五大连池火山群新期火山渣丘成因的探讨

火山渣丘,是火山区内的一种特殊的地质现象,以前地其成因国内外尚无详细探讨和描述,有的学者曾经统称为副火山。笔者通过实地调查,对这一结论提出新的见解,认为火山渣丘的形成是一复杂的地质现象,其成因具有多元性。这对探讨火山喷发规律,对火山地质地貌的准确描述与具有积极作用。     

四川木里耳泽岩溶型金矿床形成条件和成矿机制

四川本里耳泽金-菱铁矿建造矿床,赋存于上二叠统海相碳酸盐岩层中,矿化受古岩溶的严格控制,组成矿石的基本矿物为菱铁矿,金不均匀地分布于菱铁矿矿体内。成矿溶液来自加热的循环地下水。成矿过程分为早阶段和中-晚阶段。成矿温度为156-210℃,成矿深度小于1km.成矿物质主要来自地层。成矿热液呈碱性和弱还原性,贫硫,含中等盐度。矿床形成时的地质构造环境较稳定。这是我国仅见的一种特殊金矿类型。     

The effect of an optically thin region on stability of an accretion disk around a supermassive black hole

We analyse conditions of the innermost portion of an accretion disk and establish a set of equations for this region. A stable innermost region may exist, which can probably explain the observed UV and X-ray spectra, avoiding the unstable emission. We then discuss the detailed radial structure of a disk around a black hole for typical AGN parameters and obtain different kinds of- relationships for different regions of a disk. On the basis of this, we discuss the stability. A new type of cycle is present, which we call a double S shaped cycle. In this cycle, the extent of accretion rate variability is much larger than that in dwarf nova cycles. This probably solves the problem of violent variability of AGN. In the meantime, the very high accretion rate at the hottest state in limit cycles in the unstable region may provide continuous injection of matter to the jet and power the relativistic motion of the jet.     

On the internal structure and magnetic fields of

First, a sequence of four-zone models for the interior of Venus is constructed under the assumption of hydrostatic equilibrium. While the equation of state for each zone is taken to be the Bullen's relation with its coefficients consistent with the PREM Earth model (Dziewonski and Anderson, 1981), the position of core-mantle boundary is determined by matching solutions of the Emden's equation in different regions. The results of hydrostatic models indicate the presence of a reasonably large molten iron core in Venus, broadly similar to the Earth. It is also found that the position of the core-mantle interface is nearly model-independent. Second, we focus on the question why Venus does not possess a significant global magnetic field and on what we can learn from this fact. Solutions of magnetohydrodynamic equations appropriate for the molten core of Venus are discussed. It is argued that, because the Elsasser number measuring the relative importance of Coriolis and Lorentz forces satisfies 1, equations for the problem of thermal convection in the Venusian fluid core must be nearly uncoupled with the dynamo equation. The existence of a global magnetic field, though small, then suggests that the size of the magnetic Reynolds numberR _m must beR _m =O(10), sustaining a dynamo action near its marginal state but not an active dynamo in the Venusian molten core. On the basis of asymptotic relations for finite amplitude convection, a useful constraint on important physical parameters for the liquid core of Venus is derived and discussed.     

Kleť minor planet discovery frequency by months (comparison)

Abstrakt The Kle search programme for minor planets using 0,63m Maksutov camera of Kle Observatory was begun in 1977 as a long-term project continuing up to the present day. The discovery frequency according to seasons in the year shows multiple differences between particular months.The comparison with the number of observing nights and obtained search plates; weather conditions and other influences will be discussed. The Kle minor planet discovery frequency also will be compared with the data base of all numbered minor planets.     

On matching the spectrum of Io: Variations in the photometric properties of sulfur-containing mixtures

The problem of comparing laboratory spectra of sulfur-containing binary mixtures with the spectrum of Io is discussed. For the satellite, the observable is the geometric albedo as a function of wavelength, whereas in the laboratory one often measures some other type of albedo. In a previous paper we demonstrated that for pure sulfur the multiplicative factor which converts the laboratory albedos to geometric albedos can be strongly wavelength dependent. The present paper demonstrates that this is also true for binary sulfur-containing mixtures. Furthermore, there is no universal conversion factor applicable to all binary mixtures, nor can the factor be interpolated for a particular mixture from the conversion factors of the two end members. The conversion factor is a function not only of the specific composition of a binary mixture, but of the relative particle size distributions of the two components, and must be measured specifically for each individual sample if a quantitative comparison between a laboratory sample and Io's surface is desired.     

