首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
We report preliminary results from a targeted investigation on quasars containing damped Lyman‐α absorption (DLA) lines as well strong metal absorption lines, carried out with the Potsdam Multi Aperture Spectrophotometer (PMAS). We search for line‐emitting objects at the same redshift as the absorption lines and close to the line of sight of the QSOs. We have observed and detected the already confirmed absorbing galaxies in Q2233+131 (zabs = 3.15) and Q0151+045 (zabs=0.168), while failing to find spectral signatures for the z = 0.091 absorber in Q0738+313. From the Q2233+131 DLA galaxy, we have detected extended Lyα emission from an area of 3″ ×5″. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
Parameters of the distant galaxy clusters of 3C295 (z=0.46) and Cl 0024+1654 (z=0.39) are compared with the predictions made using galaxies of the local clusters Coma (z=0.023) and DC 0329–52 (z=0.057) taking theK-effect into account. The distributions of colour and morphological type, and the amplitudesF +/F of the 0 4000 discontinuity are examined and no evidence for evolution of the galaxies and the clusters can be seen.  相似文献   

3.
To investigate the relationship between solar activity and the large-scale axisymmetric magnetic field of the Sun, we inferred from sunspot data over the period 1964–1985 a latitude–time distribution of magnetic field associated with active regions. This has been done allowing for both bipolar structure of the active regions and inclination of their axes to parallels of latitude, so the inferred magnetic field characterizes latitudinal separation of magnetic polarities which might be related to the large-scale magnetic field of the Sun according to the Babcock–Leighton model. The inferred magnetic field, A z, is compared with the longitude-averaged (zonal) magnetic field of the Sun, B z, derived from series of magnetograms obtained at Mount Wilson Observatory in the years 1964–1976, and at Kitt Peak National Observatory during the period from 1976 to 1985. The inferred magnetic field, A z, exhibits a complex structure distribution of magnetic polarities with respect to latitude and time. Apart from concentration of the different polarity magnetic fields inside the high- and low-latitude portions of the sunspot belts, bipolar active regions produce an intensive, shorter-scale component of the magnetic field which varies on the time scale of about 2 years. Such a short-term variation of A z reveals substantial correlation with the short-term component of B z which has the form of the poleward-drifting streams of magnetic field. Most significant correlation takes place between the short-term variations of A z occurring at latitudes below 20° and those of the large-scale magnetic fields occurring at middle latitudes of 40–50°. Moreover we analyze harmonic coefficients a l and b l obtained by expanding A z and B z into series in terms of the spherical harmonics. Power spectra of the time-dependent harmonic coefficients indicate that both A z and B z reveal a number of resonant modes which oscillate either with the 22-year period in the case of the anti-symmetric (odd-l) modes or with periods of about 2 years in the case of the symmetric (even-l) modes, but the resonant modes of A z have significantly larger values of the spherical harmonic degree l (and, hence, smaller spatial scales) as compared to those of B z. It is found that there is a close relationship between the harmonic coefficients b l and a m for which either ml16 (even l=4,...,10) or ml=4 (odd l=5,...,15).  相似文献   

4.
It is shown that the Hubble curvem(z) for galaxies and quasars averaged over a large volume of data forms in the first approximation a single continuous curve in the interval of red shifts 10–2.5z4.5, which is satisfactorily described by the dependence .A large deviation of the observed mean dependence from the theoretical one predicted by the standard cosmology is explained by the evolution of the galaxy and especially quasar luminosity. The corresponding mid-statistical function of the absolute luminosity variation for the last 4/5 times of existence in the Universe is equal toM(z)M(z 0)=logz/z 0+2z–0.4z 2.The luminosity of the most far distant from the observed quasars on the average by 5–6 stellar magnitudes high than the luminosity of near galaxies and quasars. It is obtained that even the most far distant quasars atz5 are in the maximum of luminosity, or their extinction has just began, thus the quasar formation should be expected forz>(5–6). The relative rate of the luminosity decrease of galaxies and near quasars is rather accurately amounts in the recent epoch 7% per 109 years. The obtained average Hubble curve of galaxies and quasars is evidently the main cause of their evolution in the Universe.  相似文献   

