• Journal of Astronomy and Space Sciences
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• 제3권1호
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• pp.1-13
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• 1986

A long-term project(ten-year ; 1982-92) for the photoeletric observation in the UBV passbands of selected eclipsing binaries with P$\geq$10 days has initiated at Yonsei University Observatory using 40-cm and 61-cm reflectors. the instrumentatio used and the observation techniques and the reduction procedures applied to this investiagation are described. Out of 39 program stars, successful results have been obtained during our first two years for the 11 stars listed below, with the orbital period in days in the parenthesis, and the incomplete light curves of these stars are presented. SX Cas (36.57) AQ Cas (11.72) UU Cnc (96.71) RY Gem (9.30) V373 Cas (13.42) NY Cep (15.28) RX Cas (32.32) V396 Cas (15.28) ZZ Cnc (25.60) Zet Aur (982.2) Eps Aur (9885.) For the rest of the stars, the observations made in the first two years are not sufficient to attempt any meaning light curve construction ; some of the data are too fragmented and others show large scatter.

• 천문학회보
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• 제41권1호
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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.

• 천문학논총
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• 제30권2호
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• pp.231-232
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• 2015

R Canis Majoris is a bright, short-period ($1^d$.1359) Algol-type eclipsing binary. For a long time, it was considered to be a low-mass binary star with $M_1=1.1M_{\odot}$ and $M_2=0.17M_{\odot}$ primary and secondary components, respectively (Tomkin, 1985). Glazunova, Yushchenko & Mkrtichian (2009) found new masses for the primary and secondary components of $M_1=1.81M_{\odot}$ and $M_2=0.23M_{\odot}$, respectively and resolved a long-standing problem with the low masses of components for this binary. Budding and Butland (2011) confirmed the results of Glazunova, Yushchenko & Mkrtichian and obtained improved orbits and masses. New spectroscopic observations of R CMa were done during 8 nights on December 2012 with the 2.4-meter telescope of the Thai National Observatory (TNO) and fibre-fed medium resolution echelle spectrograph. We obtained new, accurate orbital radial velocities of the two components of this binary system. Results of these investigations and the new orbital parameters are presented.

• 천문학회보
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• 제37권2호
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• pp.143.1-143.1
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• 2012

We attempt to investigate the main reason of the asymmetrical light curves of contact and near-contact eclipsing binary base on the hypothesis that cool spot was produced on late type star while hot spot was produced from transferred material from their companion star hitting surface. We select 7 eclipsing binary systems which showed asymmetric light curves and mass transfer. Period variation and mass transfer rate were obtained from O-C diagram. Radial velocity curves and light curves of those 7 eclipsing binary system were adopted from available literature in order to obtain the absolute dimension. For four contact eclipsing binary system (AD Phe, EZ Hya, AG Vir and VW Boo), their component stars belonged to spectral type G to K was fitted by cool spot model. While the other two near-contact systems (RT Scl and V1010 Oph) and one contact system (SV Cen) was fitted by cool spot model. The densities of the materials are adopted from stellar model which calculate by stellar structure code. The calculated spot temperature turns out to agree with the photometric solution but there are no correlate between period variation rate and type of spot.

• 천문학논총
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• 제28권3호
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• pp.83-93
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• 2013

NGC 6871을 중심으로 한 Cyg OB3 성협 영역에 대한 변광성 탐사로부터 Paper I에 이어 27개의 식쌍성과 19개의 장주기형 불규칙 변광성을 찾았다. 이 중에서 5개를 제외한 나머지는 모두 새로 발견한 것이다. 27개의 식쌍성 중에서 20개는 주기와 변광진폭 등을 구하였으며, 나머지 7개는 모두 EA형 식쌍성으로 보이지만 관측자료의 부족으로 주기를 결정하지는 못하였다. 주기를 구한 20개의 식쌍성 중에서 주극소의 깊이를 확실하게 구하지 못한 V27를 제외한 V와 B등급의 변광진폭비 $A_V/A_B$가 0.88로서 Paper I의 ${\delta}$ Scuti형 변광성의 결과를 이용한 0.72와 뚜렷이 구분된다. EW형 식쌍성 만을 이용할 경우 변광진폭비는 0.92로 더 뚜렷이 구분되었다. 19개의 장주기형 불규칙 변광성은 주기가 너무 길고, 또한 비주기성 변광성으로 보이므로 주기를 얻지는 못하고, 밝기 변화만 알 수 있었다. 이 연구에서 찾은 변광성은 V등급이 9.05등급부터 16.47등급까지 분포하며, 변광진폭이 클 경우 16.5등급까지도 변광 여부를 확인할 수 있었다.

