东北亚区域可持续发展的主要科学问题探讨

东北亚各国自然地域相连,社会经济联系密切,形成了东北亚独特的经济地域系统。在全球变化背景下,深入探讨东北亚区域可持续发展面临的主要科学问题具有重要的理论与实践意义。东北亚区域生态经济巨系统的结构、功能和地域分异规律及其动态演变格局是该区域可持续发展的基本科学问题;驱动力因子是该区域可持续发展研究的重要问题;跨境区域社会经济可持续发展模式是该区域可持续发展的核心问题和归宿,而东北亚区域可持续发展支撑平台建设是重要的技术支撑和保障。东北亚、中亚地区作为一个资源、环境、经济和社会复杂巨系统,其可持续发展还有许多重要科学问题,需要该区域科学家联合攻关,共同探索。     

Analysis of spatial temperature variations in regions of massive star formation

Using the 20-m Onsala Observatory telescope (Sweden), we performed observations of the CH₃C₂H(6-5) line toward several regions of massive star formation to estimate the kinetic temperature of the gas and study its variations over the sources. Intense lines were detected in five objects. For these, we estimated the kinetic temperature of the gas near the CS and N₂H⁺ molecular emission peaks by the method of population diagrams. A significant temperature difference between these peaks is noticeable only in W3 and, to a lesser degree, in DR 21. In the remaining cases, it is insignificant. This indicates that the chemical differentiation of the molecules in these regions cannot be associated with temperature variations. The kinetic temperature determined from methyl acetylene observations is usually slightly higher than the temperature estimated from ammonia observations. This is probably because the methyl acetylene emission originates in denser, i.e., deeper and hotter layers of the cloud.     

Experimental simulation of the formation of non-circular active depressions on Comet Wild-2 and of ice grain ejection from cometary surfaces

Following the tracing of jets emanating from Comet Wild-2 to depressions in the ice by Brownlee et al. [2004. The Stardust—A successful encounter with the remarkable Comet Wild 2. Lunar Planet. Sci. 35. Abstract 1981], we demonstrated experimentally the formation of depressions and chaotic terrain on comet analogs when gas is released from underlying ice pockets. We also demonstrated experimentally the ejection of ice grains into the experimental cometary “coma.”     

The source of energy of the comet 29P/Schwassmann-Wachmann 1 outburst activity: the test of the summary

The comet 29P/Schwassmann-Wachmann 1 is an exceptional comet as far as cometary outbursts are concerned. Despite its large distance from the Sun (about 6 au), it shows quasi-regular outburst activity, usually once or twice a year. Up to now there has not been a generally accepted model that explains this phenomenon. In the first part of this paper, the most well-known hypotheses that attempt to explain the outburst activity of this comet are presented and critically analysed. The main aim of this paper is to present a model for the outburst activity of this comet. The model is based on the global analysis of the internal structure and physical and chemical processes that take place in the cometary nucleus. Numerical calculations were carried out for reasonable assumed values of a large range of cometary characteristics. The obtained results are consistent with observational data.     

Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2003

Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the north poles of rotation and the prime meridians of the planets, satellites, and asteroids. This report introduces a system of cartographic coordinates for asteroids and comets. A topographic reference surface for Mars is recommended. Tables for the rotational elements of the planets and satellites and size and shape of the planets and satellites are not included, since there were no changes to the values. They are available in the previous report (Celest. Mech. Dyn. Astron., 82, 83–110, 2002), a version of which is also available on a web site.     

Estimating the Size of Hale-Bopp's Nucleus

A variety of independent methods have been used to estimate the size of the nucleus of comet Hale-Bopp. Several groups have analyzed optical and infrared images of the comet and claim to detect the signature of the nucleus, despite the presence of a strong coma. A detection of the nucleus was also claimed during mm- and cm-wave observations of Hale-Bopp shortly before perihelion. A team of observers detected the occultation of a star by the nucleus of Hale-Bopp in October 1996. The maximum observed gas production rate of the comet near perihelion can be used to place a lower limit on the size of the nucleus. This paper critically reviews the many different methods used to constrain the size of Hale-Bopp's nucleus. All of the techniques are affected by systematic errors that can be difficult to quantify precisely. Nevertheless, the available evidence strongly suggests that the nucleus of Hale-Bopp has an effective radius of at least 15 km and is probably in the range 20–35 km. Thus, the prodigious gas and production rates from this comet are naturally explained by its unusually large size. This revised version was published online in July 2006 with corrections to the Cover Date.