5.
In this paper I present a new evolution model of QSOs luminosity. The model is based on edges distribution of apparent magnitude-redshift of QSOs. After the quasars were formed, the luminosities were increasing until they attained their maximum value atz=2+a, where –0.1a0.6, then the luminosities were decreasing. If the QSOs originate from superconducting cosmic string of same initial massM i 1012 M , the formation epochs are different, most of the quasars start atz cutoff5.6. The most luminous QSOs start at later epochz cutoff5.15. The present sky survey echniques may give us the possibility to see the formation of QSOs at apparent magnitudem V 22.5 by chance of 0.3%.  相似文献   

6.
The colors of giant elliptical (gE) galaxies in clusters out to redshiftz=0.2, observed by Oke and Sandage (1968), are studied for systematic color-redshift effects. To reveal any intrinsic changes, theK term is subtracted from each color, after correction for galactic reddening and the resulting (B-V) c -K B-V versus z relation analysed. If the Oke and SandageK terms (relevant to nuclear colors) are used, the best fitting linear relation shows negligible change withz. But if the Whitford (1970)K terms (relevant to integrated colors) are used, there is a trend to bluer colors, by 0.07 mag.atz=0.2 if higher weight is given the better observed clusters. An upper limit, of ±0.08 mag. atz=0.2, is set to possible systematic aperture effects, by the total change between nuclear and integrated B-V and U-B of nearbygE galaxies.The color-redshift trends, interpreted as evolutionary changes, are related to evolution in the magnitude-redshift relation by means of models of stellar evolution in agE galaxy. If one uses the linear fit to the color-redshift relation obtained with WhitfordK terms and neglect of any aperture effects (which is the appropriate case if Oke and Sandage used large enough apertures), and if one adopts plausible limits to the ratio between color and magnitude evolution, the effect of evolution in the magnitude-redshift relation results in a negative value ofq 0. There are still substantial observational and theoretical uncertainties affecting this conclusion.  相似文献   

7.
The distribution of the absorption lines in the L forest of QSOs is re-examined in relation to both absorption and emission redshifts by analyzing a sample consisting of 20 QSO L forests.On the one hand, the -value in the relationN(z abs)=N 0(1+z abs) is re-estimated by applying the maximum likelihood (ML) method to all the L forests in our sample as a whole as well as to the forests for individual QSOs. The global estimated is 2.20±0.28 and both the quasars with highest and lowestz em do not individually have a significant effect on it. A non-parametric test on the estimate of from individual QSOs shows that there is no significant difference between the numbers of positive and negative -values. This does not, therefore, favour the idea that for individual QSOsN(z abs) decreases with increasingz abs.On the other hand, the possible correlation between the absorption line density and the emission redshift of the QSO itself, which was found by Bianet al. (1986, 1988) and re-discovered independently by Tytler (1987), is shown once again not only by the largerz em QSOs having larger mean density, but more importantly, at a rather high confidence level, by the fact that, at the same values ofz abs, QSOs with largerz em possess a greater number of L absorption lines.A discussion of the inverse effect suggests that it is still hard to say whether this effect really exists.  相似文献   

8.
In Table I we present seven digit numerical solutions of the Lane-Emden equation for the plane-parallel, cylindrical, and spherical case for polytropic indices ofn=–10, –5, –4, –3, –2, –1.5, –1.01, –0.9, –0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 10, 20, ±, supplemented byn=2.5, 3.5, 4.5, and 4.99 for the spherical case.In Table II some finite boundary values of polytropic slabs, cylinders, and spheres are summarized. For polytropic spheres (N=3) we have also quoted boundary values near the minimum of the dimensionless mass -2 11 occurring atn4.823 (Seidov and Kuzakhmedov, 1978).  相似文献   

