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11.
On the basis of more abundant data a relation logPV/logR for cepheid variables (Fernie, 1965) is constructed. A linear relation between logP V and logR for classical cepheids is found, which perhaps has a break at R=10R
. On the logR/logP diagram thes-cepheids (Efremov, 1968) show a distinct sequence. Alls-cepheids present a relative variation of the radii R/R0.075. The existence of non-s-cepheids with R/R0.075 raises a point about the evolutionary place of these stars (see Efremov, 1968). One could suppose that cepheids with logP>1.1 pulsate in the first overtone. 相似文献
12.
On the basis of the PLC relation (1) or the PL relation by Van den Bergh (2) and the PC relation by Deanet al. (1978), the distances of 284 galactic cepheids with photoelectric observations have been derived. The space distribution of these cepheids with 111 additional ones without photoelectric observations, is studied. In spite of the strong influence of the absorption matter, which makes a great number of distant cepheids unknown (Figure 4), a conclusion is drawn that the cepheids do not trace spiral arms with only one possible exception: the Carina arm. The cepheidz-coordinate distribution confirms the finding of Fernie (1968) that the cepheid layer is inclined towards the formal galactic plane. On the basis of cepheid space density, a number of vast star complexes (Table I) are identified in which other young objects, together with cepheids fall. The existence of these complexes is explained by star formation in giant molecular clouds. The cepheid mean period increase towards the galactic centre is most probably connected with the existence of a ring between the Sun and the centre of the Galaxy, with the highest density of hydrogen and the highest rate of star formation. 相似文献
13.
14.
An estimate of the period of the rotation of the line of apsides of the double-star system Phe is obtained by representing the density function as a product of a normal Gaussian distribution and an associated Legendre polynomial
.The asymptotic behaviour of this function coincides with the results obtained by Zeldovichet al. (1981).The period of motion of the line of apsides of Phe (about 63 years) obtained in this way comes close to the period determined by an empirical formula for
of Batten (1973). 相似文献
15.
Some consequences from new data on the photometrically obtained intrinsic colours are considered. It is shown that the small amplitude and almost sinusoidal light-curve cepheids (Cs-subtype) increase their pulsation amplitude towards the red instability strip edge, differing from the other galactic cepheids. This feature is discussed in connection with Efremov's (1968) hypothesis that the Cs-cepheids first cross the instability strip from left to right. The galactic cepheid period-colour relation obtained by Dean, Warren and Cousins (1978) satisfies rather well the LMC cepheid observations and, consequently, considerations for the period-luminosity relations are made. The residuals from the PL relation proposed by us (AA line instead of Gascoigne's BB line in Figure 3) correlate with the colour residuals from the DWC period-colour relation V/(B–V) being equal to 2.7 (Figure 4). The luminosity effect as a possible cause of the descrepancy between the spectroscopic cepheid colours and the photometric colours is briefly discussed. 相似文献
16.
Viara Minkovska Bernard Peybernès Pierre Cugny Todor Nikolov 《Comptes Rendus Geoscience》2004,336(10):931-938
Within the Emerici zone–Barremense zone biostratigraphic interval, the Barremian deposits of Central Fore-Balkan (Lovech–Veliko Tarnovo shelf) consist of a succession of several formations where alternate terrigenous argillaceous/sandy-dominated facies (Kormjansko Fm., Balgarene Fm.) and carbonate-dominated (‘Urgonian’) facies (Krushevo Fm., Emen Fm.). The qualitative and, particularly, quantitative facies analysis of the carbonate successions observed along 13 detailed cross-sections and in one drill hole show the stacking of about 40 fifth-order T–R cycles induced by numerous eustatic jerks contributing to the progressive settlement of this shelf. These high-frequency cycles of about 100 000 years must be regarded as valuable correlation tools for the subsurface hydrocarbon research. To cite this article: V. Minkovska et al., C. R. Geoscience 336 (2004). 相似文献
17.
The possibility the turbulent atmosphere to act as a cause for an amplification of the optical star images is considered. This is made on introducing the turbulent atmosphere a an optical collimator set. Some considerations about the modelling and formalization of this effect are made. Finally some consequences relative to the optical record photometrical information extraction are mentioned. 相似文献
18.
We used the catalogue of the mean light-curves and colours of the Cepheids in the UBV system (Nikolov, 1968), for 240 Cepheids, and constructed the curves which represent plots of their U-B versus B-V colour indices. These curves form three groups: linear curves, open curves, and curves possessing a loop. An opinion that the presence of a loop may be a criterion for Population II objects is not confirmed.It is shown that the slope of such curves (corrected for reddening) with respect to the B-V axis increases with the period. The area delimited by the curves on the U-B/B-V diagram remains almost the same up to a period of about 9 to 10 days, whereafter it increases with the period. The possible causes for this behaviour of the Cepheids on the colour-colour diagram, which is connected with the ultraviolet emission of these stars, are discussed. 相似文献
19.
On the basis of the intrinsic (U – B)0 colours of the cepheid variables, found by the authors, the UV-excesses in the maximum and minimum light δ(U – B)max and δ(U – B)min are defined. It is found out that the UV-excesses in the maximum light δ(U – B)min increase with the period P (Fig. 2), but there is no correlation between δ(U – B)min and log P. A correlation between δ(U – B)max and the “amplitude defects” fB is also determined. These results in connection with some other considerations, as well as the possible causes of the UV-excesses, are discussed. 相似文献