上海光机所小喷泉铷钟的设计和进展

对上海光机所正在研制的小喷泉铷钟及目前正在进行的工作作了介绍.该小喷泉铷钟吸收了原子喷泉的许多新技术,采用紧凑的结构设计,加入空心光束以提高探测原子数.预期该喷泉的准确度为10-14,短、长稳分别为10-13和10-15,信噪比为103.实验室完成了冷原子物理的准备工作,已经俘获冷原子团.     

The AGN/Starburst connection in luminous infrared galaxies

We are addressing the issue of whether there exists an evolutionaryconnection between starburst and AGN in luminous infrared galaxies. We are combining theoretical modelling with optical, radio and infrared data from IRAS for a large sample of 285 infrared galaxies with a range ofluminosities. In this paper, we present a comparison between the optical spectroscopic data with the incidence of compact radio cores for a subsample of these galaxies. We find 90% of AGN type galaxies contain compact radio cores, while 37% of starburst galaxies contain compact radio cores. The compact radio cores in the starburst galaxies have a minimum brightness temperature of 3 × 10⁵ K, higher than those of standard extended HII regions and may be obscured AGN or complexes of extremely luminous supernovae such as that seen in Arp 220.     

The HST/ACS Coma Cluster Survey – V. Compact stellar systems in the Coma Cluster

The Hubble Space Telescope /Advanced Camera for Surveys ( HST /ACS) Coma Cluster Treasury Survey is a deep two-passband imaging survey of the nearest very rich cluster of galaxies, covering a range of galaxy density environments. The imaging is complemented by a recent wide field redshift survey of the cluster conducted with Hectospec on the 6.5-m Monolithic Mirror Telescope (MMT). Among the many scientific applications for these data is the search for compact galaxies. In this paper, we present the discovery of seven compact (but quite luminous) stellar systems, ranging from M32-like galaxies down to ultra-compact dwarfs (UCDs)/dwarf to globular transition objects (DGTOs).
We find that all seven compact galaxies require a two-component fit to their light profile and have measured velocity dispersions that exceed those expected for typical early-type galaxies at their luminosity. From our structural parameter analysis, we conclude that three of the samples should be classified as compact ellipticals or M32-like galaxies, and the remaining four being less extreme systems. The three compact ellipticals are all found to have old luminosity weighted ages (≳12 Gyr), intermediate metallicities  (−0.6 < [Fe/H] < −0.1)  and high [Mg/Fe] (≳0.25).
Our findings support a tidal stripping scenario as the formation mode of compact galaxies covering the luminosity range studied here. We speculate that at least two early-type morphologies may serve as the progenitor of compact galaxies in clusters.     

Relationship of galaxies from the second Byurakan survey to Zwicky clusters. II. Discussion

We analyze the data presented in a previous paper by Gyulzadyan and Petrosian, and discuss the results of a statistical investigation of the relationship between SBS galaxies and Zwicky clusters. The main results are that SBS galaxies follow the overall galaxy distribution in clusters and they do not avoid any type of Zwicky cluster. There is a significantly higher probability of finding SBS galaxies occurring in medium compact clusters than in open clusters. They also follow the well-established morphology-density relation. Earlier morphological type, higher luminosity, larger linear size, and redder SBS galaxies tend to be found in clusters with higher compactness, or in more compact regions of the clusters. The number distribution of SBS galaxies in Zwicky open clusters probably follows the distribution of normal galaxies. The number distribution of SBS galaxies in medium compact and compact clusters shows two-maxima structure. Published in Astrofizika, Vol. 52, No. 2, pp. 225–236 (May 2009).     

Accretion disc with dipole magnetic field in linearized Kerr Geometry

In this paper we discuss the equilibrium configuration of a plasma disc of infinite conductivity around a slowly rotating compact object, and obtain the pressure profiles, and the structure of magnetic field lines for co and counter-rotating discs.     

