矩尺天区的近红外天体

利用Ｒ（红）－Ｉ（近红外）两色照相测光方法，搜寻银道带天区的红外超天体，并证认ＩＲＡＳ点源的红外超对应体。本文是一组系列文章的第四篇。在矩尺天区发现了１９５个红外超天体，并证认出其中２２个是ＩＲＡＳ点源的对应体。     

BLLac天体的谱性质

研究了等离子体反应堆模型,统一解释活动星系核的辐射性质,特别是ＢＬＬａｃ天体的谱性质,具体的物理过程是：大量相对论电子从中心天体注入周转的等离子体反应堆中,通过同步辐射快速损失能量,同时这些电子同步吸收反应堆中遥光子,产生一个稳定,各向同性的幂律分布,其谱指数为γ＝３;然后,这些相对论电子通过等离子反应堆的爆发发或其表面扩散过程逃逸出来,产生低频的同小辐射;来自等离子体反应堆的高频辐射表现出快速的     

矩尺天区的近红外天体

利用Ｒ（红）－Ⅰ（近红外）两色照相测光方法，搜寻银道整天区的红外超天体，并证认ＩＲＡＳ点源的红外超对应体。本是一组系列章的第四篇。在矩尺天区发现了１９５个红外超天体，并证认出其中２２个是ＩＲＡＳ点源的对应体。     

X选BL Lac天体的某些性质

本文给出了包含５６个Ｘ选择的ＢＬ Ｌａｃ天体（ＸＢＬｓ）的完备样品，得到了一些相互关系并讨论了ＸＢＬｓ的一些性质。     

天坛天区的近红外天体

本课题的研究目的是利用R(红)-l(近红外)两色照相测光方法,搜寻银道带天区的红外超天体,并证认IRAS点源的近红外光学对应体。本文是一组文章的第二篇。在天坛天区发现了225个红外超天体,并证认出其中27个为IRAS点源的对应体。     

船底天区的近红外天体

本课题的研究目的是利用R(红)—I(近红外)两色照相测光方法,搜寻银道带天区的红外超天体,并证认IRAS点源(文[1])的近红外光学对应体,本文是一组文章的第三篇,在船底天区发现了89个红外超天体,并证认出其中12个是IRAS点源的对应体。     

船帆天区的近红外天体

本课题的研究目的是利用R(红)—I(近红外)两色照相测光方法,搜寻银道带天区的红外超天体,并证认IRAS点源的近红外光学对应体。     

BL Lac天体的谱性质

研究了等离子体反应堆模型,统一解释活动星系核的辐射性质,特别是ＢＬＬａｃ天体的谱性质．具体的物理过程是:大量相对论电子从中心天体注入周围的等离子体反应堆中,通过同步辐射快速损失能量,同时这些电子同步吸收反应堆中不透明的光子,产生一个稳定、各向同性的幂律分布,其谱指数为γ＝３;然后,这些相对论电子通过等离子体反应堆的爆发或其表面扩散过程逃逸出来,产生低频的同步辐射;来自等离子体反应堆的高频辐射表现出快速的谱变化,即流量减小时谱变陡．另外,还详细分析了具有辐射损失和相对论电子注入的同步辐射源的性质．     

The properties of the dust shell of BN Object

In this paper we make a theoretical analysis of multi-wavelength photometric data on the infrared continuum of BN Object. Adopting a spherically symmetric, optically thin shell model we derive its optical thickness, its infrared emissivity as a function of wavelength, its radial distributions of density and temperature and its total mass.     

危险目标再入跟踪预报研究

本文讨论了危险目标再入的有关问题,通过２２８７０和２５１００两个卫星陨落期预报的实践,我们形成了一种计算卫星落点的方法,方法的基本要点是：１算准卫星的面质比;２在１８０公里以下,考虑阻尼系数随高度（大气密度）的变化;３在计算落点时,使用两组根数,调整面质比使两组根数计算的落点基本相同,并验证面质比调整的合理性;４对于ＭＳＩＳ－１９９０模式,我们发现调整后的面质比要比理论的面质比大１．０９倍,也许这     

PHYSICAL PROPERTIES OF METEORITES AND INTERPLANETARY DUST PARTICLES: CLUES TO THE PROPERTIES OF THE METEORS AND THEIR PARENT BODIES

