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.
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
3.
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
4.
U, B, andV observations of AR Lacertae, obtained in 1981, have been presented alongwith the colour indices. A distortion wave minimum is found to lie at 0
.
P
21. The amplitude of the wave minimum inV filter is too weak, while it is stronger inU andV filters, the strongest being inV filter. The period of the migration wave turns out to be 2.53 yr. 相似文献
5.
B andV observations of the eclipsing binary RU Eridani made on 23 nights during 1974–76 are reported. An improved period of 0d.63219951 is derived. After rectification ofB andV light curves, new elements are derived using Russel-Merrill method. The system is classified as semidetached. 相似文献
6.
Z. Tunca 《Astrophysics and Space Science》1984,105(1):23-31
The RS CVn-type eclipsing binary SZ Psc was observed in two coloursB andV, in 1981. The rate of change of the period was calculated using two different least-squares procedures. The amplitudes of the light variations at outside eclipses are 0
.
m
181 and 0
.
m
213 inB andV colours, respectively. The light curves of the system have been solved using a new approximation. The radius of the cooler component is only 82% of its Roche-radius and the system is detached one. 相似文献
7.
PhotoelectricB andV observations of the W UMa-type system OO Aql have been obtained for 11 nights during the period from 22 June–30 July, 1987. A total of 978 observations were obtained in eachB andV filter. All these observations were transformed to theB andV colours of theUBV standard system. Five light curves for primary and secondary eclipses were obtained, its times of minima were determined and a new linear ephemeris was given. The period changes of the system were discussed. 相似文献
8.
SW Lacertae is a short-period variable star of the W UMa-type. A total of 261 photoelectric observations for eachU, B, andV filter were obtained in 1986 while 522 photoelectric observations for eachB andV filter were obtained in 1987. All these observations were transformed to theU, B, andV colours of theUBV standard system. Nine light curves for primary and secondary eclipses were obtained, their times of minima were determined and a new linear ephemeris was obtained. The period changes of the system were also discussed. 相似文献
9.
Z. Tunca V. Keskin M. C. Akan S. Evren C. Ibanoğlu 《Astrophysics and Space Science》1987,136(1):63-76
B andV observations of the W Ursae Majoris-type eclipsing variable system AK Her were made on five nights at the Ege University Observatory. Several times of minima were obtained during the observations and the new light elements were calculated. The light-time period was found to be about 75.72 years. The light curve of the system appears to change in each cycle for both colours. The secondary minimum of the system seems to be a total eclipse with a duration of about 42
m
.5. 相似文献
10.
U, B, andV observations of RZ Eri have been reported. Colours of comparison stars BD-10°994, BD-10°996 and of the variable RZ Eri have been presented. The observations of RZ Eri do not indicate the distortion wave in the light curve beyond observational scatter. 相似文献
11.
Farouk M. Mahmoud 《Astrophysics and Space Science》1993,209(2):237-253
Sinusoidal variations in bothV - andB-bands were detected in some flare stars of the UV Ceti type outside of flares. This detection has confirmed the light variation detection in Johnson'sV -band in EV Lac at quiet-state luminosity by Pettersen (1980) with a cyclic period equals about 4
.
d
378 and an amplitude of about 0
.
m
07. An interpretation of these short cyclic periods is that they are due to intensity modulations from a photospheric spot group as a result of stellar equatorial rotations. A short period of 14 days with an amplitude of 0
.
m
099 was detected inB-band in AD Leo. For the two flare stars, BD+55° 1823 and DO Cep in bothV- andB-bands, cyclic periods of more than 3 days and less than 17 days with amplitudes more than 0
.
m
090 and less than 0
.
m
250 have been registered. A significant contribution has been found in the flare star EV Lac in bothV- andB-bands at its quiescent-state luminosity where the detected cyclic periods are agreed with that which was detected by Pettersen (1980) in the same flare star in Johnson'sV-band, about 4 days. Furthermore, we found the same cyclic period in the colour index,B - V (about 4 days) which strengthens starspot phenomenon. This colour index period could not be detected by Pettersen (1980). 相似文献
12.