9.
An object located approximately atl=8°,b=–4° with a mean radial velocity of –212.3 km s–1 has been observed in the 21 cm neutral hydrogen line. The mean weighted velocity dispersion is 11.2 km s–1 and the total mass is estimated to be 190R 2 (kpc) solar masses. We discuss possible interpretations of the origin and nature of this object. The most likely interpretation is that we observe an expanding object which has been ejected from the galactic nucleus.  相似文献   

10.
We compare families of simple periodic orbits of test particles in the Newtonian and relativistic problems of two fixed centers (black holes). The Newtonian problem is integrable, while the relativistic problem is highly non-integrable.The orbits are calculated on the meridian plane through the fixed centersM 1 (atz=+1) andM 2 (atz=–1) for energies smaller than the escape energyE=1. We use prolate spheroidal coordinates (, , =const) and also the variables =cosh and =–cos . The orbits are inside a curve of zero velocity (CZV). The Newtonian orbits are also limited by an ellipse and a hyperbola, or by two eillipses. There are 3 main types of periodic orbits (1) elliptic type (around both centers), (2) hyperbolic-type, and (3) resonant-type.The elliptic type orbits are stable in the Newtonian case and both stable and unstable in the relativistic case. From the stable orbits bifurcate double period orbits both symmetric and asymmetric with respect to thez-axis. There are also higher order bifurcations. The hyperbolic-type orbits are unstable. The Newtonian resonant orbits are defined by the ratiot µ/t =n/m of oscillations along and during one period, and they are all marginally unstable. The corresponding relativistic orbits are stable, or unstable. The main families are figure eight orbits aroundM 1, or aroundM 2 (3/1 orbits); gamma, or inverse gamma orbits (4/2); higher resonant families 5/1,7/1,...,8/2,12/2,...;, more complicated orbits, like 5/3, and bifurcations from the above orbits. Satellite orbits aroundM 1, orM 2, and their bifurcations (e.g. double period) exist in the relativistic case but not in the Newtonian case. The characteristics of the various families are quite different in the Newtonian and the relativistic cases. The sizes of the orbits and their stabilities are also quite different in general. In the Appendix we study the various types of straight line orbits and prove that some subcases introduced by Charlier (1902) are impossible.  相似文献   

11.
The chance that the pair of X-ray sources observed across NGC 4258 is accidental can be calculated as 5×10–6. The recent confirmation as quasars, and determination of the redshifts of the pair, atz=0.40 and 0.65 by E.M. Burbidge enables the final accidental probability of the configuration to be calculated as <4×10–7. In addition there are a number of observations which indicate the central Seyfert galaxy is ejecting material from its active nucleus.The NGC 4258 association is compared to four other examples of close association of pairs of X-ray quasars with low redshift galaxies. It is concluded that in each of these five cases the chance of accidental association is less than one in a million. The ejection speed calculated from the redshift differences of the X-ray quasars is 0.12c. This agrees with the ejection velocity of 0.1c calculated in 1968 from radio quasars associated with low redshift peaks become narrower—simultaneously strengthening the ejection origin for quasars and the quantization property of their redshift  相似文献   

12.
On the basis of empirical (D)-dependency at the frequency of 5 GHz constructed using 15 planetary nebulae with the independently measured distances (10–171×10–20 W m–2 Hz–1 ster–1), we evaluated distances of 335 objects. Independent evidence of the correctness of the accepted scale are given. Then(D)-dependency is constructed and it is shown that atD<0.08 pc the mean electron density is higher than the one determined by the Seaton method. We showed that the filling factor diminishes with the increase of the PN diameter (1 atD0.08 pc and 0.2 atD0.4 pc). the ionized mass of 33 PNs is determined. With the diameter increase the ionized mass grows and atD0.4 pc reaches the valueM0.07M . We used the new distance scale when investigating the space distribution of PNs. The mean scale height =130±15 pc and the mean gradient of the change of surface densitym=0.37, which allowed us to estimate the total number of nebulae in the GalaxyN4×104. We divided the PNs according to their velocities (withV LSR>35 km s–1 andV LSR<35 km s–1) and permitted us to confirm that the PN belong to different sub-systems of the Galaxy. The estimated local formation rate of PNs [=(4.6±2.2)×10–12 pc–3 yr–1] is a little higher than the one of the white dwarfs. That can be explained by a large number of PNs having binary cores, which used in our sample. The statistical estimation of PN expansion velocity showed thatV ex increases from 5–7 km s–1 (atD0.03 pc) to 40–50 km s–1 (atD0.8 pc).  相似文献   

