Search for low energyν e,μ,τ andv e,μ,τ in coincidence with BATSE gamma ray bursts

A search for low energy neutrinos of all flavours in correlation with 553 ray bursts detected by BATSE aboard the Compton Observatory has been performed by the LSD (Liquid Scintillator Detector) neutrino telescope. No excess ofe,, orv _e,, candidate has been detected by LSD during the time interval in which BATSE detected the 90% of the photon flux for any of the GRBs analyzed. Upper limits on the neutrino fluxes are given in the paper.     

Numerical simulation of the general circulation of the atmosphere of Titan

The atmospheric circulation of Titan is investigated with a general circulation model. The representation of the large-scale dynamics is based on a grid point model developed and used at Laboratoire de Météorologie Dynamique for climate studies. The code also includes an accurate representation of radiative heating and cooling by molecular gases and haze as well as a parametrization of the vertical turbulent mixing of momentum and potential temperature. Long-term simulations of the atmospheric circulation are presented. Starting from a state of rest, the model spontaneously produces a strong superrotation with prograde equatorial winds (i.e., in the same sense as the assumed rotation of the solid body) increasing from the surface to reach 100 m sec-1 near the 1-mbar pressure level. Those equatorial winds are in very good agreement with some indirect observations, especially those of the 1989 occultation of Star 28-Sgr by Titan. On the other hand, the model simulates latitudinal temperature contrasts in the stratosphere that are significantly weaker than those observed by Voyager 1 which, we suggest, may be partly due to the nonrepresentation of the spatial and temporal variations of the abundances of molecular species and haze. We present diagnostics of the simulated atmospheric circulation underlying the importance of the seasonal cycle and a tentative explanation for the creation and maintenance of the atmospheric superrotation based on a careful angular momentum budget.     

Effects of hall current on the hydromagnetic free convection with mass transfer in a rotating fluid

An exact analysis of Hall current on hydromagnetic free convection with mass transfer in a conducting liquid past an infinite vertical porous plate in a rotating fluid has been presented. Exact solution for the velocity field has been obtained and the effects ofm (Hall parameter),E (Ekman number), andS _c (Schmidt number) on the velocity field have been discussed.Nomenclature C species concentration - C _w concentration at the porous plate - C species concentration at infinity - C _p specific heat at constant pressure - D chemical molecular diffusivity - g acceleration due to gravity - E Ekman number - G Grashof number - H ₀ applied magnetic field - j _x, j_y, j_z components of the current densityJ - k thermal conductivity - M Hartman number - m Hall parameter - P Prandtl number - Q heat flux per unit area - S _c Sehmidt number - T temperature of the fluid near the plate - T _w temperature of the plate - T temperature of the fluid in the free-stream - u, v, w components of the velocity fieldq, - U uniform free stream velocity - w ₀ suction velocity - x, y, z Cartesian coordinates - Z dimensionless coordinate normal to the plate. Greek symbols coefficient of volume expansion - ^* coefficient of expansion with concentration - _e cyclotron frequency - dimensionless temperature - ^* dimensionless concentration - v kinematic viscosity - density of the fluid in the boundary layer - coefficient of viscosity - _e magnetic permeability - angular velocity - electrical conductivity of the fluid - _e electron collision time - _u skin-friction in the direction ofu - _v skin-friction in the direction ofv     

Motions in the solar atmosphere associated with the white light flare of 11 July 1978

Series of white light heliograms and oft- and on-band H filtergrams have been obtained, with an average spatial resolution of 1, to study the flare active McMath region 15403 on 11 July, 1978. A great number of accurate heliographic positions were determined for the umbrae, the white light flare patches and several bright H flare knots, as well as along the principal zero filament and an arch prominence. Using the measured heliographic coordinates of these objects their motions could be analyzed in some detail. The velocities of several different objects could be deduced from the coordinates. Since the heliocentric angle of the region was about 45°, the variation in apparent heliographic coordinates also enabled some variations in heights to be determined.It is pointed out that the flare when fully developed, consisted almost entirely of loops. The zero filament which was activated prior to the flare ran between two umbrae of common penumbra and opposite polarity, one belonging to an old, the other to a new spot group. The white light flare developed on both sides of the filament where it passed between these two umbrae; it was also the place where the flare started. Observational evidence appears to indicate that the erupted filament re-formed from below.An indication has been found that there was a link between the motion of some umbrae and the major flare occurrence.     

