Soft gamma repeaters outside the Local Group

We propose that the best sites to search for soft gamma repeaters (SGRs) outside the Local Group are galaxies with active massive-star formation. Different possibilities to observe SGR activity from these sites are discussed. In particular, we have searched for giant flares from the nearby galaxies (∼2–4 Mpc away) M82, M83, NGC 253 and 4945 in the Burst and Transient Source Experiment (BATSE) data. No candidate giant SGR flares were found. The absence of such detections implies that the rate of giant flares with energy release in the initial spike above  0.5 × 10⁴⁴ erg  is less than 1/30 yr⁻¹ in our Galaxy. However, hyperflares similar to that of 2004 December 27 can be observed from larger distances. Nevertheless, we do not see any significant excess of short GRBs from the Virgo galaxy cluster or from the galaxies Arp 299 and NGC 3256 (both with extremely high star formation rates). This implies that the Galactic rate of hyperflares with energy release  ∼10⁴⁶ erg  is less than ∼10⁻³ yr⁻¹. With this constraint the fraction of possible extragalactic SGR hyperflares among BATSE's short GRBs should not exceed a few per cent. We present the list of short GRBs coincident with the galaxies mentioned above, and discuss the possibility that some of them are SGR giant flares. We propose that the best target for the observations of extragalactic SGR flares with Swift is the Virgo cluster.     

A comparison of the magnetic field anomalies for the moon and earth

A comparative analysis of the anomalous magnetic field of the Moon, information about which was obtained by the Apollo 15 subsatellite, and the anomalous magnetic field of the Earth, involving data provided from surveys at various altitudes (up to 500 km) is given. As a result of spectral analysis of these fields it is shown that the main difference of the spectra is in the lower intensity of long period lunar anomalies and the increased rate of their damping with height, which is probably connected with the absence of any kind of magnetization by induction.     

Chronological and genetic relationships between intrusive rocks of the Berdyaush pluton,South Urals,in light of new U-Pb and Sm-Nd isotopic data

Geological observations in combination with previously published and new isotopic data allowed us to reconstruct the history of geological events that eventually gave rise to the formation of the Berdyaush pluton situated on the western slope of the South Urals: (1) emplacement of gabbro into Lower Riphean sedimentary rocks (1410–1390 Ma); an enriched mantle source of gabbro arising in the Archean or Paleoproterozoic; (2) formation of granitic melt in the lower crust; Archean TTG association subsequently enriched in K and correlative elements as a result of interaction with enriched mantle-derived magmas and related fluids was a magma source; mixing of mantle and crustal magmas in the course of their synchronous ascent with formation of hybrid intrusive rocks; injections of mafic and hybrid melts into incompletely solidified granite; fragmentation of such injections with the formation of melanocratic nodules; emplacement of basic dikes into the cooled granite—all these events took place 1410–1360 Ma ago; (3) discrete episodes of partial melting of enriched mantle source with waning intensity; formation of minor volumes of melt, which solidified under auto- and paraautochthonous conditions as local domains highly enriched in incompatible elements (1360–1270 Ma); (4) partial melting of those domains resulting in the formation of minor nepheline syenite intrusions (915–800 Ma), containing relict zircon grains dated at >1270 Ma; (5) injections of mantle-derived alkaline melt contaminated with crustal granitic material as microsyenite and syenite porphyry dikes (700–500 Ma ?). Thus, the Berdyaush pluton is a projection of a local domain of mantle and crustal magma generation, which periodically resumed its activity over almost a billion years.     

Hydrological Studies of Lake Outbursts in the Antarctic Oases

The results of a detailed hydrological study of the Larsemann Hills Oases (East Antarctica) during field seasons of 2017 to 2019 are presented. The study investigates a variety of lakes’ hydrological regime and the characteristics of outburst floods resulting from the lakes’ water flowing through tunnels in the snow-ice dams. The hydrographs calculated by the mathematical modeling do not generally contradict the physical essence of the process of outburst flood formation.

     

Astrokit-an efficient program for high-precision differential CCD photometry and search for variable stars

Having a need to perform differential photometry for tens of thousands stars in a several square degrees field, we developed Astrokit program. The software corrects the star brightness variations caused by variations of atmospheric transparency: to this end, the program selects for each star an individual ensemble of reference stars having similar magnitudes and positions in the frame. With ten or more reference stars in the ensemble, the differences between their spectral types and the spectral type of the object studied become unimportant. A strokit searches for variable stars using Robust Median Statistics criterion, which allows candidate variables to be selected more efficiently than by analyzing the standard deviation of star magnitudes. The software allows very precise automatic analysis of long inhomogeneous sets of photometric observations of a large number of objects to be performed, making it possible to find “hot Jupiter” type exoplanet transits and low-amplitude variables. We describe the algorithm of the program and the results of its application to reduce the data of the photometric sky survey in Cygnus as well as observations of the open cluster NGC188 and the transit of the exoplanet WASP-11 b /HAT-P-10 b, performed with the MASTER-II-URAL telescope of the Kourovka Astronomical Observatory of the Ural Federal University.     

First observations with the 64-m Kalyazin telescope included in a ground-based—space interferometer: The quasar 3C 147

The 64-m radio telescope equipped with an S-2 recording system in the town of Kalyazin was involved in an international fine-structure survey of quasars and active galactic nuclei carried out with a ground-based—space radio interferometer. The HALCA Japanese satellite in an orbit with an altitude of up to 24 000 km with an 8-m antenna was used as a space element of the interferometer. A radio image of the inner region of the CSS-type quasar 3C 147 was obtained with an angular resolution of ～0.3 mas at 6 cm. The image exhibits a core and several jet components mostly arranged in the main jet direction, but one of the components moves across the jet. No evidence was found for the superluminal separation of jet components. The estimated brightness temperature,～10¹¹ K, is consistent with the theoretical limit imposed by synchro-Compton radiation.     

The study of scattering effects by VLBI observations of PSR 0329+54 with HALCA at 1650 MHz

PSR0329+54 was observed at 1.6GHz with a space-ground radio interferometer with HALCA as a space radio telescope. The initial results of data processing are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Spectrum Power of Interstellar Plasma Inhomogeneities in the Direction of Eleven Radio Pulsars

Astronomy Reports - We have analyzed two-dimensional correlation functions from the dynamic spectra of 11 pulsars using the archival data of the “Radioastron” project. The time-sections...     

Nature and Age of Detrital Zircons from Rocks of the Shear Zone: The Problem of Occurrence of the Archean Basement in the Transangarian Yenisei Ridge

Petrogeochemical and geochronological study of boudined quartzite sandstones and tonalites, as well as host amphibolites, in the shear zone showed that potential sources of detrital zircons were Neoarchean–Paleoproterozoic rocks of the Angara–Kan block and products of their metamorphism. Interpretation of the available data does not confirm the inferred presence of the Early Precambrian basement of the Siberian Craton in the Transangara region.