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31.
A rare occurrence of a crater-filling clastogenic extrusive coherent kimberlite,Victor Northwest (Ontario,Canada) 总被引：1，自引：1，他引：0
Bram I. van Straaten M. G. Kopylova J. K. Russell B. H. Scott Smith 《Bulletin of Volcanology》2011,73(8):1047-1062
Kimberlite pipes can contain significant proportions of dark and dense kimberlite that have mostly been interpreted as intrusive
coherent (hypabyssal) in origin. This study reports a well-documented occurrence of a fresh intra-crater clastogenic extrusive
coherent kimberlite that is concluded to have formed as a result of lava fountaining. This paper focuses on a dark, dense,
competent, generally crystal-rich, massive kimberlite unit within the Victor Northwest kimberlite pipe (Ontario, Canada).
Using a comprehensive volcanological and petrographic analysis of all available drill cores, it is shown that this unit has
a fresh well-crystallised coherent groundmass and is extrusive and pyroclastic in origin. The proposed clastogenic coherent
extrusive origin is based on deposit morphology, gradational contacts to enveloping pyroclastic units, as well as the presence
of remnant pyroclast outlines and angular broken olivines. This paper, and an increasing number of other studies, suggest
that fragmental extrusive coherent kimberlite in intra-crater settings may be more common than previously thought. The emplacement
history and volcanology of these pipes need to be reconsidered based on the emerging importance of this particular kimberlite
facies. 相似文献
32.
T. B. Goldvarg Yu. T. Tsap Yu. G. Kopylova A. V. Stepanov 《Bulletin of the Crimean Astrophysical Observatory》2013,109(1):90-97
The fine structure of the time variations of microwave and hard X-ray emissions from the solar flare of November 5, 1992 was analyzed. On the basis of the wavelet analysis, pulsations of intensity with a period of about 6 s were revealed in both the data sets. The observed time delay between the coronal plasma emission measure maximum and the temperature maximum is consistent with the concept of chromospheric evaporation. The anticorrelation observed between the time profiles of the microwave and hard X-ray emissions and the nature of the time delays between the peaks are associated with the excitation of radial fast magneto-acoustic oscillations in the flare loop (a coronal trap). Consequences of the obtained results are discussed. 相似文献
33.
We investigated the properties of galaxy clusters in the region of the Hercules supercluster using observational data from the SDSS and 2MASS catalogs and the NED. We have selected 13 galaxy clusters with a total dynamical mass of 4.82 × 1015 M ⊙ in a 100 × 45 Mpc supercluster region in the plane of the sky (0.030 < z < 0.041). In addition, our sample includes eight clusters from the immediate neighborhoods of the superclusters and ten field clusters at the same z. The derived properties of the rich Hercules supercluster are shown in comparison with the data for the poor Leo supercluster. The main parameters of the virialized galaxy cluster regions in the near infrared (K s ) for the Hercules supercluster differ from those for the Leo supercluster: the number of galaxies and the total luminosity (to a limiting magnitude of ?21 · m 5) increase with cluster mass (L K,200 ∝ M 200 0.91±0.07 and N 200 ∝ M 200 0.94±0.07 ), but the dependences are steeper by 0.28 and 0.22. In the virialized cluster regions, the fraction of early-type galaxies selected by the bulge contribution, concentration index, and u t= r color is, on average, 66% (60% in Leo, 70% in the field) among the galaxies brighter than ?23 · m 3 and 54% (51% in Leo, 61% in the field) among the galaxies brighter than ?22 · m 3. The fraction of early-type galaxies in the superclusters does not change with galaxy cluster mass and luminosity. The composite luminosity function of the rich Hercules supercluster is described by a Schechter function and does not differ from the luminosity function of the poor Leo supercluster for the luminosity interval [?26 m , ?21 · m 5] but differs from the field luminosity function at the same z determined from ten galaxy clusters. 相似文献
34.
