The masers of E-type methanol in orion KL and SGR B2

Using a simplified model the statistical equilibrium and radiative transfer equations of E-type-CH₃OH are solved for Orion KL and SgrB2. According to our calculation results and the observation data taken by Matsakiset al. (1980) and Morimotoet al. (1985a, b), the physical conditions of both sources are estimated. In theJ ₂-J ₁ E methanol maser region of Orion KL, the density, kinetic temperature, dust temperature, and the fractional abundance are 0.8–2×10⁶ cm^–3, 150, 30–90 K, 0.8–8×10^–6. In the 4_–1-3₀ E and 5_–1-4₀ E methanol maser region of Sgr B2 the correspondance physical conditions above are 10⁴ cm³, 45, 23 K, and 7×10^–7, respectively.     

Simultaneous five color (UBVRI) polarimetry of VV Puppis

Observations of linear and circular polarization in five colour bands during a highly active state of VV Puppis in January-86 are reported. A strong linear polarization pulse with the maximum in the blue, P_B22 %, is observed at the end of the bright phase when the active pole is at the limb and a weaker secondary pulse, P_B7 %, is seen in the beginning of the bright phase, when the active pole reappears. Strong positive circular polarization is also observed in the blue and the ultraviolet, P_UP_B18 %, P_V10 % during the bright phase. The circular polarization reverses the sign in the B and V bands during the faint phase and a negative polarization hump is seen when the active pole crosses the limb. The circular polarization in the V band reaches the value P_V–10% at the hump, after which it remains near P_V–5% during the faint phase. This is probably due to radiation coming from the second, less active pole and accretion thus takes place onto both poles. The wavelength dependences of the positive and negative parts of the circular polarization curve are different and no polarization reversal is seen in the U band. The position angle of the linear polarization is well determined during a large portion of the cycle, especially in the V band, thanks to the activity from both poles. A best fit to the position angle curve, taking into account also the duration of the positive circular polarization phase interval =0.40 (in the V band), yields the values of orbital inclination i=78°±2° and the colatitude of the active magnetic pole =146°±2°. The relatively good fit to the position angle data indicates that the simple dipole model is nearly correct in the case of VV Puppis. Some wavelength dependence is, however, seen in the position angle curves, especially in the I band where the slope / at the main pulse is considerably smaller than in the other bands. The shape of the position angle curves changes also in the blue and the ultraviolet around the middle of the bright phase. This is probably due to optical thickness effects as the side of the accretion column which is toward the observer changes near this phase.Based on observations made at the European Southern Observatory, La Silla, Chile.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.On leave from University of Helsinki Observatory     

Atomic data relevant to line formation in strongly magnetized white dwarf stars

The discovery of magnetic field strengths in the range of 500 million Gauss in the objects Grw+70°8247 and PG1031+224 has given enormous impetus to investigations of magnetic white dwarf stars. We have determined intensities of Balmer transitions for B>10⁸ Gauss as a function of field and find strong oscillations of the transitions strengths, which are of importance to the quantitative analysis of the observed spectra and the interpretation of polarimetric measurements in these objects.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

On a sequence of remarkable fine structures in the type IV burst of 24 April, 1985

During the type IV burst on 24 April, 1985 we observed at 234 MHz an untypical, strong, nearly six hours lasting continuum emission incorporating several groups of broadband pulsations, zebra patterns, fiber bursts, and a new fine structure phenomenon. The power spectra of the groups of broadband pulsations reveal no simple structure. There is only one common periodic component between 0.3 s and 0.4 s. Slowly drifting chains of narrowband fiber bursts are described as a new fine structure by spectrograms and simultaneously recorded single frequency intensity profiles. A qualitative model of this new fine structure is suggested.     

Ultraviolet solar irradiance measurement from 200 to 358 nm during spacelab 1 mission

The paper presents the results obtained from the UV-spectrometer of the Solar Spectrum Experiment during the Spacelab 1 mission in December 1983. The irradiance data concern 492 passbands, which are located between 200 and 358 nm at almost equidistant wavelengths separated by about 0.3 nm. The passbands have a well-defined, bell-shaped profile with a full width at half maximum of about 1.3 nm. The data, which have an error budget between 4 and 5%, agree closely with the spectral distributions observed by Heath (1980) and Mentall et al. (1981) and confirm that the solar irradiance and the fluxes of Sun-like stars show about the same spectral distribution down to at least 240 nm.     