Extended emission associated with young H ii regions

We have used the Australia Telescope Compact Array (ATCA) to make observations of a sample of eight young ultra-compact H  ii regions, selected on the basis that they have associated class II methanol maser emission. We have made observations sensitive to both compact and extended structures and find both to be present in most sources. The scale of the extended emission in our sample is in general less than that observed towards samples based on IRAS properties, or large single-dish flux densities. Our observations are consistent with a scenario where extended and compact radio continuum emission co-exists within H  ii regions for a significant period of time.
We suggest that these observations are consistent with a model where H  ii evolution takes place within hierarchically structured molecular clouds. This model, which is the subject of an upcoming companion paper by Shabala et al., addresses both the association between compact and extended emission and the ultra-compact H  ii region lifetime problem.     

星际甲醇分子脉泽的辐射抽运研究

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．     

The youngest X-ray binaries

Several X-ray binaries(XRBs) have been identified to be associated with supernova remnants(SNRs). Because of the short lifetimes of SNRs, this leaves them to be the youngest known XRBs.This small group of binaries provides valuable information on the formation of compact stars under the framework of massive binary evolution. In this paper we review the observational characteristics of these youngest XRBs and discuss their possible implications on the initial conditions of compact stars and their interaction with the companion stars.     

On the stability of compact supermassive objects

Proceeded from the gravitation equations proposed by one of authors it was argued in a previous paper that there can exist supermassive compact configurations of degenerated Fermi‐gas without events horizon. In the present paper we consider the stability of these objects by a method like the one used in the theory of stellar structure. It is shown that the configurations are stable.     

Measurements of radio emission from the compact source in the Crab nebula with the uran-1 interferometer at 16.7, 20 and 25 MHz

This paper presents the results of measurements of the Crab nebula in the decametre range with an interferometer whose baseline is 2.4–3.5×10³ of the wavelength. Visibility function values, which in these observations determine the contribution by the compact source to the total nebula flux, have been measured at frequencies 16.7, 20 and 25 MHz to be 0.64±0.07, 0.43±0.04 and 0.31±0.03, respectively. The spectral index of the spectrum obtained for the compact source in the range 16.7–122 MHz is 2.09±0.04. Flattening of the nebula spectrum without the compact source has been confirmed for the decametre range.     

Supernovae in helium star–compact object binaries: a possible γ-ray burst mechanism

Helium star–compact object binaries, and helium star–neutron star binaries in particular, are widely believed to be the progenitors of the observed double-neutron-star systems. In these, the second neutron star is presumed to be the compact remnant of the helium star supernova. In this paper, the observational implications of such a supernova are discussed, and in particular are explored as a candidate γ-ray burst mechanism. In this scenario, the supernova results in a transient period of rapid accretion on to the compact object, extracting via magnetic torques its rotational energy at highly super-Eddington luminosities in the form of a narrowly beamed, strongly electromagnetically dominated jet. Compton scattering of supernova photons advected within the ejecta, and photons originating at shocks driven into the ejecta by the jet, will cool the jet and can produce the observed prompt emission characteristics, including the peak-inferred isotropic energy relation, X-ray flash characteristics, subpulse light curves, energy-dependent time lags and subpulse broadening, and late time spectral softening. The duration of the burst is limited by the rate of Compton cooling of the jet, eventually creating an optically thick, moderately relativistically expanding fireball that can produce the afterglow emission. If the black hole or neutron star stays bound to a compact remnant, late term light curve variability may be observed as in SN 2003dh.     

On fractional kinetic equations

The subject of this paper is to derive the solution of generalized fractional kinetic equations. The results are obtained in a compact form containing the Mittag-Leffler function, which naturally occurs whenever one is dealing with fractional integral equations. The results derived in this paper provide an extension of a result given by Haubold and Mathai in a recent paper (Haubold and Mathai, 2000). This revised version was published online in July 2006 with corrections to the Cover Date.     

