Creation of a Global Selenocentric Coordinate Reference Frame     

Nefedyev  Yu. A.  Andreev  A. O.  Petrova  N. K.  Demina  N. Yu.  Zagidullin  A. A. 《Astronomy Reports》2018,62(12):1016-1020

A number of questions about the Moon remain to be answered, including fundamental questions related to the internal structure and origin of the Moon. Studies of the spin–orbital dynamics of the Moon and of selenodesy are required for the practical solution of a number of problems related to navigation on the Moon and in circumlunar space, with the aim of providing coordinate and time support for planned lunar space projects. This paper analyzes existing dynamic selenographic reference grids, considers methods for their development and creation, and describes the modern projects related to navigational support for lunar missions. This paper is based on a presentation made at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017).

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Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records     

Andrei A. Andreev  Elena Raschke  Boris K. Biskaborn  Stuart A. Vyse  Jeremy Courtin  Thomas Böhmer  Kathleen Stoof-Leichsenring  Stefan Kruse  Lyudmila A. Pestryakova  Ulrike Herzschuh 《Boreas: An International Journal of Quaternary Research》2021,50(3):652-670

This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra- and steppe-like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb-dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae ~16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared ~15.9 cal. ka BP, and became dominant after ~15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after ~13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum ~11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow-water habitats. Shrubby and graminoid tundra was dominant ~11.8–11.1 cal. ka BP, later Salix stands significantly decreased. The forest-tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between ~10.6 and 7 cal. ka BP. Vegetation became similar to the modern after ~7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others.  相似文献   

Diagnostics of small-scale details on asteroid’s surface from the fast spectrophotometry data     

B. E. Zhilyaev  M. V. Andreev  A. V. Sergeev  V. G. Godunova  G. Z. Butenko  V. K. Taradiy 《Kinematics and Physics of Celestial Bodies》2016,32(5):245-249

To study the mineralogical composition of an asteroid’s surface with a technique of colorimetry of small-scale details, we propose fast spectrophotometry with a low-resolution imaging spectrograph and a time resolution of a few minutes. In contrast to global tomography, our method allows only the features of small scale, as compared to the asteroid’s size, to be detected. As an example, the surface of asteroid 130 Elektra exhibits approximately 16 spots of different mineralogical composition; their sizes range from 13 to 30 km. Except for several cases, the absorption spectra of these features are typical of the olivine–pyroxene compounds. In principle, color characteristics of the spots in the UBVRI color system allow the mineralogical composition of the surface of a small celestial body to be identified.  相似文献   

Changes in the height of the active Karymskii Volcano, Kamchatka during the period 1971–2007     

V. I. Andreev  M. A. Magus’kin 《Journal of Volcanology and Seismology》2009,3(2):81-88

Systematic measurements of the height of the summit crater rim on the active Karymskii Volcano showed that the variation of that parameter has been greater during its last eruption, lasting, with short intermissions, from January 1, 1996 until now (October 2007) compared with the earlier eruptions. The periodic increases in the height of Karymskii Volcano were due to explosion discharges of unconsolidated pyroclastic material, with most of this falling on the volcano’s cone. The increased seismicity of Karymskii Volcano intensified the slope movement processes, resulting in a comparatively flat area forming periodically on the crater rim; during separate, not very long, periods the height of the volcanic cone was increasing in discrete steps and at a greater rate. The periodic decrease in the height of Karymskii Volcano is due to compaction of pyroclastic material and, to a much greater extent, after violent explosions which expand the crater by removing its nearsummit circumference. The other contributing factor consists in sagging of the magma column due to partial emptying of the peripheral magma chamber, which makes the internal crater slope steeper, hence causes cone collapse and the cone lower. These occurrences are generally similar to the processes of crater and caldera generation described by previous investigators for other volcanoes of the world.  相似文献   

Cosmological parameters and the large numbers of Eddington and Dirac     

A. Yu. Andreev  B. V. Komberg 《Astronomy Reports》2000,44(3):139-141

Cosmological large numbers are studied using dimensional analysis. Expressions linking cosmological parameters with fundamental constants of the microworld are proposed. The Zel’dovich formula for the cosmological constant is generalized, and a series of characteristic masses of the Universe is derived.  相似文献   

Methane in Water and Bottom Sediments of Lake Baikal     

Gar’kusha  D. N.  Fedorov  Yu. A.  Tambieva  N. S.  Andreev  Yu. A.  Mikhailenko  O. A. 《Water Resources》2019,46(5):726-737

Water Resources - The distribution of methane concentration measured in 2014 and 2015 in different parts of Lake Baikal has been analyzed. In the period of expedition studies, methane concentration...  相似文献   

Circulation of Waters in the Northwestern Part of the Bering Sea According to Satellite Data     

Andreev  A. G. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(9):963-969

Izvestiya, Atmospheric and Oceanic Physics - A study of water circulation in the northwestern part of the Bering Sea using AVISO satellite data on velocities of geostrophic currents from 2002 to...  相似文献   

Environmental conditions in northwestern Russia during MIS 5 inferred from the pollen stratigraphy in a sediment core from Lake Ladoga     

