共查询到20条相似文献，搜索用时 949 毫秒
1.
T.Kiang 《中国天文和天体物理学报》2003,3(2):95-104
A new way of probing the harge-scale structure of the universe is proposed.Space is partitioned into cells the shape of rhombic dodecahedron.The cells are labelled “filled“ or “empty“ according as they contain galaxies or not ,the cell size is so chosen as to have narly equal numbers of filled and empty cells for the given galaxy sample.Two observables on each cell are definable:the number of ist like neighbors,n1,and a two-suffixed topological type τ,the suffixes being the numbers of its like and unlike neighbor-groups.The frequency distributions of n1 and τ in the observed set of filled(empty)cells are then considered as indicators of the morphology of the set,The method is applied to the CfA catalogue of galaxies as an illustration.Despite its limited size,the data offers evidence 1) that the empty cells are more stongly clustered than the filled cells,and 2) theat the filled cells,but not the empty cells,have a tendency to occur in sheets,Further directions of development both in theory and application are indicated. 相似文献
2.
J. B. Ohanesyan 《Astrophysics》2008,51(4):490-505
The dependence of the equivalent widths of the 2786–2810 Å spectral band and the MgII 4481 Å line on the basic parameters
(Teff, logg and [M/H]) for 137 bright A-stars shows that 60 of them are candidate peculiar stars. Given the similar behavior of
W(2800) and W(4481), it can be assumed that 34 of the stars are chemically peculiar stars. The anomalous values of W(2800),
W(4481), and [M/H] vary over wide limits for the rest of the stars, possibly because they are binary.
Translated from Astrofizika, Vol. 51, No. 4, pp. 577–593 (November 2008). 相似文献
3.
D. A. Rastegaev Yu. Yu. Balega V. V. Dyachenko A. F. Maksimov E. V. Malogolovets 《Astrophysical Bulletin》2014,69(3):296-304
We present the results of speckle interferometric observations of 156 stars possessing global magnetic fields, carried out with the 6-m BTA telescope of the Special Astrophysical Observatory. Virtually all stars were observed between 2010 and 2012. Thirty-four stars were resolved into individual components (31 double and 3 triple), of which 14 binary systems (BD+41○43, HD2887, HD30466, HD36540, HD36955, HD37479, HD61045, HD89069, HD144334, HD164258, HD349321, HD343872, HD184471, HD196691) and 2 triple systems (HD37140, HD338226) were for the first time resolved by the astrometric method. 相似文献
4.
Jian-ZhongLiu Yong-Liao Zou Chun-Lai Li Lin Xu Zi-Yuan OuyangNational Astronomical Observatories Chinese Academy of Sciences Beijing jzliu@bao. ac. cnInstitute of Geochemistry Chinese Academy of Sciences Guiyang 《中国天文和天体物理学报》2004,4(2)
The Antarctic Continent has become the largest natural preservatory of meteorites in the world because of its unique geographical position and climatic conditions. Mt. Grove is located in the inland area of the Antarctic Continent where the conditions are favorable for the preservation of meteorites. During China's 15th, 16th and 19th Antarctic Scientific Explorations a large number of meteorites were recovered in the Mt. Grove region. Especially during the 19th Exploration in 2002/03 a total of 4448 meteorites were recovered, which at one stroke put China among countries that have recovered most numbers of meteorites. Here, we report mainly the results of microscope and electron microprobe studies of 28 meteorites recovered during the 16th Exploration. The meteorites are chemically classified based on their mean Fa contents of olivine, mean Fs contents of low-Ca pyroxene and abundances of Fe-Ni metal. We also give a brief account of the meteorite recovery during the three Explorations and of some preli 相似文献
5.
Jia-Long Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,(3)
Taking the 13-point smoothed monthly sunspot number, Ri, and the deviation of the 13 associated monthly sunspot numbers from the smoothed one, D_i, as a number-pair describing the global level of sunspot activity, the evolution of the level is statistically studied for the period from the month which is just 48 months before the minimum to the minimum in the descending phase, using the observed data of Solar Cycles 10 to 22. Our results show (1) for 46 months (94%) of the studied 49 months it is found that for a given month, the distribution of the 13 pairs which come from the 13 solar cycles on a log Ri-D_i plane may be fitted by a straight line with a correlation coefficient larger than the critical one at confidence level α= 5%, and for 36 months (73%) the fitting is even better, for α= 1%;(2) time variations of these two parameters and their correlations in the studied period can be described respectively by functions of time, whose main trends may be expressed by a linear or simple curvilinear function; (3) the evolutionary path of the level of sunspot activity may be represented by a logarithmic function as log R_i=0.704 In D_i-0.291. 相似文献
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The results of spectroscopic observations of 28 galaxies of the Second Byurakan Sky Survey, completing the follow-up spectroscopy of galaxies in the survey field with central coordinates = 12h22m, = +35°, are presented. The spectra were obtained on the 2.6 m telescope of the Byurakan Astrophysical Observatory, National Academy of Sciences of the Republic of Armenia, and the 6 m telescope of the Special Astrophysical Observatory, Russian Academy of Sciences. The redshifts and absolute stellar magnitudes of all the galaxies have been determined. A preliminary analysis of the spatial distribution of all galaxies in this sample is given. 相似文献
8.
