共查询到20条相似文献，搜索用时 31 毫秒
1.
M. Kuturaç C. Ibanoğlu Z. Tunca A. Y. Ertan S. Evren O. Tümer 《Astrophysics and Space Science》1981,77(2):325-346
The RS CVn-type eclipsing binary AR Lac has been observed in two colours,B andV, in 1978 and 1979. Several times of minima have been obtained during the observations and the new light elements have been calculated. The orbital period of the system was found to be decreasing with an amount of 14.6 s century–1.The light curves of the system obtained inB andV show a significant wave-like distortion outside eclipses. The amplitudes of the wave-like distortion inB andV are about 0
.
m
09 and 0
.
m
10 in 1978, and, 0
.
m
12 and 0
.
m
13 in 1979, respectively. The minima of the wave-like distortion have shifted with an amount of 0
.
p
40 in one year, thus indicating the migration period of the wave-like distortion is about 2.5 yr.A noticeable variation of light during the totality of primary minimum has also been observed. This variation can be attributed to the distortion wave which has been moving towards decreasing phases. 相似文献
2.
A. Y. Ertan O. Tumer Z. Tunca C. Ibanoĝlu M. Kurutac S. Evren 《Astrophysics and Space Science》1982,87(1-2):255-268
The eclípsing binary AR Lac has been observed in two colours,B andV, in 1980 and 1981. The new times of minimal obtained during the observatons indicate that the period of the system is still continuing its decrease. The wave-like distortions outside eclipses have two maxima and are very similar in shape in successive two years. 相似文献
3.
S. Evren 《Astrophysics and Space Science》1985,108(1):113-123
The RS CVn-type eclipsing binary star MM Her has been observed in two colours,B andV, in 1979, 1980, and 1983. Several minima times were obtained during the observations and new light elements calculated. The light curves of the system obtained in blue and yellow lights show a significant wave-like distortion which migrates towards the decreasing orbital phases. Its migration period was estimated to be about 3.5 yr. The amplitudes of the wave-like distortion inB andV appear to change each year. The primary minimum of the system is a total eclipse with a duration of 0d.08. 相似文献
4.
David L. Rabinowitz 《Icarus》1997,130(2):287-295
This paper predicts the size distribution of the Earth-approaching asteroids with diameterd= 10 m to 10 km, assuming they originate as the fragments of main-belt asteroids with a cumulative size distribution proportional tod−2.5and that they have self-similar fragmentation properties. The resulting distribution is dominated by “fast-track” bodies originating from parent asteroids with orbits close to the 3:1 mean-motion resonance with Jupiter. Because the dynamical lifetimes of these Earth approachers are shorter than their collisional lifetimes, their size distribution is nearly proportional tod−3.0, the production distribution in the main belt. This prediction, however, is at odds with the Spacewatch observations. The observed distribution is relatively flat ford> ∼100 m, and relatively steep ford< ∼100 m, so that the number of Earth approachers withd∼ 10 m to 0.3 km is overestimated. If these populations are predominantly of main-belt origin, then the size distribution in the main belt is not a simple power law. A nonuniform size distribution with wave-like oscillations, possibly caused by a cutoff at small sizes, would lead to Earth approachers with a size distribution in better agreement with the observations. If such wave-like oscillations are realistic, then the main belt is sufficient to supply the observed number of Earth approachers throughout the observed size range. 相似文献
5.
S. Evren 《Astrophysics and Space Science》1987,137(1):151-166
The RS CVn-type eclipsing binary MM Her was observed photoelectrically inB andV colours. The light curves obtained in 1984 and 1985 are presented. It was found that the depths of the primary minima are decreased from 1983 to 1985. However, the amplitude of the wave-like distortion outside the eclipses was detected to increase since 1976. The period of migration was determined to be about 3.57±0.08 years. 相似文献
6.
The eclipsing binary UV Piscium was observed with the standardUBV filters during 1976-77, 1977-78 and 1978-79 observing seasons with the 1.22-m reflecting telescope of the Japal-Rangapur
Observatory. A wave-like distortion on the light curve noticed by Carr (1969), Oliver (1974), Sadik (1979) and Zeiliket al. (1982a) is confirmed by the present observations. Combining our observations with those of Carr, Oliver and Sadik, it is
found that the distortion wave is moving towards decreasing orbital phase with a period of about 1200 days. The source of
the observed distortion wave is found to be the hotter component. 相似文献
7.
