• Journal of Astronomy and Space Sciences
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• 제8권2호
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• pp.125-131
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• 1991

UBV observations at Yonsei University Observatory (500 and 537 observations each at Ilsan Station and at Campus Station) were made for the latest eclipse of $\zeta$ Aur in 1987-1988. Orbital period of Saijo and Saito has been confirmed and the light and color variations on the night JD 244730 are found.

• 천문학회지
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• 제2권1호
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• pp.10-22
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• 1969

Two-Color photoelectric observations were made at Flower and Cook Observatory, University of Pennsylvania. Since the spectroscopic elements are available for the system, derivation of an absolute physical dimension is now expected to be feasible. Results of computation of the orbital elements lead to a fact that the system shows an annular eclipse rather than a partial which is a finding reported by Shapley.

• 천문학회보
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• 제25권1호
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• pp.42-42
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• 2000

• 천문학회지
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• 제29권spc1호
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• pp.239-240
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• 1996

Precise masses, radii, and luminosities from eclipsing binaries and colour-magnitude diagrams for open clusters are classic tools in empirical tests of stellar evolution models. We review the accuracy and completeness required for such data to discriminate between current models and describe some recent. results with implications for convection theory.

• Journal of Astronomy and Space Sciences
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• 제15권2호
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• pp.297-306
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• 1998

Photoelectric observations of the neglected eclipsing binary VZ Cep were made on four night during the observing season of 1984 at Sobaeksan Astronomy Observatory. The UBV light curves were secured incompletely with the gap in 0.35-0.75 phases. From the observations three times of minimum lights were determined in three band-passes, which formed one weighted minimum epoch (JD Hel 2446009.0453). With our observations, and improved light elements for VZ Cep is determined using all the photoelectric and CCD times of minimum lights published so far. The (O-C) resid-uals calculated with our light elements show small varying scatters which cannot be negligible. From the analyses of all the times of minima with the Scargle’s(1982)period-searching and a curve fitting methods, we found possible periodic oscillations of the (O-C) residuals with the period of 1. y26 and the amplitude of 0.d0032. These results, however, have to be considered as a preliminary values until complete analysis for the minimum lights of VZ Cep with enough observational data. Future observations of this binary system are urgently prompted.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2003년도 한국우주과학회보 제12권2호
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• pp.75-75
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• 2003

All published and newly observed times of minimum light of the massive, early-type eclipsing binary star AH Cep were analyzed. After subtracting the light time effect due to the well-known third body from the residuals of the observed times of minimum light, it was found that the second-order Ο-C residuals varied in a cyclical way. It was assumed that the secondary oscillations were produced by a light time effect due to a fourth body so all the times of minimum light were reanalyzed with a differential least-squares scheme in order to obtain the light time orbits due to both the third and fourth bodies. The periods, eccentricities, semi-amplitudes of the light time orbits for the third and fourth-bodies were derived as : P$\_$3/=68.$\^$y/3 and P$\_$4/=9.$\^$y/3, e$_3$=0.53 and e$_4$=0.83, K$_3$=0.$\^$d/0585 and K$_4$=0.$\^$d/0045, respectively. The analysis of the radial velocities of AH Cep published so far, do not conflict with the hypothesis of the multiplicity of the system but their accuracies are not high enough to be useful to support the interpretation. Other properties of the distant bodies are discussed for assorted possible inclinations of their orbits.

• Journal of Astronomy and Space Sciences
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• 제26권3호
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• pp.295-304
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• 2009

대마젤란은하 중심부에 위치한 식쌍성 EROS 1010에 대한 CCD 측광관측을 2006년과 2007년에 수행하여 BV 광도곡선을 완성하였다. BV 광도곡선은 EROS팀과 OGLE팀이 각각 관측한 BR과 I 광도곡선과 함께 Wilson & Devinney 차등보정법으로 분석하여 측광학적인 해를 제시하였다. 한편 대마젤란은하의 거리지수를 $m-M=18.^m3{\sim}18.^m5$ 사이로 가정하고, EROS 1010에 대한 절대량을 구하였다.

• 천문학논총
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• 제15권spc1호
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• pp.133-145
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• 2000

Symbiotic stars are known as binary systems with both cool and hot components with enshrounding nebulous gas. The cool component, M-type giant, is presumably loosing its mass into a hot white or main sequence companion star through the inner Lagrangian point. The lines emit from the ionized nebulous region around the hot star while the mass loss or accretion activity is believed to be the main cause of sudden variation of the continuum and line fluxes. We selected 17 symbiotics for which the emission line fluxes were measured from the IUE SWP, LWR data, to find variability of spectrum. We also investigated the periodic variation of emissions or eclipsing effect from the IUE lines. All of our symbiotics show very high electron densities in the emission regions. For other optical symbiotics, the observations had been carried in 1999 with BOAO mid-resolution spectrometer. We classified symbiotics based on their outburst activities, or emission line characteristics, i.e., $OVI{\lambda}6830.\;The\;OVI{\lambda}6830$ emission lines are also found in S-type symbiotics, which have been known as charateristics of D-types.

• 천문학회지
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• 제44권3호
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• pp.97-108
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• 2011

The photometric light curves of the W-type W UMa eclipsing contact binary system BB Pegasi have been found to be extremely asymmetric over all the observed 63 years in all wavelengths UBVR. The light curves have been characterized by occultation primary minima. Hence, the morphology of these light curves has been studied in view of these different asymmetric degrees. The system shows a distinct O'Connell effect, as well as depth variation. A 22.96 years of stellar dark spots cycle has been determined for the system. Almost the same cycle (22.78 yr) has been found for the depth variation of MinI and MinII. We also present an analysis of mid-eclipse time measurements of BB Peg. The analysis indicates a period decrement of $5.62{\times}10^{-8}$ day/yr, which can be interpreted in terms of mass transfer at a rate of $-4.38{\times}10^{-8}M_{\odot}$/yr, from the more to the less massive component. The O - C diagram shows a damping sine wave covering two different cycles of 17.0 yr and 12.87 yr with amplitudes equal to 0.0071 and 0.0013 day, respectively. These unequal durations show a non-periodicity which may be explained as a result of magnetic activity cycling variations due to star spots. The obtained characteristics are consistent with similar chromospherically active stars, when applying the Applegate's (1992) mechanism.

• 천문학논총
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• 제20권1호
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• pp.21-27
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• 2005

We have been performing a wide-field photometric monitoring program, named SPVS (Short-Period Variability Survey), at the Bohyunsan Optical Astronomy Observatory (BOAO). The observation system consists of a small refracting telescope (D = 155 mm, f = 1050 mm) and a $2k{\times}3k$ CCD Camera. The field of view is $1.0^{\circ}{\times}1.5^{\circ}$. Detection limit is about V = 13 for short-period small amplitude variables such as ${\delta}$ Scuti-type pulsating stars, and about V = 15 for long-period large amplitude variables such as eclipsing binaries and RR Lyrae stars. The instrument is designed to be remote-controlled through internet. The primary purpose of this project is to search for variable objects in bright Galactic open clusters. We present results of test observations conducted towards NGC 7092.