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991.
J. E. Wink W. J. Altenhoff J. Bieging B. Butler H. Butner C.G.T. Haslam E. Kreysa R. Martin R. Mauersberger J. McMullin D. Muders W. Peters J. Schmidt J. B. Schraml A. Sievers P. Stumpff A. Von Kapp-Herr C. Thum R. Zylka 《Earth, Moon, and Planets》1997,77(3):165
The concept of simultaneous multifrequency continuum observations, successfully tested on Comet Hyakutake, was applied to
Comet Hale-Bopp, using the Heinrich Hertz Submillimeter Telescope (HHT) with the four color bolometer between 250 and 870
GHz, the IRAM 30m telescope at 240 Ghz, the MPIfR 100-m telescope at 32 GHz, and the IRAM interferometer near 90 and 240 GHz.
Near-simultaneous measurements were done between February 15 and April 26, 1997, mainly concentrated in mid March shortly
before perigee of the comet.
The measurements gave the following preliminary results:
Interferometer detection of the nuclear thermal emission. If the signal at the longest interferometer spacing of 170 mis due
to thermal emission from the nucleus only, its equivalent diameter is ∼49 km. If, however, this signal contains a contribution
from a strongly centrally peaked halo distribution(e.g., r−2 density variation) the diameter may be as low as 35 km. The emission found interferometrically was always 5″ north and 0.1
sec east from the position predicted by Yeoman's solution 55.The comparison of the interferometric continuum emission with
the simultanously obtained molecular line observations (reported on this conference) shows the origin of the strongest line
emission concentrated on the nucleus. The 30-m observations show a radio halo with a gaussian FWHP of ∼11, corresponding to
a diameter of 11000 km at geocentric distance of 1.2 a.u.
A spectral index of ∼3.0 for the total signal, which may indicate a smaller mean particle size than for Hyakutake. Assuming
an average cometary density of 0.5 gcm−3, the mass contained in the nucleus is ∼1$#x2013;3 1019 g and 1012 g in the particle halo.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
992.
Michael A. Dopita Michiel Reuland Wil van Breugel Wim de Vries S. A. Stanford Huub Röttgering George Miley Bram Venemans Hy Spinrad Steve Dawson Arjun Dey Mark Lacy Daniel Stern Andrew Bunker 《Astrophysics and Space Science》2007,311(1-3):305-309
We present results from a Keck optical and near IR spectroscopic study of the giant emission line halos of the z>3 High Redshift Radio Galaxies (HiZRGs) 4C 41.17, 4C 60.07 and B2 0902+34. The outer regions of these halos show quiet kinematics
with typical velocity dispersions of a few hundred km s−1 and velocity shears consistent with rotation. The inner regions contain shocked, clumpy cocoons of gas closely associated
with the radio lobes with disturbed kinematics and expansion velocities and/or velocity dispersions >1000 km s−1. We also find evidence for the ejection of chemically enriched material in 4C 41.17 up to a distance of ∼60 kpc along the
radio-axis. We infer that these HiZRGs are undergoing a final jet-induced phase of star formation with the ejection of most
of their interstellar medium before evolving to become “red and dead” Elliptical galaxies. 相似文献
993.
杨光崇 《成都信息工程学院学报》2002,17(3):222-226
借助L[a,b]空间和选择收敛好列的对角线法则,研究了一类显含一阶导数的二阶奇异边值问题非C^1正解的存在性和唯一性。 相似文献
994.
Jehin Emmanuel Boehnhardt Hermann Sekanina Zdenek Bonfils Xavier Schütz Oliver Beuzit Jean-Luc Billeres Malvina Garradd Gordon J. Leisy Pierre Marchis Franck Más Antonio Origlia Livia Scarpa Daniel Thomas Daniel Tozzi Gian Paolo 《Earth, Moon, and Planets》2002,90(1-4):147-151
Comet C/2001 A2 experienced several splitting events duringits 2001 perihelion passage. The first break-upevent was observed
in March 2001 (IAUC 7616).In this paper we report the first results of ourextensive imaging and spectroscopic monitoring campaignwith
ESO telescopes over several weeks before andafter the perihelion passage on May 25 2001. 相似文献
995.
We present the results of polarimetric and photometricobservations of split Comet C/2001 A2 (LINEAR), which wereobtained at
the 70-cm telescope of the Astronomical Observatoryof Kharkiv National University between 30 June and 31 July 2001.The brightest
fragment of the comet, nucleus B, was observed.Eight narrowband cometary filters in the continuum and in emissionbands and
a wideband red filter have been used. The comet wasobserved through apertures of 88, 33, and 19 arcsec. Polarizationphase
curves were obtained for the continuum and for the firsttime, for NH2(0, 7, 0) emission. The degree of polarization ofthe light scattered by the dust decreases with the increase ofaperture size.
An important temporal variation of the polarizationwith a rotation of the polarization plane was observed at twophase angles
(26.5° and 36.2°). Molecular column densities and production rates of CN, C2,C3, and NH2 species are calculated in the framework of theHaser model. A comparative analysis of the temporal variations ofthe visual
magnitudes, gas and dust production rates, dust colorand polarization are presented. 相似文献
996.
运用与本系列第一篇文章相同的设备与方法对PKS0349—27、3C98与PKS0634—20于1988年1月23—25日进行了观测。结果发现:PKS0349—27星系外缘突出物全部显现有向顺时针方向倾斜的趋势。3C98的延伸物主要向东北方向延伸。PKS0634—20的延伸物沿南北方向伸出,主要向北。 相似文献
997.
998.
介绍了一种在PLD(可编程逻辑器件)设计中引入原本用在模拟电子系统中反馈的概念,利用输出信号来控制输入信号,从而得到最小的系统时延的反馈算法,使器件性能得到最大优化. 相似文献
999.
动态数组在 C 程序设计中有广泛的应用,许多实现包括V C 6.0中附带的vector(向量)都只是动态内建类型数组的实现.由有显式构造/析构函数的对象元素(通常含有指针成员数据)构成的动态对象数组的高效实现则不是很容易,在深入分析C/ C 内存操作的基础上,给出了在 VC 6.0下动态对象数组的两种实现,并就构造/析构函数被调用的总次数等参数做了性能分析. 相似文献
1000.
Primary production was estimated over the annual cycle from 14C incubations conducted in 5 m deep enclosures and modeled for 16 stations in Narragansett Bay with data from biweekly surveys in which light, chlorophyll, attenuation coefficients and other parameters were measured. Annual values ranged from 160 g C m−2 y−1 in the lower West Passage to 619 g C m−2 y−1 at the mouth of the Providence River. The annual bay-wide, area mean fell near the middle of this range at 323 g C m−2 y−1 and was not apparently different from previous surveys. In the 1998 warm, El Niño winter, no bay-wide winter–spring phytoplankton flowered. Bloom limitation was correlated with warm temperatures which may have stimulated grazing rates. The lack of a bloom did not change annual levels of primary production but this alteration in carbon flow may impact macrofauna in the benthic infauna community. 相似文献