13.
A gap in the distribution of a parameter is simply the absence of the parameter for the values corresponding to the gap. The gap in the emission line redshift (z) of QSOs thus represents absence of QSOs with emission line redshift values corresponding to the gap region. Gaps in emission line redshifts of QSOs have been analysed statistically with updated data consisting of 1549 values. The study indicates: (i) There is a critical redshiftz c =2.4, which separates two distinct phases in the creation of QSOs. Forz>z c , the creation appears to have been a slow process. Atz?z c there was a triggering action which produced a burst of QSOs simultaneously. Forz c , the rate of production of QSOs have been fast. (ii) The distribution of gaps atz c ; appear to be consequence of periodicities, provided the periodicities involved are perfect and the redshift values are accurate. (iii) The distribution of gaps atz>z c are not random, but follow a definite trend.  相似文献   

14.
The temperature profile of the KTB pilot drillhole, T(z)KTB-PH,is distinctly nonlinear: a temperature deficit ΔT (relative to a linear temperature-depth profile) is especially pronounced in the depth range 500–3500 m. The depth dependence of the deficit, Δ(z) is compared to be anticipated effect of surface paleoclimatic variations, ΔTpc(z), at the drillsite on the temperature profile. The latter can be calculated from available paleo-climatic models. If ΔTpc(z) is added to T(z)KTB-PH, a nearly linear temperature-depth curve results with an average geothermal gradient of 27.9°C/km. This, together with an average vertical thermal conductivity of 3.0 W/mK, estimated from KTB drillcore data, implies a heat flow density at the KTB site of 84 mW/m2. This modelled value is in good agreement with heat flow determinations in the adjacent Eger graben structure (Western Bohemian massif).  相似文献   

15.
A statistical analysis of the absorption line density N(zabs) in the forest of 16 high-redshift quasars shows that the line density is clearly dependent on the emission redshift of the quasar, zem. Not only is the mean density of all the absorption lines larger for larger zem, but more importantly, for each given absorption redshift interval, N(zabs) is also positively correlated with zem. A two-factor variance analysis, with ejection velocity as the second factor, shows that the line density in the forest depends sensitively on zem but not on the ejection velocity. These results are difficult to interpret by either the intervening or the ejecting hypothesis and are unlikely to be due to the selection effects suggested by Carswell et al. [13].  相似文献   

16.
The radial nonlinear pulsations of a model withM=0.8M ,M bol=–6 mag andT eff=5500 K have been studied. The pulsations are shown to exist in the form of the standing wave only in the innermost layers withR<0.2R ph. In the outer layers, the standing wave transforms into running waves, the frequency of which decreases with an increasingR. the pulsation period at the photosphere is found to be twice as long as the pulsation period atR<0.2R ph. The difference between the pulsation periods causes alternation of deep and shallow minima in the temporal dependences of the kinetic energy and radii and can be used to explain the nature of RV Tau variables. It is shown that at the distanceR>3R ph, the time-independent mass flux caused by shocks takes place. The rate of mass loss is found to beM10–4 M yr–1.  相似文献   

17.
The distribution of monthly counts of grouped solar flares N f has been studied for the time period 1967–1985 and they have been compared to other solar activity index R z , F 2800, and F 3750 i.e. intensities of solar radio flux at 2800 MH z and 3750 MH z . Seasonal variations have been found in the monthly distribution of solar flares.We have also studied the variation of the correlation coefficient for every year between N F and R z for the time period 1967–1985. The distribution of monthly counts of grouped solar flares N f has also been compared to the number at high velocity solar-wind streamers for the same period.  相似文献   