Y. T. Tsap Y. G. Kopylova A. V. Stepanov V. F. Melnikov K. Shibasaki 《Solar physics》2008,253(1-2):161-172
Within the framework of ideal magnetohydrodynamics the excitation of the ballooning instability in a toroidal coronal loop with a radius of cross section a and a radius of curvature R is analyzed by using the energy method. Kink oscillations are able to excite the ballooning instability when the plasma beta parameter β>2a/R. It has been suggested that this can result in the formation of cusp-shaped coronal loops. Modulation of gyrosynchrotron emission caused by kink oscillations is considered. The intensity of gyrosynchrotron emission for optically thin sources is the most sensitive to Alfvén disturbances. The obtained theoretical results are discussed in the light of Yohkoh, SOHO, TRACE, RHESSI, and Nobeyama observations. 相似文献
35.
We analyze the properties of the clusters of galaxies in the region of the Ursa Major (UMa) supercluster using observational data from SDSS and 2MASS catalogs. The region studied includes a supercluster (with a galaxy and cluster overdensity of 3 and 15, respectively) and field clusters inside the 150-Mpc diameter surrounding region. The total dynamical mass of 10 clusters of galaxies in UMa is equal to 2.25 × 1015 M ⊙, and the mass of 11 clusters of galaxies in the UMa neighborhood is equal to 1.70 × 1015 M ⊙. The fraction of early-type galaxies brighter than M K * + 1 in the virialized regions of clusters is, on the average, equal to 70%, and it is virtually independent on the mass of the cluster. The fraction of these galaxies and their average photometric parameters are almost the same both for UMa clusters and for the clusters located in its surroundings. Parameters of the clusters of galaxies, such as infrared luminosities up to a fixed magnitude, the mass-to-luminosity ratio, and the number of galaxies have almost the same correlations with the cluster mass as in other samples of galaxies clusters. However, the scatter of these parameters for UMa member clusters is twice smaller than the corresponding scatter for field clusters, possibly, due to the common origin of UMa clusters and synchronized dynamical evolution of clusters in the supercluster. 相似文献
36.
We study the A1831 cluster within the framework of our program of the investigation of galaxy clusters with bimodal velocity
distributions (i.e., clusters where the velocities of subsystems differ by more than Δ
cz
∼ 3000 km/s).We identify two subsystems in this cluster: A1831A (cz = 18970 km/s) and A1831B (cz = 22629 km/s) and directly estimate the distances to these subsystems using three methods applied to early-type galaxies:
the Kormendy relation, the photometric plane, and the fundamental plane. To this end, we use the results of our observations
made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the data adopted
from the SDSS DR6 catalog. We confirmed at a 99% confidence level that (1) the two subsystems are located at different distances,
which are close to their Hubble distances, and (2) the two subsystems are located behind one another along the line of sight
and are not gravitationally bound to each other. Both clusters have a complex internal structure, which makes it difficult
to determine their dynamical parameters. Our estimates for the velocity dispersions and masses of the two clusters: 480 km/s
and 1.9 × 1014
M
⊙ for A1831A, 952 km/s and 1.4 × 1015
M
⊙ for A1831B should be views as upper limits. At least three spatially and kinematically distinct groups of galaxies can be
identified in the foreground cluster A1831A, and this fact is indicative of its incomplete dynamical relaxation. Neither can
we rule out the possibility of a random projection. The estimate of the mass of the main cluster A1831B based on the dispersion
of the line-of-sight velocities of galaxies is two-to-three times greater than the independent mass estimates based on the
total K-band luminosity, temperature, and luminosity of the X-ray gas of the cluster. This fact, combined with the peculiarities
of its kinematical structure, leads us to conclude that the cluster is in a dynamically active state: galaxies and groups
of galaxies with large line-of-sight velocities relative to the center of the cluster accrete onto the virialized nucleus
of the cluster (possibly, along the filament directed close to the line of sight). 相似文献
37.