On transfer equation in a semi-infinite atmosphere with albedo ω>1

In this note we derive an exact solution of transfer equation in a plane-parallel semiinfinite atmosphere with albedo >1, by the method of Laplace transform and Wiener-Hopf technique. The emergent intensityI(0, ) is obtained in terms of theH ⁰-functionH ⁰() (Das Gupta, 1978) for which some good approximations are given. Intensity at any depth is also obtained.I(0, )/I(0, 0) is plotted in graphs against [0,1], and shows a maximum which drops and shifts towards the origin as increases.     

Observations and interpretation of the close binary system CG Cyg

Photometric observations of the short-period (RS CVn-type) eclipsing binary system CG Cyg have been presented. Two sets of results, obtained from an analysis of theB, V andR light curves, represent ‘occultation’ and ‘transit’ solutions. The occultation solution is preferred as it gives a better fit to the colour curve. This hypothesis may also offer a more promising explanation of the observed peculiarities such as period changes and the light variation outside eclipses.     

Transequatorial loops interconnecting McMath regions 12472 and 12474

We discuss the life-story of a transequatorial loop system which interconnected the newly born active region McMath 12474 with the old region 12472. The loop system was probably born through reconnection accomplished 1.5 to 5 days after the birth of 12474 and the loops were observed in soft X-rays for at least 1.5 days. Transient sharpenings of the interconnection and a striking brightening of the whole loop system for about 6 hr appear to be caused by magnetic field variations in the region 12474. A flare might have been related to the brightening, but only in an indirect way: the same emerging flux could have triggered the flare and at the same time strengthened the magnetic field at the foot-points of the loops. Electron temperature in the loop system, equal to 2.1 × 10⁶ K in its quiet phase, increased to 3.1 × 10⁶ K during the brightening. Electron density in the loop system was 1.3 × 10⁹ cm^–3 and it could be estimated to 7 × 10⁸ cm^–3 prior to the brightening. During the brightening the loops became twisted. There was no obvious effect whatsoever of the activity in 12474 upon the in erconnected old region. The final decay of the loop system reflected the decay of magnetic field in the region 12474.     

Unusual coronal activity following the flare of 6 November 1980

For almost 30 hr after the major (gamma-ray) two-ribbon flare on 6 November 1980, 03:30 UT, the Hard X-Ray Imaging Spectrometer (HXIS) aboard the SMM satellite imaged in > 3.5 keV X-rays a gigantic arch extending above the active region over the limb. Like a similar configuration on 22 May 1980, this arch formed the lowest part of a stationary post-flare radio noise storm recorded at metric wavelengths at Nançay and Culgoora. 6.5 hr after the flare a coronal region below the arch started quasi-periodic pulsations in X-ray brightness, observed by several SMM instruments. These brightness variations had no response in the chromosphere (H), very little in the transition layer (O v), but they clearly correlated with similar variations in brightness at 169 MHz. There were 13 pulses of this kind, with apparent periodicity of about 20 min, until another flare occurred in the active region at 15:00 UT. All the brightenings appeared within a localized area of about 30000 km² in the northern part of the active region, but they definitely did not occur all at the same place.The top of the X-ray arch, at an altitude of 155 000 km, was continuously and smoothly decaying, taking no part in the striking variations below it. Therefore, the area variable in brightness does not seem to be the footpoint of the arch, as we supposed for similar variations on 22 May. More likely, it is a separate region connected directly with the source of the radio storm; particles accelerated in the storm may be dumped into the low corona and cause the X-ray enhancements. The X-ray arch was enhanced by two orders of magnitude in 3.5–5.5 keV X-ray counts and the temperature increased from 7.3 × 10⁶ to 9 × 10⁶ K when the new two-ribbon flare occurred at 15:00 UT. Thus, it is possible that energy is brought into the arch via the upper parts of the reconnecting flare loops - a process that can continue for hours.