18.
We have detected new HD absorption systems at high redshifts, z abs = 2.626 and z abs = 1.777, identified in the spectra of the quasars J0812+3208 and Q1331+170, respectively. Each of these systems consists of two subsystems. The HD column densities have been determined: log N HDA = 15.70 ± 0.07 for z A = 2.626443(2) and log N HDB = 12.98 ± 0.22 for z B = 2.626276(2) in the spectrum of J0812+3208 and log N HDC = 14.83 ± 0.15 for z C = 1.77637(2) and log N HDD = 14.61 ± 0.20 for z D = 1.77670(3) in the spectrum of Q1331+170. The measured HD/H2 ratio for three of these subsystems has been found to be considerably higher than its values typical of clouds in our Galaxy.We discuss the problem of determining the primordial deuterium abundance, which is most sensitive to the baryon density of the Universe Ωb. Using a well-known model for the chemistry of a molecular cloud, we have estimated the isotopic ratio D/H=HD/2H2 = (2.97 ± 0.55) × 10−5 and the corresponding baryon density Ωb h 2 = 0.0205−0.0020+0.0025. This value is in good agreement with Ωb h 2 = 0.0226−0.00060.0006 obtained by analyzing the cosmic microwave background radiation anisotropy. However, in high-redshift clouds, under conditions of low metallicity and low dust content, hydrogen may be incompletely molecularized even in the case of self-shielding. In this situation, the HD/2H2 ratio may not correspond to the actual D/H isotopic ratio. We have estimated the cloud molecularization dynamics and the influence of cosmological evolutionary effects on it.  相似文献   

19.
The data from the Apollo-14 and Apollo-16 Active Seismic Experiments have been reanalyzed and show that a power-law velocity variation with depth,v(z)110z 1/6 m s–1 (0<z<10 m), is consistent with both the travel times and amplitudes of the first arrivals for source-to-geophone separations up to 32 m. The data were improved by removing spurious glitches, by filtering and stacking. While this improved the signal-to-noise ratios, it was not possible to measure the arrival times or amplitudes of the first arrivals beyond 32 m. The data quality precludes a definitive distinction between the power-law velocity variation and the layered-velocity model proposed previously. However, the physical evidence that the shallow lunar regolith is made up of fine particles adds weight to the 1/6-power velocity model because this is the variation predicted theoretically for self-compacting spheres.The 1/6-power law predicts the travel time,t(x), varies with separation,x, ast(x)=t 0(x/x 0)5/6 and, using a first-order theory, the amplitude,A(x), varies asA(x)=A 0(x/x 0)–(13–m)/12,m>1; the layervelocity model predictst(x)=t 0(x/x 0) andA(x)=A 0(x/x 0)–2, respectively. The measured exponents for the arrival times were between 0.63 and 0.84 while those for the amplitudes were between –1.5 and –2.2. The large variability in the amplitude exponent is due, in part, to the coarseness with which the amplitudes are measured (only five bits are used per amplitude measurement) and the variability in geophone sensitivity and thumper-shot strengths.A least-squares analysis was devised which uses redundancy in the amplitude data to extract the geophone sensitivities, shot strengths and amplitude exponent. The method was used on the Apollo-16 ASE data and it indicates there may be as much as 30 to 40% variation in geophone sensitivities (due to siting and coupling effects) and 15 to 20% variability in the thumper-shot strengths. However, because of the low signal-to-noise ratios in the data, there is not sufficient accuracy or redundancy in the data to allow high confidence in these results.  相似文献   

20.
A method for the determination of the background radiation temperature in earlier cosmological epochs at redshiftsz>2 is discussed in detail. The method is based on the fact that in the clouds situated at cosmological distances at redshiftz the background radiation temperature must be (1+z) times more than in the modern epoch (z=0). This shall affect the level populations of the atoms, ions and molecules and, consequently, the parameters of the absorption lines observed in quasar absorption spectra. It is proposed to use the transition3 P 03 P 1 ofCi (=610 ) for the measurement of the background radiation temperature. Atz>2 this absorption line shifts to the millimeter radio region and can be observed by radioastronomical methods.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号