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A simulation study and experimental data of the CRRES G-9 ionospheric barium release are presented. The simulation study is based on a 2D electrostatic code that incorporates time-dependent coupling to the background plasma. It is shown that the densest portion of the barium ion cloud 'skids' about 15 km within the first three seconds following the release, consistent with the optical data analyses.
A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.
The abundances of C, O, Al, Ca, iron-peak and s-process elements have been derived from high-resolution spectra for a sample of stars classified as F str lambda 4077 by Bidelman. Among the 20 stars mentioned by Bidelman, we have discovered 8 barium dwarfs (or CH subgiants, according to Bond's terminology), while a 9th star, HD 182274, was already known as a CH subgiant. In addition, we have analyzed three barium stars taken from the list of Lu et al. (1983) which are probably dwarfs rather than giants, and three CH subgiants. The other 11 F str lambda 4077 stars resemble either the delta Delphini stars, since their iron abundance is enhanced while Ca is normal, or are probably spectrum composites. A few Am, Ap, lambda Bootis and normal stars have been analyzed for comparison. In particular, we have included three lambda Boo candidates, selected from their photometric properties, and their iron deficiency is confirmed. The spectroscopic, photometric and statistical evidences concerning the Ba dwarfs, support the idea that these stars may be the main sequence counterparts, and possibly the progenitors of the Ba giants. The C/O ratio varies in these stars from normal values to a maximum of 1.5, but mostly within 0.6 and 1.2. Some of these objects may therefore be considered, in this sense, as carbon stars. On the other hand, the abundances of carbon and s-process elements relative to iron are inversely correlated with metallicity, and may even exceed significantly those of typical, solar-metallicity carbon stars. Metal-deficient C stars must therefore have (C/Fe) greater than or approximately equal to 1 and (s/Fe) greater than or approximately equal to 1.5 as soon as (Fe/H) less than or approximately equal to -1. The neutron exposure is shown to increase when the metallicity decreases, which is compatible with the C-13 (alpha, n) O-16 neutron source, but not with the Ne-22 (alpha, n) Mg-25 one. The evolutionary state (within the main sequence) of the Ba dwarfs, is rediscussed in relation with their photometric and spectroscopic surface gravity, but it remains unclear.
Isotopic composition of barium and cesium in stone meteorites
Barium concentration distribution in the chondrite appear to be log-normal in shape with a median of 4.5 ppm as determined by spectrographs of 95 stony meteorites
Equilibrium of barium in solar atmosphere
Interference phenomena during X-ray scattering from barium stearate films, giving thickness measurements
Barium thin film reflection coefficient for ultraviolet radiation in ultrahigh vacuum
Ionic conductivity of solid barium fluoride
Self-lubricating composite materials prepared by vacuum impregnating nickel-chromium alloy with barium fluoride-calcium fluoride eutectic composition
Optical constants of silver and barium in vacuum ultraviolet spectral region
Strain-free electro-optic effect in single crystal barium titanate as function of temperature between 10 and 120 degrees C
Mass spectrometric stable isotope dilution method for barium determination in G-1 and W-1 rock standards
Rapid technique for liquid scintillation counting of carbon-14-labelled barium carbonate
Electro-optic effect in single crystal barium titanate
Rare earth and barium abundances in Bununu howardite
Optical properties of evaporated barium films investigated at various wavelengths, using ultrahigh vacuum reflectometer
Self-lubricating properties of composites of porous nickel and nickel-chromium alloy impregnated with barium fluoride-calcium flouride eutectic