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 31 毫秒
1.
Using the model of the Galaxy presented by Eggen, Lynden-Bell and Sandage (1962), plane galactic orbits have been calculated for several southern high-velocity stars which possess parallax, proper motion, and radial velocity data. Extensive lists of both raw and computed data for these stars are included. Published values ofU-B andB-V for some of these stars were used in plots of each of the orbital parameters versusU-B, B-V, or the ultraviolet excess (U-B). Also, a comparison is made between the H-R diagrams for the southern high-velocity star group and that of M3, a globular cluster, and again for M67, an old open cluster. The high-velocity star group is found to resemble an old open cluster more than a globular cluster.  相似文献   

2.
In this paper independent evidence in favour of the hypothesis proposed by Thakur and Sapre (1979) that a QSO consists of a bright central object embedded in an extended nebulosity has been presented. U–B and B–V , the spectral indices in (U-B) and (B-V) colours, have been calculated for a sample of 80 QSOs with redshiftz0.76. In Figure 1 = ( B–V – U–V ) has been plotted against = ( B–V + U–B )/2. In this figure the QSOs in which detectability of neubulosities has been predicted by Thakur and Sapre (1979) occupy a separate but adjacent part of the diagram as compared to those for which such a prediction has not been made. In Figure 2 (U-B)0 has been plotted against (B-V)0 for the same sample of 80 QSOs, where (U-B)0 and (B-V)0 are the (U-B) and (B-V) colours corrected for galactic extinction. In this plot also, a similar separation of the two classes of objects is discernible. Another empirical criterion—namely, (B-V)00.32 for the detectability of nebulosities around QSOs—has been suggested.  相似文献   

3.
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   

4.
We show that the relation ln(1+z)=0.206 proposed to describe the discretization of the spatial distribution of quasars is a consequence of observational selection and is predetermined by the choice of the photometric system (U, B, V, R), the ratios of the wavelengths of the emission lines of Mg II, C III, C IV, Ly and the absorption lines O VI (1035 å) of the quasars studied.Translated fromAstrofizika, Vol. 37, No. 4, 1994.In conclusion I express gratitude to L. V. Mirzoyan for constant interest and moral support in the course of the present work and to G. A. Arutyunyan for valuable advice.  相似文献   

5.
The bivariate spectral type-luminosity class distribution combined with thez-distribution and broad-band photometric data have been used in order to derive integrated colors in Johnson's UBVRIJKL system for the solar neighborhood.The frequency distribution of white dwarfs is also taken into account for theU-B, B-V colors.  相似文献   

6.
TheUBV photometry of 105 bright stars and theU magnitudes of 36 bright stars in M33 taken by the 2 m RCC telescope of the Rozhen Observatory at the Bulgarian Academy of Sciences were used to obtain colour-magnitude and colour-colour diagrams. A criterion forV, B-V, andU-B is suggested which facilitates the separation of the member stars from the foreground stars. The vast majority of the bright blue stars with strong negativeU-B are M33 members. The existence of objects with an unusual combination of colours (B-V>0.5 and strong negativeU-B) has been confirmed.  相似文献   

7.
The photoelectricV observations of the Scuti star 59 Aur have been analysed using the techniques of periodogram analysis and least-squares solutions. The fundamental mode is found to be more prominent than the first overtone in the pulsation of 59 Aur. The period ratio of the first overtone to the fundamental (i.e.,P 1/P 0=0.748) indicates that the star pulsates in the radial mode. The absolute magnitude, effective temperature and mass of the star are derived to be 1 . m 22, 7300 K and 2.0M , respectively. No variations exceeding±0 . m 01 about the mean values ofB-V andU-B colours have been found during a pulsation cycle.  相似文献   

8.
We adopt the iterative least-squares method of Schmee and Hahn (1979) and extend it to the multiple regression case to investigate the dependence of the X-ray luminositíesL x of quasars on their optical liminositiesL 0 and redshiftsz. The method has several advantages, one of which is that we do not need the strong assumption that the values of the optical-X-ray index 0x of the detected and nondetected quasars should fall into the same range. We have found that correlations of 0x and log(1+z) or the look back time (z) are shown, but these are not firmly established due to the uncertainty present in the regression parameter. On the other hand, it is impossible for 0x to be independent ofL 0. We have also shown thatL x is less than proportional toL 0.  相似文献   

