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1.
利用甚长基线干涉仪，在１６６５ＭＨｚ频率上，观测超致密氢ＩＩ区Ｇ４５．０７＋０．１３的左右圆偏振羟基（ＯＨ）分子脉泽辐射．利用多条纹率成图方法，获得了这个区域２０ｍａｓ相对位置精度的脉泽结构图．除两个弱子源以外，所有脉泽子源都位于彗状结构氢ＩＩ区“彗头”的前沿．脉泽团离致密氢ＩＩ区中心投影距离为０＂．４．在完全饱和辐射的假设下，估计脉泽活动区具有氢分子数密度约为４．５×１０８（Ｈ２）ｃｍ－３．在脉泽源中，发现一对Ｚｅｅｍａｎ对，从它们的ＬＳＲ速度差，导出脉泽区的磁场约为３ｍＧ，方向为远离地球方向．在致密氢ＩＩ区Ｇ４５．０７＋０．１３彗头附近的脉泽团的直径为６×１０１６ｃｍ．这与Ｇ３４．０３＋０．２的观测结果很类似．这给解释彗状结构的氢ＩＩ区的各种模型提供了一个可靠的观测约束条件． 相似文献
2.
本文给出３５个不同类型含ＳｉＯ（ｖ＝１,Ｊ＝１－０）脉泽发射的ＡＧＢ星的近红外观测结果（其中包括６个Ⅰ型ＯＨ星,１３个Ⅱ型ＯＨ星,９个仅有ＳｉＯ脉泽的星以及７个无ＯＨ脉泽但有ＳｉＯ和Ｈ２Ｏ脉泽的星）．得出了它们的ＪＨＫ星等和流量．同时经认证找出了它们对应的ＩＲＡＳ观测数据．通过对它们的近红外、中远红外以及ＯＨ射电资料的同时分析,得出了不同类型ＳｉＯ脉泽星的色指数、谱斜率以及在近红外波段上拟合的等效黑体温度Ｔｅｑ．由红外及ＯＨ射电资料导出了其中心星的质量损失率Ｍ,并在此基础上结合已知的ＳｉＯ脉泽源资料,找出了不同类型ＳｉＯ脉泽星各量之间的关系．计算结果表明,ＳｉＯ脉泽具有普遍性,在各类脉泽星中都可出现．ＳｉＯ脉泽的光度与质量损失率弱相关,并且从（Ｍｉｒａ）ＳｉＯ到（ＯＨ／ＩＲ）ＳｉＯ逐渐增加．ＳｉＯ脉泽的流量与近红外“色”以及等效黑体温度Ｔｅｑ的关系较为密切．ＳｉＯ脉泽积分流量的上限与ＩＲＡＳ在１２μｍ和２５μｍ上流量分别都相关．本文对ＳｉＯ脉泽在ＡＧＢ演化中的地位和特殊性进行了简单讨论． 相似文献
3.
ON2中部区域OH1667MHz脉泽的新观测 总被引：1，自引：0，他引：1
利用法国巴黎默东天文台的南锡射电望远镜对ＯＮ２ 中部区域ＯＨ１６６７ ＭＨｚ 脉泽首次进行观测．观测结果表明中部区域的ＯＨ１６６７ ＭＨｚ 脉泽的辐射频谱为典型的双峰结构．这说明ＯＮ２ 中部区域的ＯＨ１６６７ ＭＨｚ 脉泽是位于绕中央星运动的薄盘上．结合模型对中部区域的ＯＨ１６６７ ＭＨｚ 脉泽谱线频谱图进行分析和研究 相似文献
4.
5.
本项研究给出了17个具有Ⅱ类星际甲醇分子脉泽源的致密氢11区的轫致辐射、尘埃红外辐射和中心年轻恒星Layman辐射的特征．以脉泽的光子发射率和辐射亮温度作为两个主要的辐射抽运约束条件，讨论了Ⅱ类星际甲醇分子脉泽的几种可能的激发机制．我们认为热辐射亮温度为100K与致密氢Ⅱ区成协的红外辐射体很可能是Ⅱ类甲醇脉泽的抽运源． 相似文献
6.
