The properties of hard X-ray emitting symbiotic stars

Hard X-ray emitting symbiotic stars are candidates for SN Ia progenitors. The importance of Type Ia SNe as standard candles for cosmology makes the study of their progenitor systems particularly important. Additionally, they provide one of the most promising laboratories for the study of astrophysical jets. Typically, the X-ray emission in these systems is modeled with a collisional plasma model, sometimes with an emission measure distribution taken from a cooling flow model. The lack of any coherent periods in both X-rays and optical wave band strongly suggests that the accreting white dwarfs in the hard X-ray symbiotic stars are non-magnetic. Although relatively few have been discovered to date, but we believe that there are very many of them in our galaxy and could be possible candidates for the Galactic Ridge X-ray Emissions (GRXE).     

Normalized ionization yield function for various nuclei obtained with full Monte Carlo simulations

Several recent results important for production of ion pairs in the Earth atmosphere by various primary cosmic ray nuclei are presented. The direct ionization by various primary cosmic ray nuclei is explicitly obtained. The longitudinal profile of atmospheric cascades is sensitive to the energy and mass (charge) of the primary particle. In this study different cosmic ray nuclei are considered as primaries, namely Helium, Oxygen and Iron nuclei. The cosmic ray induced ionization is obtained on the basis of CORSIKA 6.52 code simulations using FLUKA 2006 and QGSJET II hadronic interaction models. The energy of the primary particles is normalized to GeV per nucleon. In addition, the ionization yield function Y is normalized as ion pair production per nucleon. The obtained ionization yield functions Y for various primaries are compared. The presented results and their application are discussed.     

Clouds and Earth Radiant Energy System (CERES), a review: Past,present and future

The Clouds and Earth Radiant Energy System (CERES) project’s objectives are to measure the reflected solar radiance (shortwave) and Earth-emitted (longwave) radiances and from these measurements to compute the shortwave and longwave radiation fluxes at the top of the atmosphere (TOA) and the surface and radiation divergence within the atmosphere. The fluxes at TOA are to be retrieved to an accuracy of 2%. Improved bidirectional reflectance distribution functions (BRDFs) have been developed to compute the fluxes at TOA from the measured radiances with errors reduced from ERBE by a factor of two or more. Instruments aboard the Terra and Aqua spacecraft provide sampling at four local times. In order to further reduce temporal sampling errors, data are used from the geostationary meteorological satellites to account for changes of scenes between observations by the CERES radiometers.     

Potential of salt-accumulating and salt-secreting halophytic plants for recycling sodium chloride in human urine in bioregenerative life support systems

This study addresses the possibility of growing different halophytic plants on mineralized human urine as a way to recycle NaCl from human wastes in a bioregenerative life support system (BLSS). Two halophytic plant species were studied: the salt-accumulating Salicornia europaea and the salt-secreting Limonium gmelinii. During the first two weeks, plants were grown on Knop’s solution, then an average daily amount of urine produced by one human, which had been preliminarily mineralized, was gradually added to the experimental solutions. Nutrient solutions simulating urine mineral composition were gradually added to control solutions. NaCl concentrations in the stock solutions added to the experimental and control solutions were 9 g/L in the first treatment and 20 g/L in the second treatment. The mineralized human urine showed some inhibitory effects on S. europaea and L. gmelinii. The biomass yield of experimental plants was lower than that of control ones. If calculated for the same time period (120 d) and area (1 m²), the amount of sodium chloride taken up by S. europaea plants would be 11.7 times larger than the amount taken up by L. gmelinii plants (486 g/m² vs. 41 g/m²). Thus, S. europaea is the better choice of halophyte for recycling sodium chloride from human wastes in BLSS.     

Ionization effect of solar protons in the Earth atmosphere – Case study of the 20 January 2005 SEP event

The cosmic ray ground level enhancement on January 20, 2005 is among the largest recorded events in the history of cosmic ray measurements. The solar protons of MeV energies cause an excess of ionization in the atmosphere, specifically over polar caps following major solar disturbances. The ionization effect in the Earth atmosphere is obtained for various latitudes on the basis of solar proton energy spectra, reconstructed from GOES 11 measurements and subsequent full Monte Carlo simulation of cosmic ray induced atmospheric cascade. The estimation of ionization rates is based on a numerical model for cosmic ray induced ionization. The evolution of atmospheric cascade is performed with the CORSIKA 6.52 code using FLUKA 2006b and QGSJET II hadron interaction models. The atmospheric ion rate ionization is explicitly obtained for 40°N, 60°N and 80°N latitudes. The time evolution of obtained ion rates is presented. It is demonstrated that ionization effect is negative for 40°N and small for 60°N, because of accompanying Forbush decrease. The ionization effect is significant only in sub-polar and polar atmosphere during the major ground level enhancement of 20 January 2005.     

The Solar Sail Materials (SSM) project – Status of activities

SSM (Solar Sail Materials) is an on-going project for the European Space Agency (ESA) relying on past and recent European solar sail design projects. It aims at developing and testing future technologies suitable for large, operational solar sailcrafts.     

Radiation risk of the crew members of the expeditions on the "MIR" station during the 22nd solar activity cycle.

The radiation risk at the end of the flight was calculated for the members of the main expeditions on the "Mir" station. It was based on the absorbed dose dynamics data measured by the board dosimeter. The radiation damage models created for standards of the radiation safety of the space flights were used in the calculations. The analysis of the obtained values of the risk and its dynamics for some cosmonauts are presented in the topic. The risk values delta P are close to the limited levels given by equation of delta P = 0.6 x 10 x T(-4), [this equation appears also as delta RHrad = 0.6 x 10(-4) x T later in the text] where T--is flight duration in months.     

Biological life support for manned missions by ESA.

The anticipated evolution of life support technologies for ESA, considering both the complementary life support system requirements and the missions' characteristics, is presented. Based on these results, promising biological life support technologies for manned space missions have been selected by ESA either for their intrinsic ability and performance in effecting specific tasks for atmosphere-, water-, waste-management versus physico-chemical alternatives and/or for longer-term application to a more ecological concept (CES) focusing ultimately on food production. Actual status and plan for terrestrial and space testing of biological life support presented focusing on the "task specific" decontamination technology of the Biological Air Filter (BAF), and on food reprocessing technologies from biodegradable wastes with the MELISSA microbial ecosystem.     

Time-dependent thermal X-ray afterglows from GRBS

Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.     

XMM-Newton study of soft excess X-ray emission in clusters of galaxies

We discuss the detection of soft excess X-ray emission in a sample of 19 clusters of galaxies observed by XMM-Newton. In 6/19 clusters evidence for a soft X-ray excess is found. Four of these clusters show soft X-ray and O VII line emission from gas with a temperature of 0.2 keV. The centroid of this oxygen line is consistent with the redshift of the cluster. The intensity and spatial extend of the soft excess agrees with previous PSPC measurements. These observations are interpreted as emission from warm-hot intergalactic medium filaments, with density enhancements near the cluster centers, consistent with theoretical predictions. In the other two soft excess clusters a non-thermal origin is consistent with the data.