Observations of longperiod mass velocity oscillations in the Sun's chromosphere

Observations made by the differential method in the H line have revealed longperiod (on a timescale of 40 to 80 min) line-of-sight velocity oscillations which increase in amplitude with distance from the centre to the solar limb and, as we believe, give rise to prominence oscillations. As a test, we present some results of simultaneous observations at the photospheric level where such periods are absent.Oscillatory processes in the solar chromosphere have been studied by many authors. Previous efforts in this vein led to the detection of shortperiod oscillations in both the mass velocities and radiation intensity (Deubner, 1981). The oscillation periods obtained do not, normally, exceed 10–20 min (Dubov, 1978). More recently, Merkulenko and Mishina (1985), using filter observations in the H line, found intensity fluctuations with periods not exceeding 78 min. However, the observing technique they used does not exclude the possibility that those fluctuations were due to the influence of the Earth's atmosphere. It is also interesting to note that in spectra obtained by Merkulenko and Mishina (1985), the amplitude of the 3 min oscillations is anomalously small and the 5 min period is altogether absent, while the majority of other papers treating the brightness oscillations in the chromosphere, do not report such periods in the first place. So far, we are not aware of any other evidence concerning the longperiod velocity oscillations in the chromosphere on a timescale of 40–80 min.Longperiod oscillations in prominences (filaments) in the range from 40 to 80 min, as found by Bashkirtsev et al. (1983) and Bashkirtsev and Mashnich (1984, 1985), indicate that such oscillations can exist in both the chromosphere and the corona (Hollweg et al., 1982).In this note we report on experimental evidence for the existence of longperiod oscillations of mass velocity in the solar chromosphere.     

Recent trends in Siberian urban growth

Future trends in urbanization in the USSR east of the Urals are considered using official Soviet data from 1959 to 1985. "Absolute and relative growth and growth rates are calculated for economic regions, oblast-level administrative entities, and individual cities, as well as for city-size categories. The nature of Siberian growth suggests that in addition to serving as centers of resource exploitation, Siberian cities also function as growth poles for more integrated development. The analysis serves as the preliminary stage for proposed future research on the extent of Siberian urban development and the integration of Siberia into the Soviet economy."     

The Soviet settlement system--current issues and future prospects

"A survey of current urban issues and trends in the Soviet Union sets the stage for an analysis of the problems of the urban system of the USSR and discussion of recent efforts at planning and policy development for a national settlement system. The General Scheme of Settlement, issued in 1975 and revised in 1982 to guide the development of such a national system, is examined as is the ensuing debate between two opposing schools of thought as to the best approach for restructuring the urban system."     

Pleistocene mass-flow deposits of basaltic hyaloclastite on a shallow submarine shelf,South Iceland

A Pleistocene subaqueous, volcanic sequence in South Iceland consists of flows of basaltic hyaloclastite and lava with interbedded sedimentary diamictite units. Emplacement occurred on a distal submarine shelf in drowned valleys along the southern coast of Iceland. The higher sea level was caused by eustatic sea-level change, probably towards the end of a glaciation. This sequence, nearly 700 m thick, rests unconformably on eroded flatlying lavas and sedimentary rocks of likely Tertiary age. A Standard Depositional Unit, describing the flows of hyaloclastite, starts with compact columnar-jointed basalt overlain by cubejointed basalt, and/or pillow lava. This in turn is overlain by thick unstructured hyaloclastite containing aligned basalt lobes, and bedded hyaloclastite at the top. A similar lithofacies succession is valid for proximal to distal locations. The flows were produced by repeated voluminous extrusions of basaltic lava from subaquatic fissures on the Eastern Rift Zone of Iceland. The fissures are assumed to lie in the same general area as the 1783 Laki fissure which produced 12 km³ of basaltic lava. Due to very high extrusion rates, the effective water/melt ratio was low, preventing optimal fragmentation of the melt. The result was a heterogeneous mass of hyaloclastite and fluid melt which moved en masse downslope with the melt at the bottom of the flow and increasingly vesicular hyaloclastite fragments above. The upper and distal parts of the flow moved as low-concentration turbulent suspensions that deposited bedded hyaloclastite.     

Transfer factors of contamination between the German Bight and its tributary waters derived from measured tritium and Cs-137 activity concentrations

Summary Evaluation of the results of radioactivity monitoring in the southern North Sea between 1977 and 1987 has shown that in the water of the German Bight three areas stand out due to their different ratios between salinity and concentration of dissolved Cs-137 and tritium. While salinity steadily increases with greater distance from the coast, the Cs-137 concentration above 34 PSU (Practical Salinity Unit) increases sharply and shows how far water from the western and central North Sea, contaminated by nuclear reprocessing in Sellafield (Irish Sea), reaches into the German Bight. In the 34 to 32.5 PSU range, the influence can be seen of water contaminated by tritium originating in the rivers Rhein, Maas and Schelde, precipitation and the nuclear reprocessing plant at La Hague (Channel). Below 32.5 PSU, the influence of the influx from the rivers Elbe, Weser and Ems becomes apparent. These rivers are less contaminated with tritium.Assuming that Cs-137 and tritium, like the salinity of sea water, behave conservatively and that the decay-time of these two isotopes is long compared with the time-scale of water exchange in the southern North Sea, the concentration values measured are used to calculate the structure of the water masses in the three areas of the German Bight mentioned above using the mixing principle. Evaporation is taken into account. Results show that beyond 34 PSU, about half the sea water originates in the western central North Sea while the other half comes from the Channel. Below 34 PSU, the first mentioned share amounts only to a few per cent. Results also show that fresh water from the Rhein delta and precipitation, increasing with a decrease in salinity from 34 to 32.5 PSU, accounts for a maximum of 5% each. The fresh water influx into the German Bight via the rivers Elbe, Weser and Ems amounts to app. 11% when the PSU value reaches 29. The calculated portions are the mean values for the observation period. The number of measurements available makes it impossible to distinguish more exactly between the temporal and spatial variability of the amounts of the individual components.The quantity of each calculated portion of sea water also represents the transfer factor of concentration between the nuclide concentration in the source (e. g. the Rhein) and the concentration in the German Bight. In addition, these factors are used to calculate the transfer factors of discharge using the annual drainage rates of the sources. Thus a radioactive discharge rate of 10¹⁵ Bq per year into the Rhein would produce a mean activity concentration of 0.34 Bq/l in the German Bight (at a salinity of 33.5 PSU). To verify the calculated transfer factors, tritium concentrations in the German Bight are derived from existing environmental tritium data and the results are compared with the values actually measured.