We consider the physical origin of the hemispheric pattern of filament chirality on the Sun. Our 3D simulations of the coronal
field evolution over a period of six months, based on photospheric magnetic measurements, were previously shown to be highly
successful at reproducing observed filament chiralities. In this paper we identify and describe the physical mechanisms responsible
for this success. The key mechanisms are found to be (1) differential rotation of north – south polarity inversion lines,
(2) the shape of bipolar active regions, and (3) evolution of skew over a period of many days. As on the real Sun, the hemispheric
pattern in our simulations holds in a statistical sense. Exceptions arise naturally for filaments in certain locations relative
to bipolar active regions or from interactions among a number of active regions. 相似文献
9.
Yu. N. Parijskij M. G. Mingaliev N. A. Nizhel’skii N. N. Bursov A. B. Berlin A. A. Grechkin V. I. Zharov G. V. Zhekanis E. K. Majorova T. A. Semenova V. A. Stolyarov P. G. Tsybulev D. V. Kratov R. Yu. Udovitskii V. B. Khaikin 《Astrophysical Bulletin》2011,66(4):424-435
The results of the first stage of the “Cosmological Gene” project of the Russian Academy of Sciences are reported. These results consist in the accumulation of multi-frequency data in 31 frequency channels in the wavelength interval 1–55 cm with maximum achievable statistical sensitivity limited by the noise of background radio sources at all wavelengths exceeding 1.38 cm. The survey region is determined by constraints 00 h < RA < 24 h and 40°30′ < DEC < 42°30′. The scientific goals of the project are refined in view of recent proposals to use cosmological background radiation data for the development of a unified physical theory. Experimental data obtained with the RATAN-600 radio telescope are used to refine the contribution of the main “screens” located between the observer and the formation epoch of cosmic background radiation (z = 1100). Experimental data for synchrotron radiation and free-free noise on scales that are of interest for the anisotropy of cosmic microwave background are reported as well as the contribution of these noise components in millimeter-wave experiments to be performed in the nearest years. The role of dipole radio emission of fullerene-type dust nanostructures is shown to be small. The most precise estimates of the role of background radio sources with inverted spectra are given and these sources are shown to create no serious interference in experiments. The average spectral indices of the weakest sources of the NVSS and FIRST catalogs are estimated. The “saturation” data for all wavelengths allowed a constraint to be imposed on the Sunyaev-Zeldovich noise (the SZ noise) at all wavelengths, and made it possible to obtain independent estimates of the average sky temperature from sources, substantially weaker than those listed in the NVSS catalog. These estimates are inconsistent with the existence of powerful extragalactic synchrotron background associated with radio sources. Appreciable “quadrupole” anisotropy in is detected in the distribution of the spectral index of the synchrotron radiation of the Galaxy, and this anisotropy should be taken into account when estimating the polarization of the cosmic microwave background on small l. All the results are compared to the results obtained by foreign researchers in recent years. 相似文献
10.
Bruce R. Bowman 《Celestial Mechanics and Dynamical Astronomy》1979,19(2):203-211
Analysis of high precision 2-day mean orbital elements of several U.S. Navy navigation satellites is presented. The combined analytical-numerical method for the computation of the elements from the Defense Mapping Agency precision ephemerides is described. The precision of the semimajor axis and the inclination orbital elements are determined to be 2 cm and 0.016 respectively. The 28th degree and 27th order terms of the geopotential field are determined with the mean elements. 相似文献
11.
The results of spectroscopic observations of 25 objects of the Second Byurakan Spectroscopic Sky Survey in a field with central coordinates a = 08h00m, δ = +59° are given. The spectra were obtained on the 2.6- m telescope of the Byurakan Astrophysical Observatory, National Academy of Sciences of the Republic of Armenia, and the 6- m telescope of the Special Astrophysical Observatory, Russian Academy of Sciences, in 1997– 1998 with a spectral resolution of from 5 to 15Å. The redshifts and absolute stellar magnitudes of all the galaxies were determined and they were classified. A histogram of the redshift distribution of the complete sample of galaxies in this field of the survey is given. 相似文献
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13.
