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891.
We analyze the structure of the cluster of galaxies Abell 1775 (α = 13 h 42 m , δ = +26°22′, cz ≈ 21000 km/s), which exhibits a bimodal distribution of radial velocities of the containing galaxies. The difference of the subcluster radial velocities is ΔV ≈ 2900 km/s. We use the results of our photometric observations made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the spectroscopic and photometric data from the SDSS DR6 catalog to determine independent distances to the subclusters via three different methods: the Kormendy relation, photometric plane, and fundamental plane. We find that the A1775 cluster consists of two independent clusters, A1775A (cz = 19664 km/s) and A1775B (cz = 22576 km/s), each located at its own Hubble distance and having small peculiar velocities. Given the velocity dispersions of 324 km/s and 581 km/s and the dynamic masses within the R 200 radius equal to 0.6 × 1014 and 3.3 × 1014 M ⊙, the A1775A and A1775B clusters have the K-band luminosity-to-mass ratios of 29 and 61, respectively. A radio galaxy with an extended tail belongs to the A1775B cluster. 相似文献
892.
Using NSO/Kitt Peak synoptic charts from 1975 to 2003, we group the main solar magnetic fields into two categories: one for
active regions (ARs) and the other for extended bipolar regions (EBRs). Comparing them, we find that there exist three typical
characteristics in the variability of EBRs: First, there exists a correlation between ARs and EBRs. The phase of EBR flux
has a delay nearly two CRs. Second, we find that the EBR flux has two prominent periods at 1.79 years and 3.21 years. The
1.79-year period seems to only belong to large-scale magnetic features. Lastly, the North – South asymmetry of EBR flux is
not very significant on a time scale of one solar cycle. However, during solar maxima, its dominance is found to shift from
one hemisphere to the other. 相似文献
893.
E. V. Khrutskaya T. P. Kiseleva I. S. Izmailov M. Yu. Khovrichev A. A. Berezhnoy 《Solar System Research》2009,43(4):285-290
The results of astrometric observations of Saturn’s satellites (S1–S8) obtained using a 26-inch refractor and a normal astrograph at Pulkovo Observatory in 2004–2007 are given. High-accuracy equatorial coordinates of Saturn’s satellites in the system of the UCAC2 reference catalog and the relative “satellite-satellite” positions suitable for specifying their motion theories are obtained. The observations are compared with the DE405 + TASS1.7 and INPOP06 + TASS1.7 theories of motion. The root-mean-square errors of the obtained satellite positions lie within the range of 10–50 mas, as far as the intrinsic convergence is concerned, and 20–70 mas, as far as the extrinsic one is concerned. The observation results are included into the astrometrical database of the Pulkovo Observatory (www.puldb.ru). 相似文献
894.
C. LANA C. R. SOUZA FILHO Y. R. MARANGONI E. YOKOYAMA R. I. F. TRINDADE E. TOHVER W. U. REIMOLD 《Meteoritics & planetary science》2008,43(4):701-716
Abstract— The 40 km wide Araguainha structure in central Brazil is a shallowly eroded impact crater that presents unique insights into the final stages of complex crater formation. The dominant structural features preserved at Araguainha relate directly to the centripetal movement of the target rocks during the collapse of the transient cavity. Slumping of the transient cavity walls resulted in inward‐verging inclined folds and a km‐scale anticline in the outer ring of the structure. The folding stage was followed by radial and concentric faulting, with downward displacement of kilometer‐scale blocks around the crater rim. The central uplift records evidence for km‐scale upward movement of crystalline basement rocks from the transient cavity floor, and lateral moment of sedimentary target rocks detached from the cavity walls. Much of the structural grain in the central uplift relates to structural stacking of km‐scale thrust sheets of sedimentary strata onto the core of crystalline basement rocks. Outward‐plunging radial folds indicate tangential oblate shortening of the strata during the imbrication of the thrust sheets. Each individual sheet records an early stage of folding and thickening due to non‐coaxial strains, shortly before sheet imbrication. We attribute this folding and thickening phase to the kilometer‐scale inward movement of the target strata from the transient cavity walls to the central uplift. The outer parts of the central uplift record additional outward movement of the target rocks, possibly related to the collapse of the central uplift. An inner ring structure at 10–12 km from the crater center marks the extent of the deformation related to the outward movement of the target rocks. 相似文献
895.