9.
The spectrophotometric method for computing the apparent stellar diameters, proposed by Chalonge and Divan (1950) and modified by Fracassini and Pasinetti (1967) has been applied to 172 B5V-A5V stars (single and belonging to galactic clusters) of the Catalogue of Geneva Observatory (Rufener, 1971). In the straight line diagrams log vsm, drawn for the stars of the same spectral type, it is possible to identify some peculiar stars (with peculiarities in the diameter or monochromatic brightness). The agreement with the values of the apparent diameters of Leo, Ori, Lyr and CMa, obtained by Hanbury Brownet al. (1967), is very good. The comparison with the diagramss v vs (B-V)0,R vs (B-V)0 deduced by Wesselink (1969), seems satisfactory. The comparison with the results obtained by other authors and the great number of stars which will be observed in the photometric system in seven colors of Geneva, demonstrate the wide possibilities of this spectrophotometric method for determining the apparent stellar diameters.
Sommario Il metodo spettrofotometrico di Chalonge e Divan (1950) per il calcolo dei diametri stellari apparenti, modificato da Fracassini e Pasinetti (1967), è stato applicato a 172 stelle B5V-A5V (isolate e in ammassi galattici) del Catalogo dell'Osservatorio di Ginevra (Rufener, 1971). Costruiti i diagrammi lineari log -m v per i vari gruppi di stelle dello stesso tipo spettrale, è possibile identificare alcune stelle peculiari con diametri e brillanze monochromatiche anomale. Il confronto con i diametti apparenti di Leo, Ori, Lyr e CMa determinati da Hanbury Brownet al. (1967) mostra un accordo molto buono. Il confronto con le relazionis v -(B-V)0eR-(B-V) 0 ottenute da Wesselink (1969) appare soddisfacente. Il confronto con i risultati ottenuti da altri autori e il grande numero di stelle che saranno osservate nel sistema fotometrico in sette colori di Ginevra, dimostrano le ampie possibilità di questo metodo spettrofotometrico per la determinazione dei diametri stellari apparenti.

Thesis for the degree on Applied Physics.  相似文献   

10.
We present evidence for Ly pumping of the Lyman band system of molecular hydrogen in Herbig-Haro 7 and the bipolar outflow DR 21. For this study we have measured several vibrational-rotational emission lines of H2 whose energy levels are widely spaced and ranging from 6000 (v = 1) to 25000 Kelvin (v = 4). We show that the near-infrared H2 emission from the shocked gas in HH 7 can be well described by a bow C-type shock. The enhanced emission observed from the higher energy levels (v > 3) can be well modelled by employing the Ly pumping mechanism.In the DR 21 outflow the multi-line study showed that different physical conditions exist in the eastern and western emission lobes. The higher H2 line ratios measured in the eastern lobe suggests a higher Ly pump rate which may be locally produced in the fast bowshocks. The FUV radiation field emanating from the central HII regions may in addition be exciting the Lyman and Werner bands of H2 in the molecular lobes.We show that the observed H2 emission can be interpreted in terms of a simple model consisting of a C-type bowshock, which produces the low excitation H2 emission, and a FUV radiation field with enough Ly line radiation to produce the high excitation H2 emission through fluorescence.  相似文献   

11.
UBV measurements of the light of the night sky in the auroral zone during three seasons are presented. The mean brightness of the night sky in theV band is found to be equal one 18m1 star (arc sec)–2, with considerable variations. The observed meanB-V andU-B indicies are +0 . m 7 and –1 . m 6, respectively.Light curves of variable stars during strong auroral activities are also shown. On the basis of measurements we briefly discuss the possibility of accurate stellar photometry in the auroral region.  相似文献   

12.
It is known that the correlation between the observed visible luminositym(z), angular dimension (z) of galaxies on the red shiftz and theoretical relations of the standard cosmology is possible only under the assumption that the luminosity and object dimension evolution are equal toL(z) =L 0(z + 1)3.2 andl(z) =l 0(z + 1)–2, respectively. This evolution is hypothetical, since it is defined by a theory which is not confirmed by experience. In order to solve the problem on the reality of the Universe expansion, it is sufficient to prove or disprove these conclusions using methods of measurement independent of the theory. One of these methods consists of defining the dependence of the radiation spectra of galaxies and quasars onz which evidently is proportional to the spectrum of absolute luminosityL(, z). It has subsequently been shown that the spectrum form is practically independent of the red shift - i.e., it remains constant during the lifetime of galaxies and quasars. Consequently, to explain the luminosity increase required by the standard cosmology, it is necessary to admit a completely unreal entity (at all wavelengths of the optical spectrum increase) of the radiation spectral density of (z + 1)3.2 times. We can conclude that in reality the luminosity evolution is either absent or its power index is smaller at least by an order of magnitude. It is likely, therefore, that the established is the result of an inadequate standard in cosmology.Another method is the use of the observed relations between the parameters ofL andl galaxies. A number of measurements made by different authors gives the relationlL a , where 0.33a1.6. It then follows thatl(z)(z + 1)3.2a . This dependence of the galaxy dimension is inverse to the dependence predicted by the standard cosmology. Besides, in order to make a correlation between thel(z)(z + 1)3.2a and measurements of (z), it is necessary that indices of the degree of luminosity evolution should be smaller by an order of magnitude.Thus, the luminosity increase and simultaneous decrease of galaxy and quasar dimensions predicted by the standard cosmolog are not confirmed by the direct astrophysical measurements. This discrepancy is the consequence of an incorrect hypothesis of Universe expansion and the relativistic cosmology based on it.  相似文献   

