Model of Formation and Development of Spring Thermal Bar

A mathematical model simulating the thermo- and hydrodynamic processes near the thermal bar in the period of lake warming in spring is considered. A closed system of Reynolds type equations is constructed based on the Navier–Stokes nonlinear system of equations using the Boussinesq approximation and a special technique for isolating large-scale structures in turbulent medium. The turbulent viscosity coefficient is evaluated in the course of problem solution. The results of calculations are shown to agree well with field observation data.     

Hydrothermal Mineralization in the Sierra Leone Fracture Zone (Central Atlantic Ocean)

The analysis of data on the location of hydrothermal fields, seismicity, and satellite altimetry evidences that in mid-ocean ridges with low spreading velocity hydrothermal fields tend to be grouped in areas with generally low seismic activity and at intersections of discontinuities and rift zones. Based on this assumption, the Sierra Leone Fracture Zone was studied in 2000 during cruise 22 of the R/V Akademik Nikolaj Strakhov.The study of gabbrodolerite and dolerite showed that sulfide ore minerals in them were formed both by hydrothermal and magmatic processes. The analysis of melt inclusions demonstrated that magmatic complexes formed from a high-temperature (1210–1255°C) low-potassium melt of the N-MORB type. Investigations of fluid inclusions revealed that gabbro and dolerite formed under the influence of an active hydrothermal system at a temperature of 205–226°C. Thus, the Sierra Leone Fracture Zone is considered to be perspective for the discovery of a new hydrothermal field.     

Magnetic fields and the abundance of iron at the surface of late-type dwarfs

A program package developed for implementation of the Stenflo-Lindegren method for investigation of magnetic fields with complex structure is described. It has been used to carry out magnetic field diagnostics of several G-K dwarfs. A field the order of 1 kG was detected at the surface of two of them — Eri and 61 Cyg A. The magnetic field determination for Eri is compared with previously published results. An interactive PC program developed for measurement of equivalent widths of spectral lines by various methods is also described. It was used to determine the iron abundance in the atmospheres of the stars under investigation. Comparison with data from the [Fe/H] catalog of Carel de Strobel [14] indicates that our values are higher by 0.2 dex for Eri and Boo A.Translated fromAstrofizika, Vol. 39, No. 1, pp. 5–18, January–March, 1996.