Analysis of observations of linear polarization for <Emphasis Type="Italic">H</Emphasis><Subscript>α</Subscript> emission of flares and moustaches

In this paper we summarize and analyze the results of observation of linear polarization of H _α emission for solar flares and moustaches obtained earlier. Basic structural and evolutional properties of the observed polarization are formulated and presented. A conclusion is drawn that polarization data obtained from rough time and spatial averaging of Stokes parameters distort the true picture of polarization of H _α emission in flares and moustaches.     

On the nature of polar cap magnetic activity during undisturbed periods

The correlation between the polar cap geomagnetic variations (H-traces) and the changes of the azimuthal (Y_SE) and vertical (Z_SE) components of the interplanetary magnetic field (IMF) during undisturbed periods is examined. It is shown that peak-to-peak correlation between Y_SE and geomagnetic horizontal component variations may be generally observed in the daytime cusp region, independently of the magnitude and polarity of the Z_SE. The existence of the DP₃ disturbances associated with the northward component Z_SE > 0 is confirmed. It is shown that the disturbances due to the vertical component of the IMF dominate in the region near the pole. In so far as the southward component of the IMF generates both polar cap disturbances and geomagnetic substorms, the disturbances in the region near the pole, associated with Z_SE < 0, may be regarded as a precursor of a substorm. On this basis a new index of the polar cap magnetic activity PC_L, characterizing the changeability of the magnetic field is proposed. It is shown that the increase of the PC_L index is followed in 1–2 hr by a substorm in 70% of events considered.     

Observations of radio emission from the cosmic gamma-ray burst GRB 030329

We present the radio observations of the afterglow from the intense cosmic gamma-ray burst GRB 030329 performed with the radio telescopes of the Institute of Applied Astronomy, Russian Academy of Sciences, at the Svetloe (λ=3.5 cm) and Zelenchuk (λ=6 cm) Observatories. The difference between the fluxes measured in two different polarization modes suggests the existence of a circular polarization in the radio afterglow from GRB 030329. However, since the measurement errors of the fluxes with different circular polarizations are large, we cannot draw a firm conclusion about its detection; we can only set an upper limit on its value. An analysis of the possible generation mechanisms for the circular polarization of the relativistic jet suggests that there is a helical magnetic field in the jet. The existence of significant flux densities at various wavelengths during a long (≥10 days) period leads us to conclude that the hydrodynamic evolution of the relativistic bow shock takes place in the stellar wind, not in the interstellar medium. We have estimated the total GRB energy (E=10⁵¹ erg) (under the assumption of isotropic radiation) and the plasma density of the stellar wind from the presupernova (n=3 cm^?3). The magnetic-field strength in the relativistic jet can be estimated as B≈100 G.     

Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates

Abstract– Xenon‐isotopic ratios, step‐heating release patterns, and gas concentrations of mineral separates from Martian shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of Martian atmospheric xenon are similar in mineral separates from all meteorites, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the Martian and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, Martian atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both Martian and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the Martian component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable ¹²⁹Xe from the Martian atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock’s parent melt. Variable contents of excess ¹²⁹Xe contrast with previously reported consistent concentrations of excess ⁴⁰Ar, suggesting distinct sources contributed these gases to the parent magma.     

Detection of individual normal modes of oscillation of the Sun in the period range from 2 hr to 10 min in solar diameter studies

Solar Physics - New observations of solar oscillations are reported. Power density spectra derived from these observations reveal narrow-band oscillations that are spatially global, have spatial...     

Rapid neutron capture in supernova explosions

The implications of recent studies of the dynamics of the cores of highly evolved massive stars are considered with regard to the general problems of nucleosynthesis. The typical conditions estimated for these models are shown to be very promising for the process of element synthesis by neutron capture on a fast time scale (ther-process ofBurbidge et al., 1957).     

EChO payload electronics architecture and SW design

EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer, covering the wavelength range from 0.55 μ m to 11.0 μ m. The baseline design includes the goal wavelength extension to 0.4 μ m while an optional LWIR module extends the range to the goal wavelength of 16.0 μ m. An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem interfacing the spacecraft and collecting data from all the payload spectrometers modules. ICU is in charge of two main tasks: the overall payload control (Instrument Control Function) and the housekeepings and scientific data digital processing (Data Processing Function), including the lossless compression prior to store the science data to the Solid State Mass Memory of the Spacecraft. These two main tasks are accomplished thanks to the Payload On Board Software (P-OBSW) running on the ICU CPUs.     

Modulational instability of ion-acoustic soliton in electron-positron-ion plasma with dust particulates

Theoretical investigation has been made to study the envelope excitations of ion-acoustic solitons (IAS) in plasma composed of electrons, positrons, ions and dust particles. A nonlinear Schrödinger equation which describes the modulational instability of the IAS is derived by using the multiple scale method. The dispersive and nonlinear coefficients are obtained which depend upon the temperature of the ions, concentration of the positrons, electrons and dust particles. The modulationally stable and unstable regions are studied numerically for a wide range of parameters. It is found that these parameters play significant role in the formation of bright and dark envelope solitons in this plasma system.