D. Bewsher D. S. Brown C. J. Eyles B. J. Kellett G. J. White B. Swinyard 《Solar physics》2010,264(2):433-460
The aim of this paper is to calculate an accurate large-scale flatfield for the STEREO HI-1 instruments. This is done by analysing
the variation in intensity of stars in the background starfield as they pass across the CCD. In order to use the background
starfield, a photometric calibration is performed which defines a HI magnitude scale and a conversion between this scale and
measured intensity. The photometric calibration uses stellar spectra folded through the instrument response to make initial
intensity predictions. However, a secondary prediction method based on the photometric calibration, which blends the R-, V-
and B-magnitudes of a star, is derived for stars with no spectral information. 相似文献
14.
Dikpati and Choudhuri (1994, 1995) developed a model for the poleward migration of the weak diffuse magnetic field on the Sun's surface. This field was identified with the poloidal component produced by the solar dynamo operating at the base of the convection zone, and its evolution was studied by considering the effects of meridional circulation and turbulent diffusion. The earlier model is extended in this paper by incorporating the flux from, the decay of tilted active regions near the solar surface as an additional source of the poloidal field. This extended model can now explain various low-latitude features in the time-latitude diagram of the weak diffuse fields. These low-latitude features could not be accounted for in the earlier model, which was very successful in modeling the behavior at high latitudes. The time-latitude diagrams show that regions of a particular polarity often have tongues of opposite polarity. Such tongues can be produced in the theoretical model by incorporating fluctuations in the source term arising out of the decaying active regions. 相似文献
15.
Ground-based observations of the occultation of ? Gem by Mars on April 8, 1976 have been reduced in the manner of French et al. [Icarus 33, 186–202 (1978)] to yield the scale height and temperature profiles of the Martian atmosphere for number densities between 1013 and 1015 cm?3. The deduced variations in temperature are remarkably similar to those obtained by Elliot et al. [Astrophys. J.217, 661–679 (1977)] and to the in situ measurements from the Viking landers. 相似文献
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Spectra around the 6374 Å [Fex] and 7892 Å [Fexi] emission lines were obtained simultaneously with the 25-cm coronagraph at Norikura Observatory covering an area of 200 ×500 of the solar corona. The line width, peak intensity and line-of-sight velocity for both the lines were computed using Gaussian fits to the observed line profiles at each location (4 ×4 ) of the observed coronal region. The line-width measurements show that in steady coronal structures the FWHM of the 6374 Å emission line increases with height above the limb with an average value of 1.02 mÅ arc sec–1. The FWHM of the 7892 Å line also increases with height but at a smaller average value of 0.55 mÅ arc sec–1. These observations agree well with our earlier results obtained from observations of the red, green, and infrared emission lines that variation of the FWHM of the coronal emission lines with height in steady coronal structures depends on plasma temperatures they represent. The FWHM gradient is negative for high-temperature emission lines, positive for relatively low-temperature lines and smaller for emission lines in the intermediate temperature range. Such a behaviour in the variation of the FWHM of coronal emission lines with height above the limb suggests that it may not always be possible to interpret an increase in the FWHM of emission line with height as an increase in the nonthermal velocity, and hence rules out the existence of waves in steady coronal structures. 相似文献
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20.
Kinematics of local magnetic features (LMFs) have been investigated by analyzing a 22-year series of synoptic maps of the
radial magnetic field of the Sun (the term ‘local’ refers hereinafter to magnetic features with an effective size of the order
of an arc min). We applied the cross-correlation technique to analyse separately each of the harmonics obtained by using a
one-dimensional Fourier transform of the magnetic field in longitude. Such an approach allowed us to trace the motion of the
LMFs for a time interval as long as 12 Carrington rotations. The analysis also has shown that the effective size of the magnetic
tracers grows significantly with increasing age, which indicates that the local-scale magnetic features undergo diffusion-like
expansion and weakening, in agreement with Leighton's model of magnetic field evolution.
The LMFs emerging at latitudes between 10° and 55° reveal a poleward directed motion with a maximum velocity of about 14 m
s-1 near the latitude of 37°. The profile of the meridional velocity agrees approximately with that derived by Komm, Howard,
and Harvey (1993) for small-scale, short-lived magnetic features.
We have found that the LMFs rotate differentially at latitudes of up to 55°, and do not exhibit the ‘quasi-rigid’ rotation
that is assumed to be characteristic of long-lived magnetic features. This disagrees with the results obtained by Stenflo
(1989) and by Latushko (1994), who applied direct cross-correlation analysis of the synoptic maps. Such a discrepancy may
be treated as being a consequence of inhomogeneity of the large-scale solar magnetic field that consists of several components
with different kinematic characteristics. 相似文献