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1.
大质量分子云核的CO同位素搜寻 总被引：1，自引：0，他引：1
使用紫金山天文台 １３．７ ｍ望远镜上新安装的 ＳＩＳ系统,对 ６４个高色指数 ＩＲＡＳ源和水脉泽源进行了 ＣＯ同位素１３ＣＯ和 Ｃ１８Ｏ Ｊ＝ １－０的搜寻,并对部分源作了成图观测．结果在 ６４个源中全部测到了这一谱线对,而１３ＣＯ的辐射一般较强,说明与稠密分子区成协,其中约６０个源为首次作ＣＯ同位素谱线对巡测．用高斯拟会导出了天线温度、线心速度和谱线全半宽．对辐射强度、话线特征进行了初步分析． 相似文献
2.
用射电天文联合实验室紫金山天文台青海站１３．７米望远镜，于１９９７年４月对９７个水脉泽源做了ＣＯ（Ｊ＝１－０）的巡测及部分成图观测，结果表明８１个源的谱线适于作成协星体活动分析．经初步证认有外向流候选者３３个，全部为首次给出高速范围．对其轮廓特点及与Ｈ２Ｏ脉泽辐射的关系作了简要讨论．ＣＯ高速气体和Ｈ２Ｏ脉泽的速度范围和峰值速度在多数情况下分别相符，这说明两者的激发可能相关． 相似文献
3.
使用紫金山天台１３．７ｍ望远镜上新安装的ＳＩＳ系统,对６４个高色指数ＩＲＡＳ源和水脉泽源进行了ＣＯ同位素＾１３ＣＯ和Ｃ＾１８ＯＪ＝１－０的搜寻,并对部分源作了成图观测,结果在６原中全部测到了这一谱线对,而＾１３ＣＯ的辐射一般较强,说明与稠密分子区成协,其中约６０个源为首次作ＣＯ同位素谱线对巡测,用高期拟合导出了天线温度、线心速度和谱线全半宽,对辐射强度、谱线特征进行了初步分析。 相似文献
4.
本文利用红外天文卫星点源表及哈勃望远镜导星星表对１９９０年新发表的７５个Ｓ星进行了ＩＲＡＳ红外源及ＧＳＣ光学对应体的证认，给出４１个Ｓ星有ＩＲＡＳ对应体，１２个Ｓ星有ＧＳＣ光学对应体。 相似文献
5.
6.
利用碳星星表（ＧＣＧＣＳ）、红外天文卫星（ＩＲＡＳ）点源表（ＰＳＣ）、哈勃望远镜（ＨＳＴ）导星星表（ＧＳＣ）及美国海军天文台星表（ＵＳＮＯ）对现今已知的２２个硅酸盐碳星重新进行了交叉证认,给出它们的确切位置,以利于今后进一步的观测研究,同时也指出其中存在值得怀疑的对象 相似文献
7.
使用青海站１３．７米射电望远镜对该望远镜发现的新的水脉泽源进行ＣＯ（Ｊ＝１－０）的观测。本文给出了其中尚未在文献中报道过ＣＯ观测结果的８个源的ＣＯ（Ｊ＝１－０）谱线，并对该观测结果进行了讨论。 相似文献
8.
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
9.
用紫金山天文台青海站的１３７ｍ射电望远镜对２７个强ＩＲＡＳ远红外源（流量Ｆ１００μｍ５００Ｊｙ）进行了ＣＯ（１－０）的谱线观测．观测表明,２７个强ＩＲＡＳ源全部与分子云成协,并与大质量星的形成或早期演化有关．其中１３个源是第一次给出ＣＯ（１－０）的谱线测量结果．本文对这一类源ＣＯ发射的性质进行了简单的讨论． 相似文献
10.
用紫金山天文台青海站的１３７ｍ射电望远镜,对１０个行星状星云给出了新的ＣＯ（１－０）谱线观测结果．其中４个行星状星云：ＮＧＣ６４４５,Ｍ１５９,Ｍ４９和Ｍ２５１,已有过ＣＯ（２１）的观测,本文第一次给出了它们的ＣＯ（１０）的测量结果;对２个别人曾经观测过但未测到ＣＯ的行星状星云：Ｓｈ２７１和Ｍ４１８,本文第一次证认了它们的ＣＯ发射;对４个别人从未进行过ＣＯ搜寻的行星状星云：ＶＶ１８,Ｍ２５２,Ｈｅ２４５９和Ｋ３３１,本文第一次进行了观测,并得到了它们的ＣＯ（１０）谱．由ＣＯ的发射谱征可见,ＶＶ１８可能是一个误分类的行星状星云 相似文献
11.