K. C. WELTEN C. ALDERLIESTEN K. VAN DER BORG L. LINDNER T. LOEKEN L. SCHULTZ 《Meteoritics & planetary science》1997,32(6):775-780
Abstract— We measured the concentrations of the cosmogenic radionuclides 10Be (half-life = 1.51 × 106 a), 26Al (7.05 × 105 a) and 36Cl (3.01 × 105 a) in Lewis Cliff (LEW) 86360, an L-chondrite from the Lewis Cliff stranding area, East Antarctica. In addition, the concentrations and isotopic compositions of He, Ne and Ar were measured. The combined results yield a terrestrial age of 2.35 ± 0.15 Ma. Only one other stony meteorite with a similar terrestrial age (~2 Ma) is known from the Allan Hills stranding area (ALH 88019), whereas all previously dated stony meteorites from Antarctica are younger than 1 Ma. We argue that LEW 86360 spent most of its terrestrial residence time deep inside the ice, near the base of the glacier, where ice flow rates are much lower than at the surface. The terrestrial ages of LEW 86360 and ALH 88019 are consistent with existing hypotheses concerning the stability and persistence of the East Antarctic ice sheet. 相似文献
896.
Churyumov K. I. Klesachonok V. V. Mussaev F. A. Bikmaev I. F. Galazutdinov G. H. 《Earth, Moon, and Planets》1997,78(1-3):105-110
We present the results of the preliminary study of the comet Hale-Bopp spectrum obtained April 17, 1997 by K. Churyumov and F. Mussayev with the help of the 1-meter Zeiss reflector and the echelle spectrometer (spectral resolutionλ/Δ λ ≈ 50000), CCD and the long slit, oriented along the radius-vector(“Sun-comet direction”). Energy distributions for three selected regions including the C3, C2 (0-0) and CN(Δ ν = 0) molecules emissions of the comet Hale-Bopp spectrum were built. The rotational lines of the CN(Δ ν = 0) band were identified. The nature of the high emission peak near λ 4020 Å in the C3 band is discussed. The presence of the cometary continuum of the nonsolar origin is assumed. 相似文献
897.
ISLA will be an astronomical observatory, operating at the upper limit of our planet Earth atmosphere, offering space like
observing conditions in most aspects. ISLA can be maintained easily, modified easily if necessary, always kept at the state
of the art and operated for very extended periods without polluting the stratosphere. ISLA is ideally suited to become the
first world space observatory as the observing conditions are very much space-like – diffraction limited angular resolution,
very low ambient temperature, remote control – however ISLA is easily accessible, telescopes and instruments can be continuously
improved and ISLA's costs corresponds only to those of ground-based modern astronomical installations like the ESO-VLT-, KECK-
and GEMINI-observatories. The cost of observing and experimenting on ISLA will be orders of magnitudes lower than those of
building and operating any space telescope, allowing the astronomers of developing nations to participate in the ISLA observatory
within their limited financial possibilities as competent and full partners. ISLA's 4-m and 2-m telescopes will operate diffraction
limited from 0.3 μm in the optical, over the infrared, far-infrared to the sub-mm spectral range. ISLA's individual telescopes
will permit imaging with 20 milli-arcsec spatial resolution in the optical, 5 times better than the Hubble Space Telescope.
ISLA's telescopes can be combined to form an interferometer with a maximum baseline of 250 m with nearly complete coverage
of the u,v plane. Interferometric resolution will be of the order of 20 micro-arcsec for the optical. ISLA will thus offer
spatial resolution comparable or better than the intercontinental VLBI radio interferometers. ISLA's telescope efficiency
will be many orders of magnitude better than comparable ground-based telescopes. The light collecting power of ISLA's interferometric
telescopes will be orders of magnitudes greater than the future space interferometers under discussion. ISLA, being an aviation
project and not a space project, can be realised in the typical time scale for the development of aviation: about 5 years.
ISLA's cost for the whole observatory, including its movable ground station etc. will be of the order of a typical medium
size ESA space mission. ISLA's lifetime will be in excess of many decades, as it can easily be maintained, modernised, repaired
and improved. ISLA will become the origin of a new astronomical international organisation with worldwide participation. ISLA's
telescopes will be of the greatest importance to all astronomical fields, as it will permit to study much fainter, much more
distant objects with microscopic spatial resolution in wavelength regions inaccessible from ground. ISLA's many telescopes
permit easily simultaneous observations at many wavelengths for rapidly varying objects, from continuously monitoring the
surfaces of the planets in our solar system, surfaces of close-by stars, nuclei of galaxies to QSO's.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
898.
M. Barbera A. Collura A. Dara M. Leone F.R. Powell S. Serio S. Varisco M.V. Zombeck 《Experimental Astronomy》1997,7(1):51-63
We report on UV/Visible transmission measurements of aluminum coated Lexan filters designed as UV blocking filters for soft x-ray detectors. Transmission of the filters in the 2300-8000 Å wavelength range is significantly higher than expected. It cannot be accounted for applying a simple slab model of the transmission and adopting material properties reported in the literature. We show that this is due to interference effects which are strongly dependent on the filter geometry, and to oxidation of exposed aluminum surfaces and/or chemical interaction with the plastic support. The results of this work have led to the redesign of the Advanced X-ray Astrophysics Facility High Resolution Camera UV blocking filters. 相似文献
899.
900.