使用澳大利亚Ｐａｒｋｅｓ６４ｍ射电望远镜,在五个不同的位置上观测了ＯＨ１７．７２．０附近的弱ＯＨ脉泽源．发现了一个新的弱ＯＨ脉泽源,其峰值速度为５２．５ｋｍ／ｓ．利用二维Ｇａｕｓｓｉａｎ拟合技术,得到了这个源的最佳拟合位置 相似文献
7.
通过对 Ｗ３（ＯＨ）区域 ２２ ＧＨz Ｈ_(２)Ｏ脉泽源的短时间跟踪观测,探测到速度为-５２．８ ｋｍ／ｓ子谱的流量密度呈线性下降趋势,变化时标约为 １９天．同时也观测到了整个脉 泽源的谱线宽度与该子谱的强度之间的相关变化．这些现象可能是由脉泽云之间的相 互碰撞导致脉泽抽运率的变化所引起的。 相似文献
8.
通过对Ｗ３（ＯＨ）区域２２ＧＨzＨ２Ｏ脉泽源的短时间跟踪观测,探测到速度为－５２ ．８Ｋｍ／ｓ子谱的流量密度呈线性下降趋势,变化时村约为１９天。同时也观测到了整个脉泽源的谱线宽度与该子谱的强度之间的相关变化。这些现象可能是由脉泽云之间的相互碰撞导致脉泽抽运率的变化所引起的。 相似文献
9.
氢脉泽的支持电子学系统是氢脉泽频率标准中子学的一个重要组成部分，它包括脉泽的热控制、磁场控制、氢压以及调谐控制。本将介绍上海天台新近研制成功的新氢脉泽（H7）的支持电子学系统的各控制部分的设计思想及特点。 相似文献
10.
俞志尧 《中国天文和天体物理学报》1997,(2)
用多重分离的旋转膨胀环模型，分析了旋涡星系Ｍ３３的ＨＩＩ区复合体ＩＣ１３３中的１４个脉泽源斑的ＶＬＢＩ相对位置图，发现这１４个Ｈ２Ｏ脉泽源斑在ＨＩ区复合体盘上成环状，分布在二个不同的旋转膨胀盘环上．同时，也得到这１４个Ｈ２Ｏ脉泽源斑的运动学特性． 相似文献
11.
Josef Jochum 《Astronomische Nachrichten》2007,328(7):683-688
H86 Core‐Collapse Supernovae: Neutrinos, Explosion Mechanism, and Pulsar Kicks H141 Indirect Dark Matter Search In Dwarf Galaxies H143 Electrostatic spectrometers of KATRIN H144 The tritiumsource of KATRIN H146 Status of the KATRIN experiment H149 Axions in the CAST aera H151 The EDELWEISS‐2 Dark Matter Search H152 Simulation of muon‐induced neutron background in EDELWEISS H155 CRESST Status H161 A Trigger for the Double Chooz Reactor Neutrino Experiment H162 Status of GERDA – Neutrinoless Double Beta Decay H175 New Laboratory Experiments Searching for Axion‐Like Particles H178 Cosmic ray induced background at the KATRIN experiment and its prevention H201 The X‐ray telescope of the CAST experiment at CERN H238 Structure formation close to the cut‐off in the matter power spectrum 相似文献
12.
