The Relationship of Green-Line Transients to White-Light Coronal Mass Ejections

We report observations by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft of three coronal green-line transients that could be clearly associated with coronal mass ejections (CMEs) detected in Thomson-scattered white light. Two of these events, with speeds >25 km s^-1, may be classified as ‘whip-like’ transients. They are associated with the core of the white-light CMEs, identified with erupting prominence material, rather than with the leading edge of the CMEs. The third green-line transient has a markedly different appearance and is more gradual than the other two, with a projected outward speed <10 km s^-1. This event corresponds to the leading edge of a ‘streamer blowout’ type of CME. A dark void is left behind in the emission-line corona following each of the fast eruptions. Both fast emission-line transients start off as a loop structure rising up from close to the solar surface. We suggest that the driving mechanism for these events may be the emergence of new bipolar magnetic regions on the surface of the Sun, which destabilize the ambient corona and cause an eruption. The possible relationship of these events to recent X-ray observations of CMEs is briefly discussed. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1004981125702     

Some comments on the asymptotic limit of antiproton-proton flux ratio at the top of the atmosphere

Using the leaky-box model the upper limit of the antiproton-proton flux ratio at the top of the atmosphere has been estimated from the latest primary nucleon spectrum and accelerator data on inclusive reactions. The estimated value of flux ratio comes out to be (3.6±0.3)×10^–4 is in accord with the previous results but still far from the measurements.     

IGU commission health and development UGI commission sante et developpement In conjunction with medical geography specialty groups of the AAG,CAG, and IBG

The International Geographical Union Reports

IGU commission health and development UGI commission sante et developpement In conjunction with medical geography specialty groups of the AAG, CAG, and IBG International medical geography symposium     

Simulation of the ice age atmosphere — January and July means

A simulation of the atmospheric state under ice age conditions (18,000 years before present) is presented. The T21 Atmospheric General Circulation Model (AGCM), originally developed at the European Centre for Medium-Range Weather Forecasts, was used for the calculation of six annual cycles. Results of the near-surface climatology (2 m-temperature, 10 m-wind, and precipitation), averaged over the last five model years, are presented. The presentation is restricted to January and July means in order to demonstrate the glacial changes in summer and winter. The model's response to ice age boundary conditions was quite consistent with paleogeological data on land and with AGCM experiments of other studies. Although the differences between the mean climate states of the model atmosphere under glacial and modern boundary conditions were statistically significant, the basic structure of the simulated atmospheric circulation was not altered substantially.

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Zusammenfassung Eine Simulation des Zustands der eiszeitlichen Atmosphäre (18000 Jahre vor heute) wird vorgestellt. Das T21-Modell (allgemeines Zirkulationsmodell der Atmosphäre), entwickelt am Europäischen Zentrum für Mittelfrist-Wettervorhersage, wurde zur Berechnung von sechs Jahresgängen verwendet. Die Ergebnisse der oberflächennahen Klimatologie (2 m-Temperatur, 10 m-Wind und Niederschlag) werden präsentiert als Mittel über die letzten fünf Modelljahre. Die Darstellung ist eingeschränkt auf Januar- und Julimittel, um die eiszeitlichen Änderungen im Sommer und Winter deutlich zu machen. Die Antwort des Modells auf die eiszeitlichen Randbedingungen stimmt recht gut überein mit paläogeologischen Landdaten und mit anderen Simulationsrechnungen. Obgleich die Klimaunterschiede in der eiszeitlichen und der heutigen Modellatmosphäre statistisch signifikant sind, wurde die Grundstruktur der atmosphärischen Zirkulation vom T21-Modell nur wenig verändert.

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Résumé Cette note présente une simulation de l'état de l'atmosphère dans les conditions de l'âge glaciaire, il y a 18.000 ans. Le calcul de 6 cycles annuels a été effectué au moyen du modèle T 21 de la circulation atmosphérique générale développé au Centre Européen de prévision du temps à moyen terme. Les éléments du climat proche de la surface (température à 2 m, vent à 10 m, précipitations) sont présentés en moyenne des cinq dernières années du modèle. Ces éléments sont limités aux moyennes de janvier et de juillet, de manière à mettre en évidence les changements hiver/été. La réponse du modèle aux conditions aux limites de l'âge glaciaire est en bon accord avec les données paléontologiques de terrain ainsi qu'avec d'autres calculs de simulation. Bien qu'il existe d'importantes différences climatiques entre les modèles d'atmosphère de l'âge glaciaire et d'aujourd'hui, la structure de base de la circulation atmosphérique du modèle T 21 est peu modifiée.

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, 18000 . 21 = , = , 6 . , — 2 10 , 5 . , , , . . , 21 .

     

Can Brans-Dicke universes in five dimensions be interpreted as 4-dimensional general relativity cosmologies?

