The search for hot spots associated with the Cygnus X-3 relativistic jet

We report and shortly discuss here the observational work carried out in order to test the possibility that two previously detected radio sources, in the vicinity of the well known microquasar Cygnus X-3, could be hot spot tracers of interaction between its relativistic jet and the interstellar medium (ISM). The motivation behind this search is in part justified considering recent theoretical models of high energy γ-ray emission which strongly rely on the interaction sites of galactic relativistic jets with nearby ISM clouds. The results presented in this paper include an improved radio exploration of the several arc-minute field around Cygnus X-3 using the Very Large Array (VLA), as well as deep near infrared (NIR) imaging with the Calar Alto 3.5 m telescope. We anticipate here that our observations do not appear to support the initial hot spot hypothesis. Instead, the resulting images suggest that the two radio sources, originally believed to be hot spot candidates, are most likely background or foreground objects.     

Bianchi type-IX cosmic strings in a scalar-tensor theory of gravitation

Bianchi type-IX space-time is considered in the presence of cosmic string source in the frame work of a scalar- tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A 113:467, 1985). Exact cosmological models representing geometric (Nambu) string, p string and baratropic string are discussed in this theory. Some physical and kinematical properties of the models are also studied.     

Dynamics of line-of-sight velocities and magnetic field in the solar photosphere during the formation of the large active region NOAA 10488

Analysis of SOHO longitudinal magnetograms and Dopplergrams has revealed the appearance of a region of enhanced upflow of matter in the photosphere when the top of a loop-shaped magnetic flux tube forming a large active region passed through it. The maximum upflow velocity reached 2 km s^?1, the maximum size exceeded 20 000 km, and the lifetime was about 2 h.     

Twist transport in strongly torsioned astrophysical flux tubes

Riemannian geometrical effects on the expansion of the electron magnetohydrodynamical (EMH) superconductivity modeled twisted nonplanar thin magnetic flux tubes are considered. A solution is found which represents almost incompressible plasma flows, where the twist of flux tube is computed in terms of the continuous variation of its cross-section. It is shown that the twist increases in regions where twisted flux tube expands as in Parker’s conjecture. From computation of compression along the tube we show that when the torsion is weak a centrifugal or vorticity effect on the longitudinal direction of the tube enhances the screening effect on the “superconductor”. Throughout the paper we consider helical flux tubes where torsion and curvature of the tube are constants. Thus we show that the Parker’s conjecture is valid in a continuos manner for these type II superconducting twisted flux tubes. Throughout the paper we adopt the approximation that the radial component of the magnetic field varies so slowly along the tube axis that it can be approximated to zero along the tube. It is suggested that the models discussed here may also be applied to DNA and nanotubes.     

Lunar surface agglutinates: Mapping composition anomalies

From the Clementine UVVIS imagery of the lunar surface, the abundance of agglutinates in the lunar regolith and their composition in terms of FeO and Al₂O₃ oxides have been predicted. Data on the spectral, chemical, and mineralogic measurements of about 30 lunar soil samples from the Lunar Samples Characterization Consortium (LSCC) collection were used. The fulfilled prognosis confirms that the mare agglutinates are enriched in Al₂O₃ and depleted of FeO, while the highland agglutinates are depleted of Al₂O₃ and enriched in FeO. This behavior can be caused by the global transport of the lunar surface material induced by cosmogenic factors.     

Estimating average shock pressures recorded by impactite samples based on universal stage investigations of planar deformation features in quartz—Sources of error and recommendations

Planar deformation features (PDFs) in quartz are the most widely used indicator of shock metamorphism in terrestrial rocks. They can also be used for estimating average shock pressures that quartz-bearing rocks have been subjected to. Here we report on a number of observations and problems that we have encountered when performing universal stage measurements and crystallographically indexing of PDF orientations in quartz. These include a comparison between manual and automated methods of indexing PDFs, an evaluation of the new stereographic projection template, and observations regarding the PDF statistics related to the c-axis position and rhombohedral plane symmetry. We further discuss the implications that our findings have for shock barometry studies. Our study shows that the currently used stereographic projection template for indexing PDFs in quartz might induce an overestimation of rhombohedral planes with low Miller–Bravais indices. We suggest, based on a comparison of different shock barometry methods, that a unified method of assigning shock pressures to samples based on PDFs in quartz is necessary to allow comparison of data sets. This method needs to take into account not only the average number of PDF sets/grain but also the number of high Miller–Bravais index planes, both of which are important factors according to our study. Finally, we present a suggestion for such a method (which is valid for nonporous quartz-bearing rock types), which consists of assigning quartz grains into types (A–E) based on the PDF orientation pattern, and then calculation of a mean shock pressure for each sample.