强的ＣＯ６７ － １８６ μｍ 发射线的天体作模型计算．统计平衡辐射转移计算共覆盖低于能量４８６３ ｃｍ －１（ｖ ＝ ０ ,Ｊ＝ ０ 能级的能量为０） 的全部能级,即ｖ ＝ ０ 、Ｊ＝ ０ －５０ ,ｖ ＝ １ 、Ｊ＝ ０ － ３７ 和ｖ ＝ ２ 、Ｊ＝ ０ － １７ 的１０７ 个能级．计算表明ＣＯ 谱线的流量相对值对于上能级转动量子数Ｊｕ 的分布函数,是该谱线发射区物理条件的良好探针．ＩＲＣ＋ １０２１６ 的ＣＯ远红外发射线主要由中央星激发形成,而ＡＦＧＬ２６８８ 和ＮＧＣ７０２７ 区则是因温暖和致密的冲击气体所致．对ＩＳＯ 首次数据涉及的其他天体的ＣＯ 谱线激发机制,也作了一些讨论。ＣＯ 的谱线是在６７ － １８６ μｍ 波段探测动能温度数百度以上的热天体,诸如富碳、富氧演化星包层,行星状星云、年轻星和恒星形成区复合体物理条件的重要探针 相似文献
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对地方电视台转播CCTV时延的测定 总被引：1，自引：0，他引：1
讲述了同步广播卫星电视时间信号的测量方法和测量结果，获得了ＣＣＴＶ、ＣＣＴＶ２通过同一颗卫星（亚太－１Ａ）转播的时延差值为１６３．３３μｓ，测量精度在１０ｎｓ以内；ＣＣＴＶ２、ＣＣＴＶ４分别经两颗卫星（亚太－１Ａ，亚洲－Ⅱ）转播，在陕西天文台卫星地面接收站时延差值为１６４４．２０μｓ，严谨为５０μｓ，并分析了影响时延差值和精度的原因，同时测量了地方电视台转播亚太－１Ａ的ＣＣＴＶ信号与直接接收亚太－ 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