How can α 2-dynamos generate axisymmetric magnetic fields?

Inspired by a recently observed axisymmetric field in a fully convective star we investigate the influence of an anisotropic diffusivity on the dynamo. We find that with reasonable assumptions for the anisotropy of the diffusivity and the α -effect the preference of axisymmetric modes is achieved. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68R_Earth) and Kepler-10b (∼1.416R_Earth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a “Hot Neptune” nor a “Hot Uranus”-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects.     

The Intensity–Velocity Phase Spectra of Evanescent Oscillations and Acoustic Sources

There are three major issues in modeling solar evanescent oscillations: the variation of the intensity [I]–velocity [V] phase difference of p-modes close to the base of photosphere; the existence of a plateau of negative I–V phase differences below and between the ridges of the low-frequency p-modes; the explanation of the I–V cross-spectra of the evanescent oscillations. We present new interpretations for the first two issues, based on modeling intensity fluctuations taking steep temperature gradients, opacity, and non-adiabatic cooling into account. We also discuss consequences of our model for the explanation of power spectra and cross-power spectra of p-modes. In particular, we present evidence that the acoustic sources that generate evanescent waves produce a coherent background that explains the plateau–interridge regime of negative I–V phase difference.     

Underwater camera system for deep‐sea bottom photography

A 35 mm camera system has been developed to operate to depths of 4,000 m. The system takes up to 24 pictures at one lowering, and uses standard torch batteries which last more than 10 lowerings.     

Determining Both Tropospheric and Stratospheric СО2 Contents Using a Ground-Based IR Spectroscopic Method

Izvestiya, Atmospheric and Oceanic Physics - Results obtained from ground-based high spectral resolution measurements of solar IR radiation absorption spectra are analyzed. These measurements have...     

Lithospheric Magnetic Anomalies of the Eastern Part of the Arctic Ocean as Images of Tectonic Structures

Izvestiya, Atmospheric and Oceanic Physics - Geomagnetic data measured by the CHAMP satellite have been used to construct the spatial distribution of the lithospheric magnetic anomaly field in the...     

Microseismicity in Local Areas: The Southeastern Part of the Fennoscandian Shield

This paper summarizes the observations of microseismic emissions by these authors in several areas of the Russian part of the Fennoscandian Shield to assess the potential of microseismicity to determine the present-day activity of local features in the upper part of the geologic medium. We give amplitude–frequency characteristics and the space–time distribution of naturally occurring microseismic events that are hypothesized to be of endogenous origin. We discuss the relationships these characteristics have to the regional geodynamic setting, average dimensions, and petrographic composition of active rock blocks.