• 천문학회지
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• 제55권1호
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• pp.1-9
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• 2022

We present the photometric properties of V608 Cas from detailed studies of light curves and eclipse timings. The light curve synthesis indicates that the eclipsing pair is an overcontact binary with parameters of ∆T = 155 K, q = 0.328, and f = 26%. We detected the third light ℓ₃, which corresponds to about 8% and 5% of the total systemic light in V and R bands, respectively. Including our 6 timing measurements, a total of 38 times of minimum light were used for a period study. It was found that the orbital period of V608 Cas has varied in some combination of an upward parabola and two periodic variations. The continuous period increase with a rate of +3.99 × 10^-7 d yr^-1 can be interpreted as a mass transfer from the secondary component to the primary star at a rate of 1.51 × 10^-7 M_⊙ yr^-1. The periods and semi-amplitudes of the two periodic variations are about P₃ = 16.0 yr and P₄ = 26.3 yr, and K₃ = 0.0341 d and K₄ = 0.0305 d, respectively. The most likely explanation of both cycles is a pair of light-traveling time effects operated by the possible presence of third and fourth components with estimated masses of M₃ = 2.20 M_⊙ and M₄ = 1.27 M_⊙ in eccentric orbits of e₃ = 0.66 and e₄ = 0.52. Because the contribution of ℓ₃ is very low compared to the estimated masses of two circumbinary objects, they can be inferred as very faint compact objects.

• Journal of Astronomy and Space Sciences
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• 제9권1호
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• pp.30-40
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• 1992

세 종류의 식쌍성에 대한 반사 효과를 Wilson과 Devinney의 모델과 Russell과 Merrill의 모델로 분석하였다. 반사 효과를 Wilson과 Devinney의 광도 곡선 프로그램을 이용하여 이론적인 광도 곡선에 여러가지 유형별로 나타내었다. 그후 반사효과가 나타난 이론적인 광도 곡선을 Russell과 Merrill의 방법으로 근접 효과를 보정하여 두 모델을 비교 분석하였다. 두 별의 온도 차이와 반사도의 차이가 작은 경우에만 반사 효과에 관한한 두 모델이 일치함을 보였다.

• Journal of Astronomy and Space Sciences
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• 제10권1호
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• pp.44-85
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• 1993

EA형이며 준분리형에 속하는 19개의 식쌍성에 대한 공전주기 변화를 조사하였다. 그런데 각 식쌍성의 주기 변화각 갑작스러운 주기 변화를 보이는 일차항의 광도요소를 갖는다는 가정하에 주기 변화를 분석하였다. 이러한 분석을 통하여 각 식쌍성의 주기 변화와 그 별의 물리량과의 상관관계를 조사하였다.

• 천문학논총
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• 제22권4호
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• pp.141-149
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• 2007

Preliminary time-series observations for short-period variability survey (SPVS) were carried out using a 155mm refractor and a $2k{\times}3k$ CCD camera at Bohyunsan Optical Astronomy Observatory. We found 21 new variable stars in the $90'{\times}60'$ test field region : 9 eclipsing binary stars, $5{\delta}$ Scuti type stars, a ${\gamma}$ Doradus type star, and 6 long period variables. The observing field center is R.A. $05^h\;00^m\;00^s$, DEC. $50^{\circ}\;00'\;00"$ (J2000.0). The period and amplitude ranges for the short-period variables, i.e., ${\delta}$ Scuti stars, were 0.052day - 0.107day and 0.012mag - 0.064mag, respectively.

• 천문학회지
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• 제45권1호
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• pp.1-6
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• 2012

We use a Probabilistic Neural Network (PNN) technique to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of five double-lined spectroscopic binary systems (i.e., EQ Tau, V376 And, V776 Cas, V2377 Oph and EE Cet), we find the corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by other groups via more traditional methods.