Tsap Yu. T. Stepanov A. V. Kopylova Yu. G. Akhtemov Z. S. Malashchuk V. M. 《Geomagnetism and Aeronomy》2020,60(8):1067-1070
Geomagnetism and Aeronomy - The possibility that large-scale coronal loops of solar-type stars and M dwarfs make a significant contribution to the white-light continuum emission is considered. It... 相似文献
38.
We analyze the properties of galaxy clusters in the region of the Leo supercluster using observational data from the SDSS
and 2MASS catalogs. We have selected 14 galaxy clusters with a total dynamical mass of 1.77 × 1015
M
⊙ in the supercluster region 130 by 60 Mpc in the plane of the sky (z ≃ 0.037). The composite luminosity function of the supercluster is described by a Schechter function with parameters that,
within the error limits, correspond to field galaxies and does not differ from the luminosity function of the richer Ursa
Major (UMa) supercluster for the same luminosity range (the bright end). The luminosity functions of early-type and late-type
galaxies in Leo at the faint end are characterized by a sharp decrease (α = −0.60±0.08) and a steep increase (α = −1.44± 0.10) in the number of galaxies, respectively. In the virialized cluster regions, the fraction of early-type galaxies
selected by the u-r color, bulge contribution, and concentration index among the galaxies brighter than M
K
* + 1 is, on average, 62%. This fraction is smaller than that in the UMa supercluster at a 2–3σ level. The near-infrared luminosities of galaxy clusters down to a fixed absolute magnitude correlate with their masses almost
in the same way as for other samples of galaxy clusters (L
200,K
∝ M
2000.63±0.11)). 相似文献
39.
The influence of collisions between neutrals and ions on the energy flux of Alfvén-type waves in partially ionized plasma
based on the three-fluid equations is considered. It has been shown that amplitudes of Alfvén waves that are generated or
propagating in the solar photosphere do not depend on the ionization ratio, if the wave periods are much larger than 10−4 s. This contradicts results of Vranjes et al. (Astron. Astrophys.
478, 553, 2008) and is explained by the strong coupling due to ion–neutral collisions. Alfvén waves can be effectively excited in the photosphere
of the Sun by convective motions, providing the required energy for coronal heating. 相似文献
40.
Vanished diamondiferous cratonic root beneath the Southern Superior province: evidence from diamond inclusions in the Wawa metaconglomerate 总被引：2，自引：1，他引：1
Christine E. Miller Maya G. Kopylova John Ryder 《Contributions to Mineralogy and Petrology》2012,164(4):697-714
We studied diamonds from a 2.697–2.700 Ga Wawa metaconglomerate (Southern Superior craton) and identified mineral inclusions of high-Cr, low-Ca pyrope garnet, low-Ti Mg-chromite, olivine (Fo93), and orthopyroxene (En94). The diamonds have δ13C of ?2.5 to ?4.0 ‰ and derive from the spinel-garnet and garnet facia of harzburgite. Geothermobarometry on non-touching, coexisting garnet-olivine and garnet-orthopyroxene pairs constrains the maximum geothermal gradient of 41 mW/m2 for the Neoarchean and a minimum lithosphere thickness of 190 km. The depleted harzburgitic paragenesis equilibrated at a relatively cold geotherm suggests the presence of a pre-2.7 Ga diamondiferous cratonic root beneath the northern Wawa terrane or the Opatica terrane of the Southern Superior craton, i.e., beneath terranes identified as sources for the metaconglomerate diamonds. Geophysical surveys, geothermal data, and petrology of mantle xenoliths emplaced in the Proterozoic-Mesozoic trace evolution of the mantle thermal regime and composition from the Archean to present. The root was thinned down to 150 km by the Jurassic, when the mantle was heated to 41–42 mW/m2. The diamondiferous root destruction was accompanied by more significant heating and was complete by 1.1 Ga in areas adjacent to the Midcontinent Rift. The geometry of the current high-velocity root and spatial correlations with boundaries of crustal terranes that docked to the nuclei of the Superior protocraton in the Neoarchean suggest that the root destruction in the Southern Superior may have been associated with tectonic erosion, craton amalgamation, and ensuing ingress of asthenospheric fluids. 相似文献