Meteorites, generally 1 cm or larger in size that are believed to sample asteroids, and interplanetary dust particles (IDPs), generally 5–50 μm in size that are believed to sample both asteroids and comets, span the size range of the meteors. Thus, the physical properties of the meteorites and the IDPs are likely to constrain the properties of the meteors and their parent bodies. Measurements of the density, porosity, longitudinal and transverse speeds of sound, elastic modulus, and bulk modulus, as well as imaging of the internal structure by Computed Microtomography indicate that unweathered samples of chondritic meteorites are more porous and have lower sound velocities than compact terrestrial rocks. In general, the IDPs are even more porous than the chondritic meteorites. The impact energy per unit target mass required to produce a barely catastrophic disruption (Q ^* _D) for anhydrous ordinary chondrite meteorites is twice that for terrestrial basalt or glass, indicating that collisional disruption of anhydrous meteorites requires more energy than for a compact basalt. These results indicate that most stone meteors are likely to be weak, porous objects, and that the parent bodies of the anhydrous stone meteorites are likely to be more difficult to disrupt than compact terrestrial basalt.     

The dust trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006

We report on observations of the dust trail of Comet 67P/Churyumov-Gerasimenko (CG) in visible light with the Wide Field Imager at the ESO/MPG 2.2 m telescope at 4.7 AU before aphelion, and at with the MIPS instrument on board the Spitzer Space Telescope at 5.7 AU both before and after aphelion. The comet did not appear to be active during our observations. Our images probe large dust grains emitted from the comet that have a radiation pressure parameter β<0.01. We compare our observations with simulated images generated with a dynamical model of the cometary dust environment and constrain the emission speeds, size distribution, production rate and geometric albedo of the dust. We achieve the best fit to our data with a differential size distribution exponent of −4.1, and emission speeds for a β=0.01 particle of 25 m/s at perihelion and 2 m/s at 3 AU. The dust production rate in our model is on the order of 1000 kg/s at perihelion and 1 kg/s at 3 AU, and we require a dust geometric albedo between 0.022 and 0.044. The production rates of large (>) particles required to reproduce the brightness of the trail are sufficient to also account for the coma brightness observed while the comet was inside 3 AU, and we infer that the cross-section in the coma of CG may be dominated by grains of the order of .     

基于GPS接收机的程控目标跟踪方法的气球飞行试验

简要介绍了基于ＧＰＳ接收机的程控目标跟踪方法原理和１９９８ 年５ 月的一次气球飞行试验结果．成功的飞行试验证明该方法对于用准直器限制视场的Ｘ 射线和＄射线气球天文观测非常适用,可提高观测灵敏度和简化数据处理过程,特别是在长距离飞行时可做到多目标自动对准和跟踪的自主闭环系统     

A tale of two very different comets: ISO and MSX measurements of dust emission from 126P/IRAS (1996) and 2P/Encke (1997)

We present the characteristics of the dust comae of two comets, 126P/IRAS, a member of the Halley family (a near-isotropic comet), and 2P/Encke, an ecliptic comet. We have primarily used mid- and far-infrared data obtained by the ISOPHOT instrument aboard the Infrared Space Observatory (ISO) in 1996 and 1997, and mid-infrared data obtained by the SPIRIT III instrument aboard the Midcourse Space Experiment (MSX) in 1996. We find that the dust grains emitted by the two comets have markedly different thermal and physical properties. P/IRAS's dust grain size distribution appears to be similar to that of fellow family member 1P/Halley, with grains smaller than 5 microns dominating by surface area, whereas P/Encke emits a much higher fraction of big (20 μm and higher) grains, with the grain mass distribution being similar to that which is inferred for the interplanetary dust population. P/Encke's dearth of micron-scale grains accounts for its visible-wavelength classification as a “gassy” comet. These conclusions are based on analyses of both imaging and spectrophotometry of the two comets; this combination provides a powerful way to constrain cometary dust properties. Specifically, P/IRAS was observed preperihelion while 1.71 AU from the Sun, and seen to have a 15-arcmin long mid-infrared dust tail pointing in the antisolar direction. No sunward spike was seen despite the vantage point being nearly in the comet's orbital plane. The tail's total mass at the time was about 8×10⁹ kg. The spectral energy distribution (SED) is best fit by a modified greybody with temperature T=265±15 K and emissivity ε proportional to a steep power law in wavelength λ: ε∝λ^−α, where α=0.50±0.20(2σ). This temperature is elevated with respect to the expected equilibrium temperature for this heliocentric distance. The dust mass loss rate was between 150-600 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 3.3, and the albedo of the dust was 0.15±0.03. Carbonaceous material is depleted in the comet's dust by a factor of 2-3, paralleling the C₂ depletion in P/IRAS's gas coma. P/Encke, on the other hand, observed while 1.17 AU from the Sun, had an SED that is best fit by a Planck function with T=270±15 K and no emissivity falloff. The dust mass loss rate was 70-280 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 2.3, and the albedo of the dust was about 0.06±0.02. These conclusions are consistent with the strongly curved dust tail and bright dust trail seen by Reach et al. (2000; Icarus 148, 80) in their ISO 12-μm imaging of P/Encke. The observed differences in the P/IRAS and P/Encke dust are most likely due to the less evolved and insolated state of the P/IRAS nuclear surface. If the dust emission behavior of P/Encke is typical of other ecliptic comets, then comets are the major supplier of the interplanetary dust cloud.     

