Observations of Comet C/2001 A2 (Linear) with the Multipupil Fiber Spectrograph

We present preliminary results of observations of the spectrum of comet C/2001 A2(LINEAR) obtained with the Multipupil Fiber Spectrograph, installed in the PrimeFocus of the 6-m Telescope of the SAO of the RAS (Northern Caucasus, NizhnyArkhyz), on August 11/12, 12/13 and 14/15, 2001. High resolution spectra of thecomet were obtained in the range from 3800–5200 AA. The emission lines in the spectrum of comet C/2001 A2 (LINEAR) on Aug. 12, 2001 were identified. Thefluorescent continuum in the spectrum of comet C/2001 A2 (LINEAR) on Aug. 12,2001 is detected.     

Astronomy with a mid-infrared echelle spectrograph

Irshell, a mid-infrared echelle spectrograph developed through a collaboration between the University of Texas, the University of California Space Sciences Laboratory, and Hughes Aircraft, has been in regular use for astronomical observations for about five years. It is optimized for high spectral resolution (R10,000) observations of narrow spectral regions (/1/300) and compact sources (a few arcsec), and is sensitive in the 5–25 m region. A wide variety of astronomical objects have been studied. Observing techniques have been developed to achieve maximum sensitivity in those observations for which Irshell is best suited and to allow observations of wide spectral regions and extended objects. We discuss the observing techniques and show some of the data obtained.     

A Preliminary Study of the Types of Volcanic Earthquakes and Volcanic Activity at the Changbaishan Tianchi Volcano

INTRODUCTIONThe Changbaishan volcano is located in Jilin Province , along the border of China and NorthKorea .It isthelargest nature reservein China .Changbaishan belongstothe northeastern Asian activebelt in the eastern margin of the Euro-Asia plate . The Changbaishan volcano is a gigantic ,polygenetic ,central volcano,and has been active since Holocene .The early eruption started in thePliocene andformedthe basaltic shield. Duringthe middle and late Pleistocene ,the volcanic cone …     

Daytime Turbulence Statistics above a Steep Forested Slope

Six levels of simultaneously sampled ultrasonic data are used to analyse the turbulence structure within a mixed forest of 13 m height on a steep slope (35°) in an alpine valley. The data set is compared to other studies carried out over forests in more ideal, flat terrain. The analysis is carried out for 30-min mean data, joint probability distributions, length scales and spectral characteristics.Thermally induced upslope winds and cold air drainage lead to a wind speed maximum within the trunk space. Slope winds are superimposed on valley winds and the valley-wind component becomes stronger with increasing height. Slope and valley winds are thus interacting on different spatial and time scales leading to a quite complex pattern in momentum transport that differs significantly from surface-layer characteristics. Directional shear causes lateral momentum transports that are in the same order or even larger than the longitudinal ones. In the canopy, however, a sharp attenuation of turbulence is observed. Skewed distributions of velocity components indicate that intermittent turbulent transport plays an important role in the energy distribution.Even though large-scale pressure fields lead to characteristic features in the turbulent structure that are superimposed on the canopy flow, it is found that many statistical properties typical of both mixing layers and canopy flow are observed in the data set.     

Feinauflösung von UV-Spektren durch Differentiation 1. und 2. Ordnung im Rahmen der Kohlenwasserstoffanalyse

Fine Resolution of UV Spectra by Differentiation of 1st and 2nd Order in Hydrocarbon Analysis Basic UV spectra (0th order) in unpolar solvents such as cyclohexane are useful — though with some reservations — in characterizing mineral oils occuring in pure form and aromatic fractions in environmental samples separated by chromatographic techniques. The common standard raffinates, biogenic hydrocarbons or other mixes of hydrocarbons including polycyclic aromatics can be approximately identified. The spectra of 1st and 2nd order improve the reliability of the results and permit above all to detect polycondensated aromatics even in traces. Finally, partial spectra of 1st and 2nd order in the wavelength ranges 205…240, 220…260, and 260…320 nm allow because of their very specific structures a simple and fast practically definite assignment to the above-mentioned groups of aromatics. Analogously, substituted aromatics in detergents and other technical products have already been identified. The method is suitable as a fast preliminary test, at least.     