From the IRAS-PSC, 97 sources with steep FIR spectrum and another 8 were chosen for a search for high-velocity gas. Observations of the CO (J =1−0) line were made with the 13.3-m telescope at the Qinghai Station. The results show that 102 sources are associated with molecular gas. 9 of the sources have reference position problem and 21 have multiple spectrum. Of the remaining 72, 29 contain high-velocity gas, and of these 18 are new molecular outflow candidates. Their properties are discussed briefly in connection with massive young stellar objects. 相似文献
12.
The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources, the 10TeV γ-ray radiation reported by HESS, has been suggested as having a hadronic origin when relativistic protons are injected into and interact with the dense ambient gas. Assuming that such relativistic protons required by the hadronic model come from the tidal disruption of a star by the massive black hole of Sgr A*, we explore the spectrum of the relativistic protons. In the calculations, we investigate cases where different types of stars are tidally disrupted by the black hole of Sgr A*, and we consider that different diffusion mechanisms are used for the propagation of protons. The initial energy distribution of the injected spectrum of protons is assumed to follow a power-law with an exponential cut-off, and we derive the different indices of the injected spectra for the tidal disruption of different types of stars. For the best fit to the spectrum of photons detected by HESS, the spectral index of the injected relativistic protons is about 2.05 when a red giant is tidally disrupted by the black hole of Sgr A* and the diffusion mechanism is the Effective Confinement of Protons. 相似文献
13.
《New Astronomy Reviews》2002,46(2-7):121-134
X-ray emission traces the gaseous environments of radio sources. The medium must be present for jet confinement, but what are its influence on jet fueling, dynamics, propagation, and disruption? The observational situation is both complicated and enriched by radio sources being multi-component X-ray emitters, with several possible regions of non-thermal emission. Recent work, primarily based on sensitive ROSAT pointings, is used to contrast the X-ray emission and environments of radio sources with: (a) low power, (b) high power at high redshift, (c) high power at lower redshift, and (d) GHz peaked spectrum emission. The trends in external gas density and pressure near extended radio structures are reviewed. Imminently-available X-ray measurements with vastly improved resolution and sensitivity have great potential for resolving many open issues. 相似文献
14.
The distribution of X-ray sources in our galaxy is obtained, assuming that the absolute X-ray luminosities of these sources are the same. The distribution is found to be in good correlation with the distribution of interstellar gas. The density of X-ray sources is nearly proportional to the square density of gas. This indicates that X-ray sources are comparatively young. The relation between the densities of X-ray sources and gas allows us to estimate the X-ray intensities of various objects such as Magellanic Clouds and Andromeda nebula, and also to obtain the average X-ray luminosity of spiral galaxies. The latter should increase as the age of a galaxy decreases, since the amount of gas decreases as the galaxy evolves. Under the assumptions that the gas density is inversely proportional to the age and that galaxies older thant
0/30 are visible in X-rays, wheret
0 is the present age of the universe, the contribution of X-ray sources in distant galaxies to the background component is calculated. The intensity and the spectrum of the background component of X-rays thus obtained are in fair agreement with observed ones in the energy range between 1 and 4 keV but significantly deviate from the latter at high energies. 相似文献
15.
P. Thomasson D. J. Saikia T. W. B. Muxlow 《Monthly notices of the Royal Astronomical Society》2003,341(1):91-99
Multifrequency radio observations of the radio galaxy 3C 459 using MERLIN, VLA and the EVN and an optical Hubble Space Telescope ( HST ) image using the F702W filter are presented. The galaxy has a very asymmetric radio structure, a high infrared luminosity and a young stellar population. The eastern component of the double-lobed structure is brighter, much closer to the nucleus and is significantly less polarized than the western one. This is consistent with the jet on the eastern side interacting with dense gas, which could be due to a merged companion or dense cloud of gas. The HST image of the galaxy presented here exhibits filamentary structures and is compared with the MERLIN 5-GHz radio map. EVN observations of the prominent central component, which has a steep radio spectrum, show a strongly curved structure suggesting a bent or helical radio jet. The radio structure of 3C 459 is compared with other highly asymmetric, Fanaroff–Riley II radio sources, which are also good candidates for studying jet–cloud interactions. Such sources are usually of small linear size and it is possible that the jets are interacting with clouds of infalling gas that fuel the radio source. 相似文献
16.
