• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.261-268
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• 2003

CCD observations of times of minimum light of IQ Per with apsidal motion were made in VR bandpasses for four nights from November to December, 2002. From the observations four times of minimum light were determined. All times of minimum light collected from literatures, including ours, were analyzed to determine the apsidal motion parameters of IQ per. The sidereal and apsidal motion periods were calculated to be $0.^{s}035$ and $0.^{y}2$ slightly longer than those of Degirmenci (1997), respectively. The apsidal motion parameters of IQ Per derived in this paper show good agreement with Degirmenci's values. Our results support his internal density constant of $k_{2obs}$ = 0.0038 for IQ Per and 5 % accuracy of agreement between the observed and modelled values of the apsidal motion constant.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.341-348
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• 2015

New observations for the times of minimum lights of a well-known apsidal motion star CW Cephei were made using a 0.6 m wide field telescope at Jincheon station of Chungbuk National University Observatory, Korea during the 2015 observational season. We determined new times of minimum lights from these observations and analyzed O-C diagrams together with collected times of minima to study both the apsidal motion and the Light Time Effect (LTE) suggested in the system. The new periods of the apsidal motion and the LTE were calculated as 46.6 and 39.3 years, respectively, which were similar but improved accuracy than earlier ones investigated by Han et al. (2002), Erdem et al. (2004) and Wolf et al. (2006).

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.42.1-42.1
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• 2016

We examined thousands of light curves of stars brighter than 18.0 mag in I band and less than mean magnitude error of 0.1 mag in V band from the OGLE-III eclipsing binary catalogue, and found 90 new binary systems exhibiting apsidal motion. In this study, the samples of apsidal motion stars in the SMC were increased by 250 percent than previously known. In order to determine the period of the apsidal motion for the binaries, we analysed in detail both light curves and eclipse timings using the MACHO and OGLE photometric database obtained for about 20 yrs. For the eclipse timing diagrams of the systems, new times of minimum light were derived from the full light curve combined at intervals of one yr from the survey data. The binaries presented in this paper have apsidal motion periods in the range of 12-918 yrs. An additional short-term oscillation was detected in five systems (OGLE-SMC-ECL-1634, 1947, 3035, 4946, and 5382), which most likely arise from the existence of a third body orbiting each eclipsing binary. All of the selected systems can be used for the statistical study of the interior structure of the stars in the SMC through their apsidal motions due to the homogeneous data and consistent analysis methods.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.211-214
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• 2015

We investigated the period variation for 79 eclipsing binary systems using 20 years (1990-2009) of EROS, Macho, and OGLE survey observations. We discovered 9 apsidal motions, 8 mass transfers, 5 period increasing and decreasing systems, 12 light-travel-time effects, 5 eccentric systems and 40 other systems showing no period variations. We select 3 representative eclipsing binary systems; EROS 1052 for apsidal motion, EROS 1056 for mass transfer, and EROS 1037 for the light-travel-time effect. We determine the period variation rate (dP/dt), orbital parameters of the 3rd body (e3, ${\omega}_3$, $f(m_3)$, $P_3$, $T_3$), apsidal motion parameters ($d{\omega}/dt$, U, Ps, Pa, e) and apsidal motion period by analyzing the light curves and O-C diagrams.

• Journal of Astronomy and Space Sciences
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• v.1 no.1
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• pp.41-53
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• 1984

Photoelectric observations of the close eclipsing binary system CW Cep, which is well known of its apsidal motion, were made on 20 nights during August and November in 1983 using two 61cm reflectors at the Sobaeksan Observing Station of Korean National Astronomical Observatory and I1san Observing Station of Yonsei University Observatory. Standardized new light curves in UBV system are presented with a total of 1,422 individual observations. For the corrections of regional and instrumental differences, same standard stars were observed at the two observatories. Four new times of minimum light were determined with the method of Kwee and van Woerden(1956). With all of the collected times of minima, apsidal motion of this system was checked, but the O-C values calculated by the light elements of Nha(1975) and Soderhjelm (1976) did not coincide well with new times of minima. New light elements which satisfy most times of minima better, and are deduced the apsidal period derived by the new light elements turns out to be 43 years, somewhat longer than those of values previously known.

• The Bulletin of The Korean Astronomical Society
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• v.7
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• pp.4.1-4.1
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• 1982

• Journal of Astronomy and Space Sciences
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• v.13 no.1
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• pp.63-71
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• 1996

A total of 546 UBV photoelectric observations of AG Per was carried out from January to December in 1993 at Chungbuk National University Observatory. With our observations, UBV light curves were constructed, three minimum times of JDHel. 2449284.213, JDHel. 2449360.060, and JDHel. 2449363.192 were determined. The phase displacement of secondary minimum time $\delta$=-0.046 were determined and orbital eccentricity e=0.071 was calculated. Forty-five times of minimum light (including ours) were collected from the literature and plotted on O-C diagram. We analyzed these data and apsidal motion period of U=76.17 (years) was obtained. Using e and U for AG Per, the internal structure constant, log k2, was found to be -2.13.

• Bulletin of the Korean Space Science Society
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• 1996.05a
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• pp.23-23
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• 1996

No Abstract, See Full Text

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.38.3-38.3
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• 2008

In There are inventoried 308 eclipsing systems among 1,158 multiple systems listed in Tokovinin (1997, 2007)'s multiple system catalog. Their characteristics of (O-C) variations for 83 systems among the 308 systems, which have timings of minimum lights enough to see the trends of their period changes, were investigated with the Kreiner, Kim and Nha (2001)'s recent database of times of minimum lights of eclipsing binaries. It is found that the (O-C) variations for 39 systems, corresponding to 47% of the investigated 83 systems, does not show any anticipated light-time effects (hereafter LITE) at all. Among the rest 44 systems 7 systems with apsidal motion also have a single LITE. Only 6 systems have a single LITE or double LITEs. The rest 31 systems show a secular variation superposed on a single or double or more LITEs or very complicated variation patterns. Some possible explanations for their diverse differentiation of variation are discussed.