M. Can Akan 《Astrophysics and Space Science》1988,143(2):367-376
Two-colour photoelectric light curves of the RS CVn-type eclipsing system UV Psc, obtained in 1985 and 1986, are presented. Present work also deals with the Fourier analysis of the outside-eclipse light variations for five years' light curves (1981, 1982, 1984, 1985, 1986). Based on this analysis, the amplitude variations of the so-called wave-like distortion and its migration period have been investigated. The amplitude of the wave-like distortion seems to vary with a very rough period of 4–5 years, and the migration period of the wave minimum appears to be one of the three different (2.3, 0.7, 0.4 years) but most possible values among some others. 相似文献
8.
Stellar occultations have shown that vertical profiles of density fluctuations in the atmosphere of Pluto typically show wave-like structure with an amplitude of a few percent and vertical wavelengths of a few kilometers. Here we calculate the tidal response of Pluto’s atmosphere to solar-induced sublimation “breathing” from N2 frost patches. Solutions show global-scale wave-like density structure capable of explaining the observations. The atmospheric response is a combination of eastward and westward migrating tides, together with a zonally symmetric mode. Calculated vertical wavelengths and amplitudes are similar to observations. 相似文献
9.
R. K. Srivastava 《Astrophysics and Space Science》1988,140(2):337-351
FirstUBV photoelectric photometry of the eclipsing binary system Cap has been presented. An improved period of 1d.022766 has been given. The duration of primary eclipse comes out to be more than double the duration given earlier. The depth has also been found to have increased. The light changes during eclipses show slight asymmetry. Eccentricity appears to be present in the system. Light and colour curves show variations. Primary component appears to be surrounded by a disc, the size of which is comparable to the size of the primary component. Two dips are seen around phases 0.20 and 0.67, the first appears more definitive, and is attributed to the wave-like distortion, like the one found in RS CVn binaries. The discussion reveals that Cap is a very complicated system. 相似文献
10.
Photoelectric observations of eclipsing binary RS CVn carried out at Uttar Pradesh State Observatory Nainital, have been reported. The light curve shows wave-like distortion. Colours and magnitudes of RS CVn and comparison stars BD+35°2421 and BD+35°2422 have been given. 相似文献
11.
The dynamical properties of a realisticthermal-structure interface between a coronal loop and the chromosphere/photosphere are investigated by numerical simulations using acoustic and Alfvénic excitations. These properties are relevant to the end conditions seen by coronal MHD perturbations (e.g., waves or instabilities), in the absence of much slower energetics effects. Analytic studies of coronal-loop hydromagnetics have often made simplifying assumptions about the boundary conditions at the loop base in order to make their calculations tractable. However, in the presence of a transition region and chromosphere with rapidly varying plasma conditions, it is not clear how valid these heuristic assumptions are. In this study, we find that the discontinuous fluid-density model approximately represents the reflection/ transmission scaling with respect to varying transition-region density and temperature (i.e., dynamic impedance) ratios, although it does not quantitatively predict the chromospheric response to wave-like coronal activity. This disagreement is partially due to the finite width of the corona-to-photosphere transition. 相似文献
12.
O. V. Kozlova 《Astrophysics》2004,47(3):287-299
The results of high-resolution long-term spectral monitoring of Herbig Ae star HD 179218 in the region of emission H line and the sodium resonance doublet Na I D are presented. The received data show the existence of short-term variability (about 10 days) and long-term wave-like variability of equivalent width EW, intensity of circumstellar (CS) emission I and parameters of H emission profile. The analysis of these data allows us to suppose the existence of the global variability of parameters of accretion disk. 相似文献
13.
C. Ibanoĝlu S. Evren O. Tümer A. Y. Ertan Z. Tunca 《Astrophysics and Space Science》1983,95(2):409-416
Two-colour photoelectric observations of LX Per carried out at Ege University Observatory in 1981 and 1982 observing seasons are presented. The light curve of the system has a wave-like distortion which migrates towards the decreasing orbital phase. The period of the retrograde migration of the wave-like distortion has been determined as 475 days. The amplitude of the wave appears to change with time periodically. 相似文献
14.
S. Evren 《Astrophysics and Space Science》1988,140(1):125-130
The double-lined spectroscopic and eclipsing binary ER Vul was observed in blue and yellow light during the 1984 and 1985 observing seasons. In 1984 four and in 1985 three different light curves in each colour were obtained. The system sometimes is too active and sometimes too quite. The wave-like distortion has been obtained for each light curve and a period of migration has been estimated to be about 8–9 months. The light fluctuations, which are the main characteristics of ER Vul, seems to be related with the wave minimum, (e.g., spotted regions) of the component(s). 相似文献
15.
