柴达木盆地北缘赛坝沟金矿床碲化物的发现及其来源探讨

赛坝沟金矿床位于柴北缘赛什腾山—阿尔茨托山成矿带东南段,含金石英脉主要赋存于早奥陶世英云闪长岩的断裂、节理裂隙内.流体成矿过程从早到晚划分为黄铁矿烟灰色石英脉阶段(Ⅰ)、黄铁矿白色石英脉阶段(Ⅱ)、多金属硫化物-灰白色-灰褐色石英脉阶段(Ⅲ)、灰白色石英-方解石脉阶段(Ⅳ).通过矿相学观察、能谱及电子探针分析,在该矿床Ⅱ、Ⅲ阶段矿石中首次发现大量的金/银/铅的碲化物,主要产出在黄铁矿、石英或其裂隙中,矿物生成顺序可初步厘定为黄铁矿→黄铜矿→自然金、碲铅矿→碲金矿→碲金银矿.基于赛坝沟金矿床矿石特征、成矿阶段及铅同位素特征,结合前人围岩及成矿年代学、成矿流体和同位素研究,初步认为矿床中金碲物质来源于早志留世深部地幔和下地壳混熔形成的岩浆流体,成矿流体沿大型剪切带上升,并与地表大气降水混合后在剪切带相对张性及韧脆性转换等构造薄弱部位富集成矿.     

Detection of the first thermonuclear X-ray burst from AX J1754.2-2754

When analyzing the archival data of the INTEGRAL observatory, we detected an intense X-ray burst recorded on April 16, 2005, by the JEM-X and IBIS/ISGRI telescopes from the weak and poorly studied source AX J1754.2-2754. Analysis of its time profiles and spectra allows this event to be attributed to type I X-ray bursts associated with thermonuclear explosions on the surfaces of neutron stars and the source itself to X-ray bursters. Peculiarities of the X-ray emission observed at the initial evolutionary phase of the burst point to a dramatic expansion and a corresponding cooling of the neutron star photosphere that took place at this time under the action of radiation pressure. Assuming the luminosity of the source at this phase to be the Eddington one, we have estimated the distance to the burst to be d = 6.6 ± 0.3 kpc (for a hydrogen atmosphere of the neutron star) and d = 9.2 ± 0.4 kpc (for a helium atmosphere).     

The first observation of AX J1749.1-2733 in a bright X-ray state—Another fast transient revealed by INTEGRAL

An intense outburst of hard radiation (with a peak flux of ～50 mCrab) was detected from the X-ray transient AX J1749.1-2733 by the IBIS/ISGRI gamma-ray telescope onboard the INTEGRAL observatory when the Galactic center field was monitored on September 8–10, 2003. Previously, this source had never been observed in a bright X-ray state. During the outburst, the source’s radiation spectrum was gently sloping and hard (extended to ～100 keV), followed a power law in the standard X-ray energy range, and had an exponential cutoff above 40–50 keV. The spectral hardness decreased with increasing flux. These and other properties described here and the shortness of the outburst (<2 days) allow the source to be attributed to the group of fast X-ray transients many representatives of which have an early O-B supergiant as their optical counterpart. Possible causes of the outbursts of fast transients are discussed. We show that accretion from the supergiant’s stellar wind should have led to intense persistent radiation from transients. The absence of radiation can be explained by the ejection of accreting matter from the system (propeller effect) during its contact with the magnetosphere of a rapidly rotating neutron star. Transient outbursts could originate in sources of this type if the spin period of their neutron star P _s differed only slightly from the critical period P _s ^* ? 3 s at which the propeller effect is still possible. The outburst is triggered by an insignificant rise in the local stellar wind density, by a factor of (P _s ^* /P _s)^7/3. The entire outburst profile cannot be explained by an individual inhomogeneity in the wind, but is the reflection of a long-term (～2 days for AX J1749.1-2733) change in the rate of wind outflow from the supergiant’s surface facing the compact source. The rate of wind outflow could be enhanced through X-ray heating of the supergiant’s surface.     

Cosmic GRB 060428C detected in the field of view of the IBIS and SPI telescopes onboard the INTEGRAL observatory and its early afterglow

While analyzing the archival data of the INTEGRAL observatory, we detected and localized a cosmic gamma-ray burst recorded on April 28, 2006, by the IBIS/ISGRI and SPI telescopes in their fields of view. Since the burst was not revealed by the INTEGRAL burst alert system (IBAS), information about its coordinates was not distributed in time and no search for its afterglow was conducted. The burst was recorded by the KONUS/WIND and RHES SI satellites. Its 20–200-keV fluence was 2.3 × 10^?6 erg cm^?2, the peak flux was 3.6 × 10^?7 erg cm^?2 s^?1 (3.9 phot. cm^?2 s^?1). The burst had a complex multipeaked profile and stood out among typical bursts by an increase in its hardness with time. At the flux peak, the spectrum was characterized by a photon index α ? ?1.5 and a peak energy E _p ? 95 keV. The burst lasted for ～12 s, after which its afterglow decaying as a power law with an index γ ～ ?4.5 was observed at energies 15–45 keV. The spectral hardness decreased noticeably during the afterglow.     

