Simulation of Microwave Emission from the Magnetic Arch with Growing Millimeter Spectrum

A three-dimensional simulation of the microwave emission of nonthermal electrons within a flare magnetic loop that takes into account the influence of the chromosphere has been carried out. The paper investigates the possibility of the generation of a microwave spectrum (observed for some solar flares) with a maximum in the centimeter wavelength range and a positive slope in the millimeter one under the some distribution of the magnetic field strength and the parameters of the anisotropic nonthermal electrons along the loop. By the example of the event on July 5, 2012, it is shown that nonthermal electrons can be responsible not only for the centimeter bell-shaped emission spectrum generated in the coronal part of the loop but also for the increasing millimeter spectrum generated in the chromosphere.     

An Abnormal Isotopic Composition of Oxygen in Zircon from Corundum-Bearing Metasomatites of the Dyadina Gora Ore Occurrence,Belomorian Mobile Belt

Doklady Earth Sciences - For the first time, the isotopic composition of oxygen, the content of trace elements, and the U–Pb zircon age were determined for kyanite–gedrite metasomatites...     

First Data on the Age (U–Pb,SHRIMP-II) and Composition of Zircon from the Unique Yarega Oil–Titanium Deposit,South Timan

Doklady Earth Sciences - Isotope–geochemical study of zircon from leucoxene–quartz sandstone of the Yarega deposit in South Timan was conducted for the first time using the Sensitive...     

Epigenetic Alteration of Cupreous Gold in the Au–Ag–Cu–Pd Exsolution Texture

Doklady Earth Sciences - The exsolution texture of the Au–Ag–Cu–Pt solid solution is represented by numerous lamellae of cupreous gold in the Ag–Au–Pd matrix. On...     

Optical observations of gamma-ray bursts, the discovery of supernovae 2005bv, 2005ee, and 2006ak, and searches for transients using the “MASTER” robotic telescope

We present the results of observations obtained using the MASTER robotic telescope in 2005–2006, including the earliest observations of the optical emission of the gamma-ray bursts GRB 050824 and GRB 060926. Together with later observations, these data yield the brightness-variation law t ^?0.55±0.05 for GRB 050824. An optical flare was detected in GRB 060926—a brightness enhancement that repeated the behavior observed in the X-ray variations. The spectrum of GRB 060926 is found to be F _E ～ E ^?β , where β = 1.0 ± 0.2. Limits on the optical brightnesses of 26 gamma-ray bursts have been derived, 9 of these for the first time. Data for more than 90% of the accessible sky down to 19 ^m were taken and reduced in real time during the survey. A database has been composed based on these data. Limits have been placed on the rate of optical flares that are not associated with detected gamma-ray bursts, and on the opening angle for the beams of gamma-ray bursts. Three new supernovae have been discovered: SN 2005bv (type Ia)—the first to be discovered on Russian territory, SN 2005ee—one of the most powerful type II supernovae known, and SN 2006ak (type Ia). We have obtained an image of SN 2006X during the growth stage and a light curve that fully describes the brightness maximum and exponential decay. A new method for searching for optical transients of gamma-ray bursts detected using triangulation from various spacecraft is proposed and tested.     

Thermal expansion of ZnSiO<Subscript>3</Subscript> high-pressure phases

Thermal expansion of ZnSiO₃ high-pressure clinopyroxene and ilmenite phases was measured in the temperature range 100–620 K by the X-ray powder diffraction method. Interpolation and extrapolation of experimental data were performed by the procedure based on the Debye-Mie-Gruneisen theory in the range from 50 to 1,500 K. Temperature dependencies of molar volumes and coefficients of bulk thermal expansion of ZnSiO₃ phases were determined.