V.N. Mel'nik A.A. Konovalenko H.O. Rucker A.A. Stanislavsky E.P. Abranin A. Lecacheux G. Mann A. Warmuth V.V. Zaitsev M.Y. Boudjada V.V. Dorovskii V.V. Zaharenko V.N. Lisachenko C. Rosolen 《Solar physics》2004,222(1):151-166
We present the results of radio telescope UTR-2 observations of solar Type II radio bursts in the 10–30 MHz frequency range. These events possess a fine structure consisting of fast drift sub-bursts similar to Type III bursts. The frequency drift rate of the Type II bursts at decameter wavelengths is smaller than 0.1 MHz s–1. One of these bursts with herringbone structure has a wave-like backbone that almost does not drift. The features of the observed bursts are discussed. 相似文献
16.
In this paper we present the observations of the eclipsing binary LX Per, which were obtained in 1983. There is a wave-like distortion at outside eclipses with an amplitude ranging from 0.03 to 0.08 mag. The wave-like distortion was removed with a new approach. Then, the light curves were analyzed by the methods of Wood and Nelson, Davis, and Etzel. The absolute parameters of the components were also calculated. The physical parameters of the components indicate that the cooler star has seperated or has been departing from the Main Sequence. 相似文献
17.
S. Evren A. Y. Ertan Z. Tunca C. Ibanoĝlu M. Kurutaç O. Tümer 《Astrophysics and Space Science》1982,87(1-2):51-59
Two-colour light curves of Z Her were obtained observing the system from 1978 to 1981. The wave-like distortion at outside eclipses were derived. The amplitudes of the wave increase and its minimum migrates towards the decreasing orbital phase with a period of about 1.4 yr. An attempt was made to represent the wave-like distortions with a truncated Fourier series. The representation was found to be unsatisfactory since the distribution of the present observations is not regular but forms separate groups along the time axis. Therefore, further observations to cover the phases evenly in between the minima are needed. 相似文献
18.
C. Ibanoĝlu 《Astrophysics and Space Science》1987,139(1):139-147
Two-colour photoelectric observations of the short-period RS CVn-type eclipsing binary UV Psc have been made between 1981–1986 at the Ege University Observatory. The present work deals with the light curve variations of the binary obtained in the observing seasons of 1981, 1982, and 1984. The shape of the light curve, the depths of the minima, and the total brightness of the system seemed to change in the course of time that covers three years of observing time. The value of the migration period of the wave-like distortion was roughly estimated to be between 1.5 and 2.0 years. 相似文献
19.
The secular evolution of the pulsation period of δ Cephei, η Aquilae, and ζ Geminorum during a cumulative total of 577 years suggests wave-like departures about the smooth time trends. 相似文献
20.
Maurizio Ternullo 《Solar physics》1987,112(1):143-151
This work is a study of the rotational properties of the solar calcium plages, during the time interval 1967–1977; only plages older than 4 days have been the object of this research. We have looked systematically for any significant change occurring during the course of the solar cycle, and any kind of ‘anomaly’ or fine structure in the differential rotation latitudinal profile. We find that such a profile undergoes a cyclic transformation, making it assume the highest steepness at the solar maximum; a sudden flattening then occurs in the first years of declining activity; the last years of the cycle, as the first years of the next one, are characterized by intermediate steepness values. Moreover, we find that, in spite of the general belief that the angular rotation rate is continuously decreasing with increasing heliographic latitude, at least two inversions do exist of such an overall tendency:
- A narrow, minimal angular-rotation-rate strip lies very close to the equatorward margin of the plage production band; this feature shifts continuously, in a wave-like manner, throughout the solar cycle, from 15/18° to 3/6° latitude.
- A narrow, maximal angular-rotation-rate strip has been observed lying in the neighbourhood of the poleward margin of the activity band; a process of continuous transformation of the rotation rate profile is always active, in a narrow latitude strip on the equatorward side of such a feature, generating new features of the same kind, which replace the older ones, that disappeared due to the equatorward shift of the plage zone. All that simulates an equatorward shift of the observed ‘anomalies’; we observed them until the minimum activity epoch (1976), at 15/18° latitude. Some relations of these features with both torsionai waves (Howard and LaBonte, 1980) and magnetic activity are briefly discussed.