منابع مشابه
STRONG MgII SYSTEMS IN QUASAR AND GAMMA-RAY BURST SPECTRA
The incidence of strong MgII systems in gamma-ray burst (GRB) spectra is a few times higher than in quasar (QSO) spectra. We investigate several possible explanations for this effect, including: dust obscuration bias, clustering of the absorbers, different beam sizes of the sources, multiband magnification bias of GRBs, association of the absorbers with the GRB event or the circumburst environm...
متن کاملCrystal structure of K0.75[FeII 3.75FeIII 1.25(HPO3)6]·0.5H2O, an open-framework iron phosphite with mixed-valent FeII/FeIII ions
Single crystals of the title compound, potassium hexa-phosphito-penta-ferrate(II,III) hemihydrate, K0.75[Fe(II) 3.75Fe(III) 1.25(HPO3)6]·0.5H2O, were grown under mild hydro-thermal conditions. The crystal structure is isotypic with Li1.43[Fe(II) 4.43Fe(III) 0.57(HPO3)6]·1.5H2O and (NH4)2[Fe(II) 5(HPO3)6] and exhibits a [Fe(II) 3.75Fe(III) 1.25(HPO3)6](0.75-) open framework with disordered K(+) ...
متن کاملTri-μ-ethanethiolato-bis{[η5-1,2,3,4-tetramethyl-5-(trimethylsilyl)cyclopentadienyl]iron(II,III)}(FeII–FeIII)
The title complex, [Fe(2)(C(2)H(5)S)(3)(C(12)H(21)Si)(2)], has an unusual Fe(2)S(3) core. The two 1,2,3,4-tetra-methyl-5-(trimethyl-silyl)cyclo-penta-dienyl (Cp') ligands coordinate to the Fe atoms with their C(5) planes perpendicular [dihedral angles = 88.23 (7) and 88.55 (7)°] to the Fe-Fe vector, building two Cp'Fe subunits. These two subunits are bridged by three thiol-ate ligands. There ar...
متن کاملSimultaneous Spectrophotometric Determination of Fe and Fe in Pharmaceuticals by Partial Least Squares with Chromogenic Mixed Reagents
Simultaneous determination of FeII and FeIII mixtures by spectrophotometric methods is a difficult problem in analytical chemistry because of spectral interferences. By multivariate calibration methods, such as partial least squares (PLS), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. The method is based on developing the re...
متن کاملCentral quasi - emission peaks in shell spectra and the rotation of disks of Be stars ?
New high-resolution echelle spectra are presented for all 6 B-type stars currently known to exhibit so-called central quasi-emission peaks (CQE’s). Empirical requirements are derived on the circumstances which favour the appearance of such features. The presence of a circumstellar disk seen edge-on is the most important. Furthermore, the disk should be optically thin in the continuum, have a sm...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1994
ISSN: 0074-1809
DOI: 10.1017/s0074180900215027