Giant radio galaxies are the most extended radio sources in the universe having the sizes of groups and clusters of galaxies
(about 1 Mpc). Their total number is comparable with the amount of clusters, revealing the Zeldovich-Sunyaev effect, which
may lead to a biased estimation of the angular power spectrum for the ZS effect. To assess a possible contribution to the
power spectrum, we need to collect the data on all the observed giant radio galaxies. We propose an algorithm for the selection
of large sources (sized over 4′) from the NVSS survey catalog, using the parameters of possible components of radio sources,
cataloged as compact objects. As a result of the first stage of our work, we have selected 61 new giant radio galaxy candidates,
of which 35 have a pronounced morphological type FRII, and 26 galaxies—the FRI type. 相似文献
17.
We present calculations of the dynamics of highly ionized gas (HIG) clouds that are confined by external pressure, and are photoionized by AGN continuum. We focus on the gas that is seen, in absorption, in the X-ray spectrum of many AGN and show that such gas can reach hydrostatic equilibrium under various conditions. The principal conclusion is that the clouds can be accelerated to high velocities by the central X-ray source. The dynamical problem can be reduced to the calculation of a single parameter, the average force multiplier, 〈 M 〉. The typical value of 〈 M 〉 is ∼10 suggesting that radiation pressure acceleration by X-rays is efficient for L / L Edd ≳0.1 . The terminal velocity scales with the escape velocity at the base of the flow and can exceed it by a large factor. The typical velocity for a HIG flow that originates at R =1017 cm in a source with L x =1044 erg s−1 is ∼1000 km s−1 , i.e. similar to the velocities observed in several X-ray and UV absorption systems.
Highly ionized AGN clouds are driven mainly by bound–free absorption, and bound–bound processes are less important unless the lines are significantly broadened or the column density is very small. Pressure laws that result in constant or outward decreasing ionization parameters are most effective in accelerating the flow. 相似文献
Highly ionized AGN clouds are driven mainly by bound–free absorption, and bound–bound processes are less important unless the lines are significantly broadened or the column density is very small. Pressure laws that result in constant or outward decreasing ionization parameters are most effective in accelerating the flow. 相似文献
18.
用紫金山天文台青海观测站１３７ｍ射电望远镜对Ｓ１４６和ＩＲＡＳ２３５４５＋６５０８进行了１２ＣＯ（Ｊ＝１－０）谱线的成图观测,结果表明两源附近存在ＣＯ高速外向流．分析了这两个外向流的形态,求出了其物理和动力学参数,同时结合ＩＲＡＳ资料,对中心源的演化阶段和环境气体的热特性作了分析． 相似文献
19.
Carl BlaksleyEtienne Parizot 《Astroparticle Physics》2012,35(6):342-345
We study a generic class of models for ultra-high energy cosmic ray (UHECR) phenomenology, in which the sources accelerate protons and nuclei with a power-law spectrum having the same index, but with different values for the maximum proton energies, distributed according to a power-law. We show that, for energies sufficiently lower than the maximum proton energy, such models are equivalent to single-type source models, with a larger effective power law index and a heavier composition at the source. We calculate the resulting enhancement of the abundance of nuclei, and find typical values of a factor 2-10 for Fe nuclei. At the highest energies, the heavy nuclei enhancement ratios become larger, and the granularity of the sources must also be taken into account. We conclude that the effect of a distribution of maximum energies among sources must be considered in order to understand both the energy spectrum and the composition of UHECRs, as measured on Earth. 相似文献
20.
J. E. Dyson 《Astrophysics and Space Science》1984,106(1):181-197
Stellar winds interacting with gas in dense molecular clouds produce flows which may be initially energy or momentum driven. A criterion for this is derived which depends sensitively on the wind velocity. Flows may change from one regime to another depending on the gas distribution about the wind source and these changes are discussed for power law density distributions. In general, the flows observed in CO associated with infrared point sources seem to be in the energy driven regime. By combining CO observations with radio continuum flux measurements, wind parameters are derived for several of these sources. There is some evidence from the derived parameters that high (L
*2×103
L
) luminosity sources have radiatively-driven winds. Lower luminosity source winds are driven by some agency as yet unknow. We suggest that the widths of infrared lines from wind sources seriously underestimate the wind terminal velocities. 相似文献