H01 A first glance at LOFAR: Experience with the Initial Test Station H02 The Square Kilometer Array (SKA) – Status and Prospects H03 LOFAR calibration: confrontation with real WSRT data H04 Simulations of magnetic fields in the cosmos H05 RM structure in the polarized synchrotron emission from our Galaxy and the Perseus cluster of Galaxies H06 Mapping the Reionization Era through the 21 cm Emission Line H07 Spiral galaxies seen with LOFAR H08 Software Infrastructure for Distributed Data Processing H09 The Low Frequency Array (LOFAR) – Status and Prospects H10 Coincident cosmic ray measurements with LOPES and KASCADE‐Grande H11 Radio relics in a cosmological cluster merger simulation H12 Detection of radio pulses from cosmic ray air showers with LOPES H13 Geosynchrotron radio emission from extensive air showers H14 Imaging capabilities of future radio telescopes H15 Digital signal processing system of Multi‐Beam Meter Wavelengths Array. H16 The Multi‐Beam Meter Wavelengths Array H17 Monitoring of the Solar Activity by LOFAR H18 Calibration of LOPES30 H19 An Outreach Project for LOFAR and Cosmic Ray Detection H20 Galactic tomography based on observations with LOFAR and Effelsberg H21 150 MHz observations with the Westerbork and GMRT radio telescopes of Abell 2256 and the Bootes field: Ultra‐steep spectrum radio sources as probes of cluster and galaxy evolution H22 Experience of simultaneous observations with two independent multi‐beams of the Large Phased Array H23 GRID Computing at Forschungszentrum Karlsruhe suitable for LOFAR 相似文献
13.
The syntheses of interstellar c-C3H2, H2CCC, c-C3H, and HCCC, where "c" stands for the cyclic isomer, are thought to proceed via dissociative recombination of the precursor ions c-C3H3+ and H2CCCH+, which are themselves produced mainly via the radiative association reaction between C3H+ and H2. We have utilized ab initio methods to study the potential energy surface (PES) for the association of the linear ion C3H+ and H2 to form the isomers c-C3H3+ and H2CCCH+. The overall rate coefficient for radiative association has been calculated as a function of temperature via the phase space method. Our ab initio calculations show that the H2CCCH+ isomer is formed directly without an activation barrier from reactants, and that isomerization between the two isomers can occur readily via a low-energy pathway consisting of two transition states (saddle points on the PES) and one intermediate (local minimum on the PES). Calculations of the equilibrium coefficient for the isomerization H2CCCH+ <-> c-C3H3+ as a function of energy shows that equal abundances of these two ions should be produced as relaxation proceeds, in agreement with experimental measurements at high pressure. Our results confirm the important point that a simple ion-molecule association reaction can produce a cyclic hydrocarbon. If dissociative recombination reactions involving c-C3H3+ and H2CCCH+ maintain the carbon skeletal structure of the ions and produce roughly similar C3H/C3H2 branching ratios, then abundance ratios of unity are produced between the cyclic and noncyclic isomers of C3H and C3H2 via this mechanism. The large abundance ratio of c-C3H2 to H2CCC observed in TMC-1 can then be explained by differential destruction rates. 相似文献
14.
The observed ratio of C2H6 to C2H2 in the Jovian stratosphere increases from approximately 55 at 2 mbar to approximately 277 at 12 mbar. In current photochemical models this ratio typically increases between 2 and 12 mbar by a factor of < or = 3. Recent laboratory kinetics studies on the reaction between C2H3 and H2 to form C2H4 suggest an efficient chemical mechanism for hydrogenation of C2H2 to C2H6. Inclusion of this scheme as part of a comprehensive updated model for hydrocarbon photochemistry in the atmosphere of Jupiter provides an explanation of the altitude variation of the C2H6/C2H2 ratio. The sensitivity of these results to uncertainties in the key rate constants at low temperatures is illustrated, identifying needs for additional laboratory measurements. Since the key reaction rate constants decrease with decreasing temperature, the hydrogenation of C2H2 as proposed predicts a qualitatively decreasing trend in the C2H6/C2H2 value with decreasing distance from the Sun. The observed variation between Jupiter and Saturn is consistent with this prediction. 相似文献
15.
Hot and cold deserts have been thoroughly searched for meteorites in the past decades, which has led to a large inventory of classified meteorites. H‐ and L‐chondrites are the most abundant meteorites in all collections, and many authors used the H/L ratio as a characteristic parameter in comparing meteorite populations. H/L ratios (after pairing) vary from 0.90 in observed falls up to 1.74 in El Médano (Atacama Desert). In this study, we investigate the H/L ratio of 965 unpaired H‐ and L‐chondrites collected in Oman and compare this population with observed falls and other hot desert collections. We find a mass dependence of the H/L ratio among hot desert finds and identify mechanisms such as fragmentation during weathering and fall that have an impact on the H/L ratio. We employ the Kolmogorov–Smirnov and Mann–Whitney U statistical tests to compare the mass distributions of H‐ and L‐chondrites and to test the relationship between the similarity of mass distributions and the H/L ratio. We conclude that the variations of the H/L ratios observed in various populations are a sampling artifact resulting from secondary effects and observational bias, expressed in differences of the H and L mass distributions which are not observed in falls, and not due to variations in H/L of the meteorite flux. The H/L ratio of 0.90 observed among recent falls is considered as most representative for the overall meteorite flux, at least since the Late Pleistocene. 相似文献
16.