层状地壳模型地面地下记录地震波的理论地震图和频谱计算

本文首先发展了计算层状介质地面及地下记录地震波理论地震图的部分分离变量—有限差分计算方法,其最主要的环节是引进了吸收边界条件,使计算工作量大大减少,得以在实际工作中推广应用。其次,应用矩阵方法计算地面及地下记录的地震波的理论频谱。最后给出了用上述方法得到的华北地区两种不同的理论地壳模型情况下的理论地震图和频谱计算结果。应用这些理论结果,可根据实际地震观测资料对地壳介质模型进行分析、评判和优选。     

Spectra of accretion discs around white dwarfs

We present the spectra of accretion discs around white dwarfs calculated with an improved and updated version of Shaviv and Wehrse [Shaviv, G., Wehrse, R., 1991. A&A 251, 117] model. The new version includes line opacities and convective energy transport and can be used to calculate the spectra of hot discs in bright systems (nova-like variables or dwarf novae in outburst) as well as the spectra of cold accretion discs in quiescent dwarf novae.     

Atmospheric Turbulence Characteristics Over a Temperature-Inhomogeneous Land Surface. Part I: Statistical Characteristics of Small-Scale Spatial Inhomogeneities of Land Surface Temperature

The results of our 1993 and 1994 experiments at the Tsimlyansk experimental site are given. Spatial variations of small-scale (0.1 m < l < 100 m) temperature inhomogeneities of a steppe surface have been measured. Considerable variations in surface radiation temperature T_r, with variances up to 5 K², have been found. The spectra of T_r variations are of a one-mode character. The position of the spectral maximum on the wavenumber scale depends on the surface characteristics and may change from year-to-year. Probability density distributions for steppe surface radiation temperature variations are close to a normal distribution.     

Aspects Of The Atmospheric Surface Layers On Mars And Earth

The structures of mean flow and turbulence in the atmospheric surface boundary layer have been extensively studied on Earth, and to a far less extent on Mars, where only the Viking missions and the Pathfinder mission have delivered in-situ data. Largely the behaviour of surface-layer turbulence and mean flow on Mars is found to obey the same scaling laws as on Earth. The largest micrometeorological differences between the two atmospheres are associated with the low air density of the Martian atmosphere. Together with the virtual absence of water vapour, it reduces the importance of the atmospheric heat flux in the surface energy budget. This increases the temperature variation of the surface forcing the near-surface temperature gradient and thereby the diabatic heat flux to higher values than are typical on the Earth, resulting in turn in a deeper daytime boundary layer. As wind speed is much like that of the Earth, this larger diabatic heat flux is carried mostly by larger maximal values of T_*, the surface scale temperature. The higher kinematic viscosity yields a Kolmogorov scale of the order of ten times larger than on Earth, influencing the transition between rough and smooth flow for the same surface features.The scaling laws have been validated analysing the Martian surface-layer data for the relations between the power spectra of wind and temperature turbulence and the corresponding mean values of wind speed and temperature. Usual spectral formulations were used based on the scaling laws ruling the Earth atmospheric surface layer, whereby the Earth's atmosphere is used as a standard for the Martian atmosphere.     

EPR and SQUID magnetometry study of Cu2FeSnS4 (stannite) and Cu2ZnSnS4 (kesterite)

An EPR and SQUID magnetometry study of Cu₂FeSnS₄ (stannite) and Cu₂ZnSnS₄ (kesterite) has been performed in order to gain a deeper insight into the crystal chemistry of these minerals, in which the mixed character of bonds lends uncertainty to the determination of the metal valence states. EPR investigations were performed down to almost liquid nitrogen temperature on both natural and synthetic samples of stannite and kesterite. The interpretation of their parameters (g- and T-tensors) was refined by computer simulation. The main feature of all the spectra is the unstructured signal centered at about 0.310 T due to the presence of Cu(II). The absence of structure in the signal is due to spin-spin exchange interaction between Cu(II) and Fe(II), pointing to a diluted distribution of Cu(II). The temperature dependence of the Cu(II) signal can be related to a topological variation of the first-neighbors coordination. The SQUID measurements, while allowing a more precise interpretation of the EPR data, led to a full characterization of magnetic behavior of stannite and kesterite down to liquid helium temperature, evidencing antiferromagnetic interactions between the Fe(II) ions in all samples but in synthetic kesterite. From the EPR and SQUID experimental data no evidence was provided for the existence of two different structures for stannite and kesterite. Received: 2 August 1999 / Accepted: 7 January 2000