Andrei A. Andreev  Lyudmila S. Shumilovskikh  Larisa A. Savelieva  Raphael Gromig  Grigory B. Fedorov  Anna Ludikova  Bernd Wagner  Volker Wennrich  Dominik Brill  Martin Melles 《Boreas: An International Journal of Quaternary Research》2019,48(2):377-386

Lake Ladoga hosts preglacial sediments, although the Eurasian ice sheet overrode the area during the LGM. These sediments were first discovered by a seismic survey and are investigated using a 22.75‐m‐long core. Its upper 13.30 m comprise Holocene and Lateglacial sediments separated from the lower 11.45 m of preglacial sediments by a hiatus. They consist of highly terrigenous lacustrine sediments, which according to OSL dating, were deposited during an early stage of the last ice age (MIS 5). The palynological data allow a first reconstruction of the Early Weichselian environmental history for northwestern Russia. Birch and alder forests with broad‐leaved taxa dominated during MIS 5d (c. 118–113 ka), suggesting a climate more favourable than in the Holocene. A high content of well‐sorted sands and poorly preserved palynomorphs indicates a shallow‐water environment at least temporarily. More fine‐grained sediments and better preserved organic remains suggest deeper water environments at the core location during MIS 5c (c. 113–88 ka). Pine and spruce became dominant, while broad‐leaved taxa started to disappear, especially after c. 90 ka, pointing to a gradual climate cooling. An increase in open herb‐dominated habitats at the beginning of MIS 5b (c. 88–86 ka) reflects a colder and dryer climate. However, later (c. 86–82 ka) pine and spruce again became more common. Birch and alder forests dominated in the area c. 82–80 ka (beginning of MIS 5a). Although open treeless habitats also became more common at this time, a slight increase in hazel may point to somewhat warmer climate conditions coinciding with the beginning of MIS 5a. The studied sediments also contain numerous remains of freshwater algae and cysts of marine and brackish‐water dinoflagellates and acritarchs documenting that the present lake basin was part of a brackish‐water basin during the Early Weichselian, probably as a gulf of the Pre‐Baltic Sea.  相似文献   

Kimberlites of the Manchary pipe: a new kimberlite field in Central Yakutia     

A.P. Smelov  A.P. Andreev  Z.A. Altukhova  S.A. Babushkina  K.A. Bekrenev  A.I. Zaitsev  E.D. Izbekov  O.V. Koroleva  V.M. Mishnin  A.V. Okrugin  O.B. Oleinikov  A.A. Surnin 《Russian Geology and Geophysics》2010,51(1):121-126

This paper reports new petrographic and mineralogical data on the Manchary kimberlite pipe, which was discovered south of Yakutsk (Central Yakutia) in 2007–2008, 100 km. The pipe breaks through the Upper Cambrian carbonate deposits and is overlain by Jurassic terrigenous rock masses about 100 m thick. It is composed of greenish-gray kimberlite breccia with a serpentine-micaceous cement of massive structure. The porphyry texture of kimberlite is due to the presence of olivine, phlogopite, and picroilmenite phenocrysts. The SiO₂ and Al₂O₃ contents of the groundmass are indicative of typical noncontaminated kimberlites. The groundmass has a significant content of ore minerals: Fe- and Cr-spinels, perovskite, magnetite, and, less commonly, magnesian Cr-magnetite. Pyropes occur in kimberlites as sharp-edged fragments and show uneven distribution. Chemically, they belong to lherzolite, wehrlite, or nondiamondiferous dunite–harzburgite parageneses. Garnets corresponding to lherzolites of anomalous composition make up 8%; this is close to the garnet content of Middle Paleozoic kimberlites from the Yakutian kimberlite province. The pyropes from the new pipe are compositionally similar to those from diamond-poor Middle Paleozoic kimberlites in the north of the Yakutian diamondiferous province. Chemically, pyropes from the Manchary pipe and those from the modern alluvium of the Kengkeme and Chakyya Rivers differ substantially. Consequently, the rocks of the pipe could not be a source of pyropes for this alluvium. They probably occured from other sources. This fact along with numerous “pipelike” geophysical anomalies, suggest the existence of a new kimberlite field in Central Yakutia.  相似文献   

Weather peculiarities of the 2007–2008 cold season in the Northern Caspian Sea     

B. Yu. Boldyrev  A. N. Andreev  Yu. V. Dozortseva 《Russian Meteorology and Hydrology》2009,34(2):89-92

Weather patterns of the cold season in the studied region of the Caspian Sea are quite complicated; ice processes here represent an actual threat for hydrotechnical and other engineering constructions located both on the coast and the Northern Caspian Sea shelf, as well as for the navigation in the ice covered sea. Analysis of the materials obtained from the researches performed in November 2007–March 2008 showed that weather patterns of the 2007–2008 cold season in the Northern Caspian Sea formed under the influence of synoptic processes differed from the multiyear norm. The unusually high frequency of anticyclonic processes (especially, the Siberian anticyclone) defined the low monthly average air temperature in January that was 2–5°C below the climatologic norm over the entire Northern Caspian water area.  相似文献