K. R. Pollard J. B. Hearnshaw A. C. Gilmore P. M. Kilmartin 《Journal of Astrophysics and Astronomy》1989,10(2):139-146
Photoelectric photometry has been obtained for CF Octantis on 39 nights. The object is a member of the RS CVn class and has
a highly active chromosphere. A 20.15 ±0.06 d period has been found from theB andV magnitudes, which is interpreted as the rotational modulation of the light from a non-uniformly spotted star. The amplitude
of this spot wave is observed to vary slowly between ΔV about 0m.l and 0m.3, which may be evidence for an activity cycle of 9 ±3 years. 相似文献
13.
S. Evren 《Astrophysics and Space Science》1988,143(1):123-136
In this work,B andV photometry of the RS CVn-type binary II Peg is presented. The light curves obtained in 1983 and 1984 display two unequal maxima. The light curves of the system have different amplitudes. The amplitude seems to vary with three different periods. 10, 6, and 4 years of periods may be attributed to those variations. 相似文献
14.
B andV observations of the suspected variable BV 690 = NSV 04298 are reported. The star shows light variations with a period of
ld.2400 and with amplitudes of 0m.27, 0m.36 and 0m.11 inV, B, andB-V respectively. The light curves show steeper rise than decline, and there is evidence for the presence of a bump in the descending
branch around the phase of 0.35. From considerations of the period, spectral type, presence of the bump and high tangential
velocity we conclude that BV 690 belongs to the BL Herculis class of Typen Cepheids 相似文献
15.
M. Hoffmann 《Astrophysics and Space Science》1982,83(1-2):203-207
Photoelectric light curves of V1022 Oph inB andV are presented. It has been confirmed that it is a W UMa type eclipsing binary with one of the shortest periods known (P<0.d25). Some general properties of the system have been derived.Based on observations made at the European Southern Observatory (La Silla/Chile) 相似文献
16.
The system of ST Aquarii has been observed inB andV filters at KOTTAMIA Observatory in Egypt. Two light curves have been obtained and new times of minima have been calculated.The light curves have been analysed using the theory of Fourier transform of light changes in frequencydomain, and new geometrical and physical elements have been obtained. 相似文献
17.
Photoelectric observations of WX Eridani inB andV filters have been discussed. The maximum magnitudes of the system areB=9
m
.70 andV=9
m
.46. TheB-V colours of the components are 0
m
.16 and 0
m
.80 for the primary and the secondary, respectively, while their spectral types are A5+K0. The period has been found to be constant and its revised value is 0d.823 270 76. 相似文献
18.
Varol Keskin 《Astrophysics and Space Science》1990,169(1-2):165-170
Photoelectric observations of the double-lined spectroscopic and eclipsing binary ER Vul were obtained inB andV colours of Johnson'sUBV system, between 1981 and 1986. The light curves show that the system is sometimes very active and sometimes very quiet and have changes in short time intervals. The were-like distortion, which is superimposed on the light curves, has been obtained. Moreover, small-amplitude light fluctuations in the light curves are noticeable.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
19.
Photometric observation of HR 1099 inV andB obtained on 18 nights between January and March 1977 is presented. The amplitude of the asymmetric light curve is found to be 0m.10±0m.004 both inV andB. On three occasions—namely, JD 2443164. 17, JD 2443176. 14 and JD 2443177.12—the star brightened by 0m.05. Four H spectrograms at 42 Å mm–1 dispersion were obtained during October–November 1978. The profile and equivalent width of H of 14 November, 1978 suggest a probable major outburst.Analysis of all available photometry shows that (1) the amplitude and shape of the light curve change in a few orbital periods, (2) the phase of the minimum light migrated towards decreasing orbital phase during the interval JD 2442720 to JD 2443000 and from JD 2443200, there is almost a linear increase of the phase of the minimum light and (3) the phase of the light minimum sometimes shows to and fro behaviour suggesting the migration of the wave is not taking place smoothly. 相似文献
20.
The light curve andU, B andV observations of the system XY Cep have been presented. Photoelectric and absolute elements of the system have been determined. It is a semi-detached system. 相似文献