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Transferkaktoren zwischen der Deutschen Bucht und ihren Zuflüssen abgeleitet aus der Tritium- und Cs-137-Aktivitätskonzentration in den beteiligten Gewässern

Zusammenfassung Eine zusammenhängende Auswertung der Meßergebnisse der Radioaktivitätsüberwachung in der südlichen Nordsee über den Zeitraum 1977 bis 1987 hat gezeigt, daß im Wasser der Deutschen Bucht deutlich drei durch den Salzgehalt des Meerwassers und die Konzentration der gelösten Radionuklide charakterisierte Bereiche zu unterscheiden sind.Während der Salzgehalt mit wachsender Entfernung von der Küste stetig zunimmt, steigt die Cs-137-Konzentration oberhalb 34 PSU (Practical Salinity Unit) sprunghaft an und signalisiert die Grenze, bis zu der das durch die Kernbrennstoff-Wiederaufarbeitung in Sellafield (Irische See) kontaminierte Meerwasser der westlichen und mittleren Nordsee in die Deutsche Bucht vordringt. Im Bereich 34 bis 32,5 PSU ist das von Westen zugeführte, stärker Tritium-kontaminierte Wasser aus Rhein, Maas, Schelde und atmosphärischem Niederschlag zu erkennen, an das sich unterhalb 32,5 PSU der geringer mit Tritum kontaminierte Zufluß aus Elbe, Weser und Ems anschließt.Davon ausgehend, daß sich Cs-137 und Tritium wie der Salzgehalt im Meerwasser konservativ verhalten und daß weiterhin die Halbwertzeit des radioaktiven Zerfalls dieser beiden Nuklide lang ist gegenüber den Wasseraustauschzeiten im betrachteten Meeresgebiet, wurden die in der südlichen Nordsee gemessenen sowie aus der Literatur für den Süßwasserbereich entnommenen Konzentrationswerte dazu genutzt, um rechnerisch mit Hilfe des Mischungsgesetzes den Wassermassenaufbau in den drei genannten Salinitätsbereichen in der Deutschen Bucht quantitativ zu bestimmen. Es zeigte sich, daß oberhalb von 34 PSU das Meerwasser aus etwa gleichen Teilen aus der westlichen/mittleren Nordsee und dem Kanal stammt, während unterhalb dieser Salzgehaltsgrenze nur noch mit wenigen Prozentanteilen Wasser aus der mittleren Nordsee zu finden ist. Ferner ergab sich, daß das aus dem Rheinmündungsbiet bzw, aus dem atmosphärischen Niederschlag stammende Süßwasser — mit sinkendem Salzgehalt steigend — bei 32,5 PSU einen maximalen Anteil von jeweils 5% an Meerwasser hat. Der direkte Süßwasserzufluß aus Elbe, Weser und Ems beträgt in die Deutsche Bucht bei 29 PSU ca. 11%.Die berechneten Anteile sind Mittelwerte über den gesamten Beobachtungszeitraum; die Anzahl der Messungen läßt eine genauere Unterscheidung in zeitliche und räumliche Variabilität der Zusammensetzung nicht zu.Die Größe des jeweils bestimmten Anteils am Meerwasser stellt gleichzeitig den Transferfaktor der Konzentration zwischen der Nuklidkonzentration im Ursprungsgewässer (z. B. dem Rhein) und der sich daraus einstellenden Konzentration in der Deutschen Bucht dar. Ferner wurden die Transferfaktoren der Konzentration in Verbindung mit aus der Literatur entnommenen Größen der jährlichen Abflußmengen der Ursprungsgewässer genutzt, um auch die Transferfaktoren der jährlichen Einbringung zu ermitteln. So ergibt die jährliche Einbringung von 10¹⁵ Bq eines Nuklides z. B. in den Rhein bei 33,5 PSU in der Deutschen Bucht eine mittlere Konzentration von 0,34 Bq/l.Als Anwendungsbeispiel und zur Überprüfung der Richtigkeit der Transferfaktoren wird die Auswertung des Tritiumauslasses bei La Hague auf die Deutsche Bucht berechnet und mit den gemessenen Werten verglichen.