The 5-dimensional Jordan-Brans-Dicke cosmologies in vacuum are found for the Bianchi type I metric, their relation with general relativity cosmologies is studied. Two solutions are possible, both produce effective pressure and energy density in the 4-dimensional G.R.-universes. One is a power-law relation, with two cases, the first one is forp _eff=_eff and the other forp _eff=_eff(– 1 < < 1) has a behaviour as the open flat universe. The second solution is an exponential only valid forp _eff=–_eff. In all cases the three-space expansion reaches infinity ast and the fifth dimension can be made to decrease approaching zero. The scalar field can increase or decrease with time.     

Photometric observations of CH Cygni in the period 1978–1987. Dust matter condensation in its circumstellar envelope during 1985–1987

We present the results of the photometric observations, in theUBVRJHKLMNQ system, of CH Cyg, made in the period 1978–1987. They have shown that from 1985 to 1987 dust condensed in its circumstellar envelope have taken place the condensation of the dust matter. In 1987 its mass and temperature were about 3×10^–8 M and 800 K, respectively.     

A new approach to the possibilities of Σ(D)-dependence and distances of the supernova remnants

A new way of choosing of the calibrators for constructing (D)-dependence of supernova remnants (SNR) is suggested. A knowledge of the distance of an SNR is not sufficient to consider it as a calibrator. It is shown that neither more accurate determination of distance to calibrators, nor an increase in their number, nor an increase in the precision of the remnant angular size and radio flux determination can lead to a considerable improvement of simple (D)-dependence which is suggested in the given work.For remnants with small surface brightnesses there is no (D)-dependence at all. The most accurate remnant distances currently known, are given: these are liable to change only after a large amount of additional observational data accurately compiled.     

Isovortical orbits in uniformly rotating coordinates

For the conservative, two degree-of-freedom system with autonomous potential functionV(x,y) in rotating coordinates; $$\dot u - 2n\upsilon = V_x , \dot \upsilon + 2nu = V_y $$ , vorticity (v _x -u _y ) is constant along the orbit when the relative velocity field is divergence-free such that: $$u(x,y,t) = \psi _y , \upsilon (x,y,t) = - \psi _x $$ . Unlike isoenergetic reduction using the Jacobi, integral and eliminating the time,non-singular reduction from fourth to second-order occurs when (u,v) are determined explicitly as functions of their arguments by solving for ψ (x, y, t). The orbit function ψ satisfies a second-order, non-linear partial differential equation of the Monge Ampere type: $$2(\psi _{xx} \psi _{yy} - \psi _{xy}^2 ) - 2(\psi _{xx} + \psi _{yy} ) + V_{xx} + V_{yy} = 0$$ . Isovortical orbits in the rotating frame arenot level curves of ψ because it contains time explicitly due to coriolis effects. Rather, (x, y) coordinates along the orbit are obtained, from (u, v) either by numerical integration of the kinematic equations, or by partial differentiation of the Legendre transform ? of ψ. In the latter case, ? is shown to satisfy a non-linear, second-order partial differential equation in three independent variables, derived from the Monge-Ampere Equation. Complete reduction to quadrature is possible when space-time symmetries exist, as in the case of central force motion.     

Polarimetry of comets: A review

Some attempts of polarimetric sounding of Comet Halley will be undertaken from the flyby probes. In order to facilitate the final planning and the future interpretation of these experiments we have done a thorough analysis of practically all available polarimetric observations. An emphasis is made on interpretation attempts and their discussion. The results of the phase dependence of polarization investigations are presented covering a wide range of phase angles . The chief peculiarities of this dependence are: maximum polarization at = 90, diminishing through zero at 20, negative values up to several per cent and a final growth to zero at zero . A division into gaseous and dusty comets on polarimetric basis is revealed. The wavelength dependence of polarization is discussed. The numerous results of detailed polarimetry are compared to the negative results of attempts to detect the elliptical polarization. New observational problems arising from the evidence given by the negative polarization at small phase angles and by the opposition effect recently discovered are discussed.     

The magnetic and thermodynamical structure of a coronal hole

A nonpolytropic model of a polar coronal hole at 2 R R 5 R is constructed. Our main assumptions are: (1) the magnetic structure of the Sun can be described by a combination of dipole-like and radial fields; (2) in the magnetically dominated region [(v ²/2) < (B ²/8)] the influence of the outflow on the magnetic structure is negligible. The magnetic and thermodynamic structures are obtained by solving the force balance equation for plasma with the observationally derived electron density. Profiles of velocities in the acceleration regime are presented and the influence of the outflow on the thermodynamic structure of the solar corona above the polar region is discussed.This paper is the first part of a joint project of the Space Environment Laboratory, the Joint Institute for Laboratory Astrophysics, and the High Altitude Observatory, NCAR. The second paper by Munro and Tzur is in preparation.Work done while at the Space Environment Laboratory, NOAA, ERL, Boulder, CO 80303, U.S.A.1982–83 Visiting Fellow at the Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Visitor at NCAR.