Photometric catalogue of Shakhbazian compact groups of galaxies. II

The second part of the photometric catalogue of Shakhbazian compact groups of galaxies contains optical and geometrical properties of another 24 groups (Shkh 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287). As in the first paper photometric data were obtained from the COSMOS/UKST catalogue of the Southern sky with δ ≤ +2°30′. The survey of compact galaxy groups by Shakhbazian, Petrosian, Baier, and Tiersch is a basis for studying dynamical processes in such groups.     

Solar VLBI of compact transient sources

Very Long Baseline Interferometry offers the only technique for resolving the transient compact sources which, according to an increasing weight of observational and theoretical evidence, occur during solar flares. In this paper we discuss the problems of applying VLBI to observing the Sun, the results obtained so far and how the technique may be effectively employed in future studies of compact emission structures in solar flares.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.     

On the nature of quasars and active galactic nuclei

Attractive features and difficulties of the most widely held concepts on the energy sources in quasars and active galactic nuclei (a supermassive rotating magnetoplasmic body, an accreting black hole, a compact star cluster) are reviewed and discussed. In the light of the available data (particularly of recent results on the character of optical variability in a number of objects) models of a compact star cluster seem improbable. The concept of a magnetoid is less vulnerable, but the final choice between magnetoid and accreting black hole will be possible only after the details of these models have been thoroughly elaborated, and when new observational data become available.An extended version of the paper read at the Joint Meeting of Commissions 40 and 48 at the XVI General Assembly of the IAU (Grenoble, 27 August, 1976).     

Photometric catalogue of Shakhbazian compact groups of galaxies. III.

The third part of the photometric catalogue of Shakhbazian compact groups of galaxies contains optical and geometrical properties of another 24 groups (Shkh 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312). As in the first paper photometric data were obtained from the COSMOS/UKST catalogue of the Southern sky with δ ⩽ +2°30'. The survey of compact galaxy groups by Shakhbazian, Petrosian, Baier, and Tiersch is a basis for studying physical properties of such groups.     

Solution of Generalized Fractional Reaction-Diffusion Equations

This paper deals with the investigation of a closed form solution of a generalized fractional reaction-diffusion equation. The solution of the proposed problem is developed in a compact form in terms of the H-function by the application of direct and inverse Laplace and Fourier transforms. Fractional order moments and the asymptotic expansion of the solution are also obtained.     

上海天文台氢钟的研制现状及其应用前景

介绍了上海天文台氢钟的研制现状及其应用情况 ,展望了其潜在应用前景。对目前氢钟小型化国内外研究现状、我国进行小型氢钟的研制方案、拟解决的关键问题也进行了论述。同时给出了小型氢钟的预期性能指标     

Statistical study of the north–south asymmetry of the solar differential rotation based on various solar structures during 1966–1985

The time variation and latitude dependence of the solar rotation are found using observational data on Hα filaments and compact magnetic features with different polarities during solar activity cycles 20 and 21 (1966–1985). Statistical analysis of the observational data shows that there is a north–south asymmetry in the rotation, both for the Hα filaments and for compact magnetic features (structures) with negative and positive polarities. The N-S asymmetry in the differential rotation of the Hα filaments and the compact magnetic features with both polarities shows up quite distinctly in solar activity cycles 20 and 21, but the asymmetry for the compact magnetic features with positive polarity is comparatively lower in cycle 21. The confidence level is lower the compact magnetic features with positive polarity than for the compact magnetic features with negative polarity.     

Gravitational microlensing of gamma-ray bursts at medium optical depth

Gravitational lensing of a gamma-ray burst (GRB) by a single point mass will produce a second, delayed signal. Several authors have discussed using microlensed GRBs to probe a possible cosmological population of compact objects. We analyse a closely related phenomenon: the effect of microlensing by low to medium optical depth in compact objects on the averaged observed light curve of a sample of GRBs. We discuss the cumulative measured flux as a function of time resulting from delays caused by microlensing by cosmological compact objects. The time-scale and curvature of this function describe unique values for the compact object mass and optical depth. For GRBs with durations larger than the detector resolution, limits could be placed on the mass and optical depth of cosmological compact objects. The method does not rely on the separation of lensed bursts from those that are spatially coincident.