γ射线噪Blazar天体中尘埃的作用

利用具有多波段谱指数及流量观测资料的５９ 个Ｂｌａｚａｒ 天体作为样本,我们研究了各波段流量之间,谱指数之间的可能的相关性。新的可能的限制已从理论上进行了深入地讨论。结果暗示：（１） 同步自康普顿机制是Ｂｌａｚａｒ 天体γ射线辐射的主要机制。（２） 相对论电子与吸收积盘热光子的逆康普顿散射是Ｂｌａｚａｒ 天体γ射线产生的另一个重要机制。（３）ＢＬＬａｃ 天体不是“纯非热辐射”的天体,它们也具有强的热辐射。     

低对比度扩展目标跟踪算法

针对如太阳表面米粒结构和太阳黑子这类低对比度扩展目标，研究了互相关因子和绝对差分两种跟踪算法的有效性，并给出了根据所采集的图像进行后处理所得到的小整体倾斜信号，此外还比较了去除整体倾斜前后的太阳表面米粒结构长曝光像的对比度。     

类星体的中红外光谱分析(英文)

分析了42个类星体的SPITZER IRS中红外光谱,并测量了连续谱和各发射特征强度,其中包括5.5μm连续谱强度、10μm silicate发射,和窄发射线[S IV]10.5μm,[Ne V]14.3μm,[NeIII]15.6μm,和[O IV]25.9μm的流量。5.5μm连续谱强度和窄发射线强度之间存在很强的相关关系,说明5.5μm连续谱也由活动星系核中心光子直接激发,并可以作为活动星系核强度的示踪。发现10μm silicate发射与Eigenvector I没有相关关系,说明类星体中大多数的尘埃不可能与窄线区共存。     

Evolution of the dusty rings of Uranus

We present high quality images of the uranian ring system, obtained in August 2002, October 2003, and July 2004 at 2.2 μm with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first detection in backscattered light of a ring (which we refer to as the ζ ring) interior to Uranus' known rings. This ring consists of a generally uniform sheet of dust between 37,850 and 41,350 km with an equivalent width (in 2004; or ), and extends inward to 32,600 km at a gradually decreasing brightness. This ring might be related to the Voyager ring R/1986 U 2, although both its location and extent differ. This could be attributed to a difference in observing wavelength and/or solar phase angle, or perhaps to temporal variations in the ring. Through careful modeling of the I/F of the individual rings at each ansa, we reveal the presence of narrow (few 100 km wide) sheets of dust between the δ and ε rings, and between rings 4 and α. We derived a typical anisotropy factor g≈0.7 in the scattering behavior of these particles. The spatial distribution and relative intensity of these dust sheets is different than that seen in Voyager images taken in forward scattered light, due either to a difference in observing wavelength, and/or solar phase angle or to changes over time. We may have detected the λ ring in one scan at , but other scans provided upper limits below this value. A single detection, however, would be consistent with azimuthal asymmetries known to exist in this ring. We further demonstrate the presence of azimuthal asymmetries in all rings. We confirm the eccentricity of ∼0.001 in rings 4, 5, 6, which in 2004 are ∼70 km closer to Uranus in the north (near periapse; lower I/F) than in the south. We find a global optical depth of τ∼0.3 in the main rings, and of τ=0.25±0.05 in the ε ring.