• Journal of Astronomy and Space Sciences
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• 제11권2호
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• pp.196-207
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• 1994

소위 O'Connell효과라고 하는 비대칭 광도곡선을 갖는 27개의 W UMa형 식쌍성들을 수집하고 광도곡선 형태에 다라 12개의 +형과 15개의 -형으로 분류하였다. 이렇게 분류된 별들을 관측된 물리량 사이의 상대적인 상관관계와 진화상태를 조사하였다.

• Journal of Astronomy and Space Sciences
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• 제18권1호
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• pp.55-62
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• 2001

W UMa 형 쌍성 TY UMa를 소백산천문대 61cm 반사망원경과 PM512 CCD 카메라를 이용하여 2001년 3월 19일부터 21일까지 3일간 측광관측하여 광도곡선을 완성하였다. 광도곡선의 형태는 제 2극심이 제 1극심보다 더 깊고, 식 바같부분의 max 1은 max II에 비하여 평균 $0.^m023$밝게 나타나는 비대칭이다. 비대칭 광도곡선을 분석하기 위하여 흑점 모델을 도입하고, Wilson & Devinney의 차등보정법을 이용하여 측광학적인 해를 구하였다.

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.65-68
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• 1998

We construct the X-ray light curves of the W UMa type contact binary SS Arietis(HD12929) from the EXOSAT data in HEASARC data archive. The phase dependent X-ray light curves obtained by using the ephimeris of Kaluzny & Pojmanski of SS Ari is modulated on the orbital phase as in the case of other W UMa type binaries. Although a detailed analysis of these data is impossible because of the very low X-ray light curves in the context of the radiation in the corona region of W UMa type stars.

• Journal of Astronomy and Space Sciences
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• 제17권2호
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• pp.151-162
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• 2000

근접촉쌍성을 분광형에 따라 A형과 F형으로 분류하여 각각의 물리적 특성과 진화를 조사하였다. 그 결과, 근접촉쌍성이 TRO 이론에 따른 진화 경로를 겪는다고 가정하면, F형이 A형에 비하여 더 접촉에 가까운 즉, W UMa형에 근접한 상태에 있을 가능성이 있음을 알 수 있었다. NCBs의 질량-반경 관계, 질량-광도 관계 및 H-R도를 조사하였는데 그 결과 A형이 F형에 비하여 질량교환이 활발할 것으로 생각된다. 근접촉쌍성은 ZAMS와 평행하게 나타나며 접촉쌍성의 진화 위치와 거의 일치하고 있다.

• 천문학회지
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• 제38권2호
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• pp.43-57
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• 2005

The authors have assembled a sample of 80 W UMa binary systems (42 W-subtype and 38 A-subtype) whose light curves have all been solved by means of the recent W-D code and combined with up-to-date radial velocity solutions. The absolute parameters (masses, radii and luminosities) have been derived (without any constraint on the physical parameters). The main results of this paper are: (1) the mass-luminosity relations for both W&A-subtypes. as well as for all W UMa contact binaries have been shown, (2) the mass-radius relations have been found for both subtypes, (3) some remarks on the evolution status have been presented.

• 천문학회보
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• 제26권2호
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• pp.45-45
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• 2001

• Journal of Astronomy and Space Sciences
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• 제23권4호
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• pp.311-318
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• 2006

ROTSE(Robotic Optical Transient Search Experiment) 후속관측을 통하여 W UMa형 식쌍성으로 재분류했던 변광성 중 광도곡선의 형태가 특이한 2개의 변광성에 대하여 2004년 5월 1일부터 5일간에 걸쳐 레몬산천문대 1m 망원경을 이용하여 고정밀 측광관측을 BVI 영역에서 수행하였다. W UMa형 식쌍성의 체계적인 분석을 위하여 2005년 개정한 Wilson-Devinney 쌍성코드를 사용하는 광도곡선분석 스크립트를 작성하였다. GSC2576-0319와 GSC2584-1731의 광도곡선을 분석하여 얻은 궤도경사각 (i)은 $43.^{\circ}5$와 $57.^{\circ}6$로써 비교적 낮은 값을 가지고 있으며, GSC2S84-1731의 광도곡선상 비대칭 효과를 설명하기 위하여 흑점모델을 적용하고, 이때의 흑점인자를 결정하였다.

• 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.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.29.2-29.2
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• 2008

The CCD photometric observations of the W UMa type contact binary GX Aur were performed for 33 nights from 2004 to 2008 using a 2K CCD camera and Johnson BVRI filter system attached to the 61cm reflector at Sobaeksan Optical Astronomy Observatory (SOAO). From our observations, the first BVRI light curves of GX Aur were completed and eight new times of minima (primary: 4, secondary: 4) were obtained. All the times of minima including our timings were collected and analyzed to see the dynamical behavior of GX Aur system. Intensive analysis of our BVRI lightcurves with the recent Wilson-Devinney binary model shows that GX Aur is an over-contact binary whose component stars have equal mass and time-variable spots.

• 천문학회지
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• 제43권6호
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• pp.201-211
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• 2010

We present an analysis of the measurements of mid-eclipse times of V839 Oph, collected from literature sources. Our analysis indicates a period increase of $3.2{\times}10^{-7}$ day/yr. This period increase of V839 Oph can be interpreted in terms of mass transfer of rate $1.76{\times}10^{-7}M_{\odot}/yr$, from the less to the more massive component. The O - C diagram shows a damping sine wave covering two different complete cycles of 36.73 yr and 19.93 yr with amplitudes approximately equal to 0.0080 and 0.0043 day, respectively. The third cycle has to be expected to cover about 13.5 years with lower amplitude than those of the former two cycles. These unequal duration cycles show a non periodicity which may be explained as resulting from either the presence of a tertiary component to the system or cyclic magnetic activity variations due to star spots. For the later mechanism, the obtained characteristics are consistent when applying Applegate (1992) mechanism.