In this work 13 Planetary Nebulae have been classified as Type I according to Peimbert's criteria (Peimbert, 1978). These objects have been added to a previous sample (Maciel and Faúndez-Abans, 1985) and diagrams of O/H versus N/H, S/H, Ne/H and Ar/H, as well as N/H versus S/H, Ne/H and Ar/H have been drawn. All of them exhibit a tendency for linear correlation; moreover, the behavior of O and N versus Ar and S are very similar, with approximately the same slope. When the excitation class parameter was included in the diagrams, no clear tendency can be discerned, for any class. 相似文献
17.
Abstract— To examine the thermal history of the parent body/bodies of equilibrated H chondrites, we treated data for 11 volatile trace elements (Co, Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl, and In in order of putative volatility) in 90 falls: 15 H4; 46 H5, and 29 H6. Using univariate statistical tests, contents of few of these elements differ significantly between any two of these suites. One element, Cs, differs systematically between all three pairs of suites; Co and Tl differ between two pairs of suites. For Co and Cs, contents varied as H4 > H5 > H6; while for Tl, contents varied as H4 < H5 < H6. Using multivariate statistical tests, all three suites can be distinguished compositionally, with trace element contents in the H5 suite being intermediate to those of H4 and H6. Surprisingly, the multivariate distinguishability reflects contents of less volatile Co, Rb, Ag, Se and Cs, and not of highly volatile Te, Zn, Cd, Bi, Tl and In. The compositional trends apparently reflect heterogeneous accretion >600 K, with the suites deriving from a stratified parent body/bodies. 相似文献
18.
H2 is the most abundant molecule in the universe. We demonstrate that this molecule may be an important component of interstellar and possibly intergalactic ices, both because it can be formed in situ, within the ices, and because gas phase H2 can freeze out onto dust grains in some astrophysical environments. The condensation-sublimation and infrared spectral properties of ices containing H2 are presented. We show that solid H2 in H20-rich ices can be detected by an infrared absorption band at 4137 cm-1 (2.417 micrometers). The surface binding energy of H2 to H2O ice was measured to the delta Hs/k = 555 +/- 35 K. Surface binding energies can be used to calculate the residence times of H2 on grain surfaces as a function of temperature. Some of the implications of these results are considered. 相似文献
19.
C. Esteban J. M. Vilchez A. Manchado M. G. Edmunds 《Astrophysics and Space Science》1989,157(1-2):3-7
We report on extensive spectroscopic observations of the WR-ring nebulae NGC 2359 and RCW 78, respectively, excited by the WN5 stars HD 56925 and WN8 HD 117688. For the first object we have determined abundances for O/H, Ne/H, N/H, and He/H in many different positions, including the ionized gas in the bubble, inside the optical shell structure, and the outermost zones associated with the S 298 Hii region. We do not find any significant difference in the N/H and O/H abundances over the entire nebula. The O/H and N/H abundances expected are close to those for a normal Hii region located at similar distance. In the case of He/H we find indication of local enhancements which sum to the abundance of metal rich galactic Hii regions like M17. RCW 78 appears to show slight overabundances of He/H and N/H in the two observed positions.The ionising temperature for the WN central star (HD 56925) of NGC 2359 is determined from the observed Hii region spectrum giving a value of 50000 K, appropriate to its spectral type. 相似文献
20.
Radial abundance gradients of the element ratios O/H, Ne/H, S/H, and Ar/H are determined for a sample of disk planetary nebulae,
emphasizing the behaviour of the gradients at large galactocentric distances.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献