13.
The photoelectric light curves of XY Cet of Srivastava and Padalia (1975) and of Morrison and Morrison (1968), from which considerably different sets of photometric elements have previously been deduced, were re-analyzed in detail. The elements derived in the present study from Srivastava and Padalia's (1975)UBV observations arer g=0.157±0.006 (p.e.),r s=0.142±0.007,i=88°.4±0°.5,L g=0.600±0.017, 0.602±0.015 and 0.584±0.018 forU, B andV, respectively. It is also found from their light curves that the system has an eccentric orbit withe cos =0.0026±0.0005. The elements deduced from theV observations of Morrison and Morrison (1968) are found to be in satisfactory agreement with those presented above.The existence of theAm characteristics of both components, which was recognized by earlier spectroscopic observations, are supported by theB-V andU-B color indices and [m 1] value of the system. Both components are also found to have appreciably evolved, as expected for metallicline stars.  相似文献   

14.
We study the classical problem of two-dimensional motion of a particle in the field of a central force proportional to a real power of the distancer. for negative energy and (0, 2), each energy levelI h is foliated by the invariant toriI hc of constant angular momentumc and, by Liouville-Arnold's theorem, the flow on eachI hc is conjugated to a linear flow of rotation number h (c).A well-known result asserts that if we require h (c) to be rational for every value ofh andc, the, must be equal to one (Kepler's problem). In this paper we prove that for almost every (0, 2) h (c) is a non-constant continuous function ofc, for everyh<0. In particular, we deduce that motion under central potentials is generically non-periodic.Partially supported by CIRIT under grant No. EE88/2.  相似文献   

15.
In the present paper n 0 , for occulation and transit eclipses of partial phases, are evaluated numerically by means of the Runge-Kutta methods. Section 2 contains the required differential equations of n 0 with respect to the modulusX orC, and Section 3 includes the numerical method of the solutions of these differential equations. Theoretical values of 0 0 and 1 0 , with corresponding values ofC, are also added in this section.  相似文献   

16.
It has empirically been shown that, for a given value of the effective temperature, the correction in (B-V) due to line blanketing varies linearly with the metallicity parameter S. Next, on the basis of considerations different from those used to obtain a similar result by Sturch (1966), a relation between reciprocal effective temperature e (=5040/T e ) and intrinsic line-free colour index(B-V) o,c has been obtained based on the e and (B-V) values for five RR Lyr variables. Relations between e and intrinsic colour(B-V) o for different groups of stars having a S parameter in the range 0S11 have also been obtained.  相似文献   

17.
UBV photoelectric observations of the W UMa-type binary V471 Cas were made from September to November 1984. Its colour indices were found to be(B-V)=0 . m 771±0 . m 02 and(U-B)=0 . m 196±0 . m 02. TheU, B, andV light curves of V471 Cas show some photometric fluctuations. We found that its orbital period is not 0.335998 days which was given by GCVS (1986), but 0.405356 days.Photometric orbital elements of V471 Cas were found using the Wilson-Devinney method. V471 Cas is a contact system, in which the overcontact factor is 0.19, its mass ratio of two components is 0.5947, and orbital minclination is in 83.29 degrees.  相似文献   

18.
The surface photometry of S254–S257 has been carried out by means of a wide range image processing technique in the reduction system. The photographic plates in the H+[NII] andV-bands are taken with the Schmidt telescope. Especially, we have obtained the calibrated map of theHii region, superposing two or more plates with different exposure times, and removing the star images. Three kinds of calibrated maps of theHii regions are drawn: (1)E-map in the (H+[NII]+continuum) (2)V-map in the continuum atV-band, (3)(E-V)-map in the (H+[NII]) line emission. The intensity profiles across the nebular centers were also obtained. Based on calibrated maps, the morphological structure and mass distribution of S255 and S257 are discussed. The location of observed nebulae on the (m H–m v) diagram, wherem H andm v denote the surface brightness, expressed in the magnitude per square arcmin, is shown together with that of some other nebulae. Some arguements on the age sequence of observedHii regions are presented.  相似文献   

19.
A comparison between model atmosphere grids with and without metal blanketing has been performed in the low-temperature range (T eff=6000 K to 10000 K) and for different metal contents (logA=0, –1, –2;A=scaled solar abundance). ForA10–1 andT eff7000 K, the Johnson colour indicesU-B andB-V, together with the Strömgrenu-b, b-y and the bolometric correction (BC) are little affected by metal blanketing ( mag<0 . m 04). On the other hand, the trend of the physical quantities and them 1 andc 1 colour indices reflect the inadequateness of the models even withA=10–2 andT eff=9500 K, where hydrogen line blanketing is expected to dominate. This fact discourages once and for all the use of metal unblanketed atmospheres other than for comparison of colour indices or the calculation of bolometric corrections for Population II A-F spectral types.  相似文献   

20.
Preliminary study of the eclipsing binary AB Cas is presented here by using the photometric observational data. The primary component is one of the Sct variables with period of 0d.054, and whether the oscillation is of a radial mode or of a non-radial one is discussed. Two colour indices (B-V andU-B) data and the light curve analysis suggest that this binary system is a typical Algol type binary system, in which the primary component is near the ZAMS with about 2.3M and the secondary one is a subgiant star with about 0.5M .  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