Energetic properties of interplanetary plasma at the earth's orbit following the August 4, 1972 flare

Solar wind and interplanetary magnetic field data were obtained by the PROGNOZ 1 and PROGNOZ 2 satellites during the period following the August 4, 1972 (0621 UT) solar flare. A thermalized plasma was recorded one hour after the shock followed two hours later by the plasma piston with a bulk velocity higher than 1700 km s^-1. The comparison between the PROGNOZ and PIONEER 9 solar wind data shows an attenuation of the plasma properties with the deflection from the flare's meridian.     

TREK: A cosmic-ray experiment on the Russian space station MIR

The goals of the TREK experiment, now in place on the MIR Space Station, are to resolve and measure the composition of both odd-Z and even-Z cosmic-ray nuclei up to uranium, to measure the isotopic composition of Fe-group nuclei, and to search for transuranic nucleic and exotic particles such as strangelets. To collect tracks of ultraheavy cosmic rays, exterior panels holding an array of BP-1 phosphate glass 1.2m² in area and 16 plates thick are now mounted outside the Kvant-2 module on MIR. Heaters and relays regulate the temperature of the glass at 25°±5°C. The detectors will record 10³ cosmic-ray tracks withZ50 during 2.5 years. An interior panel consisting of an array 0.09 m² in area and 32 plates thick and mounted on the inside wall of the Soyuz spacecraft (attached to the Space Station) will collect tracks of about 13000 Fe and 500 Ni nuclei.     

Solar-type stars in Cepheus OB 2: Hα emission stars and IRAS point sources

A survey for emission line stars was carried out in 1980 with the Schmidt telescope of Konkoly Observatory in the region of IC 1396 (Kun, 1986a, hereafter referred to as Paper I). This work was aimed at a preliminary mapping of the probable medium mass members of the association Cepheus OB 2. The stars of the region have been followed since then with the same telescope in order to obtain a more complete view on the stellar content of this giant star-forming region. The common variability of the H emission strength makes the sense of repeating such surveys. The new survey resulted in the discovery of 65 further emission stars. Equatorial coordinates and finding charts are given for them.PhotographicBVRI photometry was carried out for all known emission stars of the field. The colourmagnitude and two-colour diagrams derived from theB, V, R, andI magnitudes show that these stars are probably F-G-type (1.5M <M<3M ), partly pre-Main-Sequence members of Cep OB 2, whereas a few of them may be distant red giants.The youngest objects of the region can be found among the IRAS point sources. Their properties are discussed on the basis of IRAS data alone.     

Photoelectron fluxes in cometary atmospheres

The photoelectron fluxes in cometary atmospheres are calculated by a Monte Carlo method. This is the first quantitative model calculation of this kind. A pure H₂O atmosphere is assumed with a sublimation rate of 10³⁰ molecules sec^?1 at 1 AU. Discussions of the energetics of electron gas and of the elementary collisional processes in determining the fluxes largely concern this water atmosphere. Influences on the photoelectron fluxes are also investigated for CO, another possible constituent. The excitation rate of the ${}^1\text{D}$ level of atomic oxygen in electron impacts is evaluated. It is highly improbable that the photoelectrons are responsible for the observed 6300 Å emission of the order of 1 kR at a heliocentric distance of 1 AU. The structure of the heat equation for thermal electrons is analyzed and a drastic change of the plasma behavior within the coma region is expected.