氢氧稳定同位素技术在生态系统水分耗散中的应用研究进展

氢氧稳定同位素作为水的"DNA",对于研究水分的传输和转化具有重要的意义,而水分耗散是水循环的重要组成部分。简单介绍氢氧稳定同位素在水分耗散研究中应用的主要原理和比较新的一些技术方法,主要对其在森林、草原生态系统和农田生态系统中蒸散发分离,植物水分来源区分、叶片水同位素富集和水分利用效率等方面做较为详细的归纳总结和探讨,最后指出国内此类研究仍然存在的问题和可能的发展方向,以期对未来氢氧稳定同位素技术在水分循环和水分耗散方面的应用研究有借鉴作用。     

Normal galaxies in the all-sky survey by the eROSITA X-ray telescope of the Spectrum-X-Gamma observatory

We analyze the statistical properties of normal galaxies to be detected in the all-sky survey by the eROSITA X-ray telescope of the Spectrum-X-Gamma observatory. With the current configuration and parameters of the eROSITA telescope, the sensitivity of a 4-year-long all-sky survey will be ≈10^?14 erg s^?1 in the 0.5–2 keV band. This will allow ～(1.5–2) × 10⁴ normal galaxies with approximately the same contribution of star-forming and elliptical galaxies to be detected. All galaxies of the X-ray survey are expected to enter into the existing far-infrared (IRAS) or near-infrared (2MASS) catalogs; the sample of star-forming galaxies will be approximately equivalent in sensitivity to the sample of star-forming galaxies in the IRAS catalog of infrared sources. Thus, a large homogeneous sample of normal galaxies with measured X-ray, near-infrared, and far-infrared fluxes will be formed. About 90% of the galaxies in the survey are located within ～200–400 Mpc. A typical (most probable) galaxy will have a luminosity log L _X ～ 40.5–41.0, will be located at a distance of ～70–90 Mpc, and will be either a star-forming galaxy with a star formation rate of ～20M _⊙ yr^?1 whose X-ray emission is produced by ultraluminous X-ray sources (ULXs) or an elliptical galaxy with amass log M _* ～ 11.3 emitting through to a hot interstellar gas. The galaxies within 35 Mpc will collectively contain ～10² ULXs with luminosities log L _X > 40, ～80% of whichwill be the only luminous source in the galaxy. Thus, although the angular resolution of the eROSITA telescope is too low for the luminosity function of compact sources in galaxies to be studied in detail, the survey data will allow one to investigate its bright end and, possibly, to impose constraints on the maximum luminosity of ULXs.     

Highlights of fifty years of atmospheric aerosol research at Mace Head

This paper summarises the development and principal results of fifty years of research on aerosols in the marine atmosphere at Mace Head Atmospheric Research Station on the west coast of Ireland. It concentrates on the sources, physico-chemical properties, number and mass concentrations, size range, volatility and chemical composition of aerosols in different air masses. It also examines optical properties of the aerosols and their long-range transport.     

The enhanced spectrum of the symbiotic variable star CH Cygni on November 2, 2006

The symbiotic variable star CH Cygni went on the deepest minimum phase in December 2006. A high-resolution spectrum of CH Cygni obtained at the Bohyunsan Optical Astronomy Observatory (BOAO) on November 2, 2006, is reported. The spectrum of CH Cygni obtained at the BOAO was calibrated on a scale of an absolute-flux density. Emission lines of H I, [O III], [N II], and [S II] were strong, with several components, and Ca II, H, and K lines had P-Cygni profiles. Removal of the spectrum of the underlying M-type star from the CH Cygni spectrum was completed to obtain the true emission profiles. The radial velocities of all emission and absorption lines were measured. Some of the observed lines were also deconvoluted using multi-Gaussian functions to find the relationship between line shapes and the corresponding sources of these lines. The results obtained are discussed in terms of an accretion disk around the hot star, and in non-spherically extended nebular regions.     

冷热源系统监控设计

总结了楼宇自控系统在不同冷热源中的应用,并结合原理图作出比较分析。