• Journal of Astronomy and Space Sciences
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• 제1권1호
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• pp.55-65
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• 1984

A total of 618 photoelectric observations (302 in yellow and 316 in bule) is made in 1982 at the Yonsei University Observatory. Except that of the secondary eclipse the homogeneous coverage of observations successfully secured B, V, and B-V light curves. Enhanced distortions in the light curves are appeared at the phases aroung $0.^P1$, which supports the wave-like migration period of 9.7 years(Rodono 1981). One epoch time of the primary minimum was made by combining the observations in three nights. This minimum time shows that the O-C values are still decreasing and there seems to indication of increasing. B and V light curves of the primary minimum are in strong asymmetry which show less luminous in the third and fourth contacts compared to those of the first and second ones. This asymmetry may be as a result of the reflection of the wave minimum at $0.^P1$, and B-V curve also shows asymmetry, redder at the third contact than the second one by about $0.^m04$. This color difference apperature distribution on the surface of cooler, larger component(KO IV star).

• Journal of Astronomy and Space Sciences
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• 제2권1호
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• pp.35-45
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• 1985

Standardized B and V photoelectric light curves of Algol are made with the obsevations obtained during 1982-84 with the 40-cm and the 61-cm reflectors of Yonsei University Observatory. These light curves show asymmetry between ascending and descending shoulders. The ascending shoulder is 0.02 mag brighter than descending shoulder in V light curve and 0.03mag in B light curve. These asymmetric light crves are interpreted as the result of inhomogeneous energy distribution on the surface of one star of the eclipsing pair rather than the result of gaseous stream flowing from KOIV to B8V star. The 180-year periodicity, so called great inequality, are most likely the result proposed by Kim et al.(1983) that the abrupt and discrete mass losses of cooler component may be the cause of this orbital change. The amount of mass loss deduced from these discrete period changes turned out to be of the order of $10^{-6}$ - $10^{-5}M_\odot$.

• Journal of Astronomy and Space Sciences
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• 제5권1호
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• pp.9-18
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• 1988

연세대학교 천문대에서 1983~1987 기간에 Be 성 $\gamma$ Cas을 총 31일 밤 광전측광관측을 하여 312개의 UBV관측점을 얻었다. 우리가 얻은 자료 중에서 비교적 관측시간이 길었던 5일분의 자료로, V, B-V, U-B광도 곡선을 만들었고, $\gamma$Case 의 일반적인 측광학적 특성을, V/R번화와 최근 IUE 인공위성관측에서 나타난 high velocity narrow component(hvnc)의 시기와 관련시켜 검토하였다. 또한, $\epsilon$ Per는 $H\beta$선의 모양(line, profile)이 심하게 변하는 이색적인 B형 별인데, 우리는 1984년에 IUE인공위성에서 관측한 이 별의 스펙트럼 image data 6개조를 분석하여 $H\beta$선에서와 같은 흡수선의 모양 변화가 UV영역의 SiIVsk CIV선에서도 일어나고 있는지를 비교검토한 결과, 이 6개 자료에서는 어떤 변화도 발견하지 못했다.

• 천문학회지
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• 제28권1호
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• pp.31-43
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• 1995

We present UBVRI CCD photometry of the Type Ie supernova SN 19941 in M51 which was discovered on April 2, 1994 (UT). UBVRI CCD photometry of SN 1994 I were obtained for the period of the first two months from April 4, 1994, using the Seoul National University Observatory 60 cm telescope. The light curves of SN 19941 show several interesting features: (a) SN 19941 reaches the maximum brightness at B-band on April 8.23 (B = 13.68 mag), at V-band on April 9.10 (V = 12.89 mag), and at I-band on April 10.32 (I = 12.48 mag); (b) The light curves around the maximum brightness are much narrower than those of other types of supernovae; (c) The light curves after the peak decline more steeply than those of other types of supernovae; and (d) The colors get redder from $(V-R){\approx}0.2 mag ((V - I){\approx} 0.3 mag, (B - V){\approx}0.7 mag)$ on April 4 to $(V-R){\approx}0.6 mag ((V-1){\approx}0.9 mag, (B-V){\approx}1.3 mag)$ on April 18. Afterwards (V - R) colors get bluer slightly $(by\~0.005 mag/day)$, while (V-I) colors stay almost constant around $(V-1){\approx}1.0 mag$. The color at the maximum brightness is (B-V)=0.9 mag, which is $\~1$mag redder than the mean color of typical Type la supernovae at the maximum brightness. The light curves of SN 1994I are similar to those of the Type Ie supernova SN 1962L in NGC 1073. Adopting the distance modulus of $(m-M)_0 = 29.2 mag$ and the reddening of E(B - V) = 0.45 mag [Iwamoto et al. 1994, preprint for ApJ], we derive absolute magnitudes at the maximum brightness of SN 1994I, Mv(max) = -17.7 mag and MB(max) = -17.4 mag. This result shows that SN 1994I was $\~2$mag fainter at the maximum brightness compared with typical Type Ia supernovae. A narrower peak and faster decline after the maximum in the light curve of SN 1994I compared with other types of supernovae indicate that the progenitor of SN 1994I might be a lower mass star compared with those of other types of supernovae.

• Journal of Astronomy and Space Sciences
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• 제8권2호
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• pp.149-158
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• 1991

Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1) The light variation outside eclipse follow none of the wave migration patterns reported by previous investigators. (2) Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests than, in the future, AR Lac has a chance to attain a normal state with no complicated interactions. (3) The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4) The K0 star, the larger component, has brightened by $0.^m$ 14 in V, while the G2 star has shown a fluctuation of about $0.^m$05 in V. (5) The B-V values at primary mid-eclipse have no correlation with the depth variations. (6) Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

• 천문학회지
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• 제7권1호
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• pp.16-18
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• 1974

Photolectric observations with B and V filters of the eclipsing binary system V448 Monocerotis are presented. The light curves, which cover 30% of the light cycle, show the variability of this system.

• Journal of Astronomy and Space Sciences
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• 제23권3호
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• pp.177-188
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• 2006

소백산 천문대의 61cm 망원경과 2K CCD 카메라로 2003년 1월 6일부터 24일까지 5일간 WUMa형 접촉쌍성 V523 Cas를 측광판측하여 총 920개의 관측점(${\Delta}B$: 230점, ${\Delta}V$. 230점, ${\Delta}R$: 230점, ${\Delta}I$: 230점)을 얻었다. 우리의 관측점으로부터 9개의 새로운 극심시각(주극심: 5개, 부극심: 4개)을 산출하였다. 2004년도 Wilson-Devinney(WD) 쌍성 모형으로 우리가 얻은 새로운 BVRI 광도곡선과 Rucinski et al.(2003)의 시선속도 곡선을 결합하여 분석함으로서 V523 Cas의 제 물리요소를 새롭게 산출하였다. 광도곡선에 나타난 작은 비대칭을 온도가 높은 주성의 광구 표면에 차거운 흑점과 반성에 뜨거운 흑점을 가정하여 설명하였다.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.1-8
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• 2009

질량비가 작은 접촉쌍성 FP Boo를 3색(B, V, R) CCD 측광관측하여 새로운 광도곡선을 얻었으며, Rucinski et al.(2005)의 시선속도곡선과 함께 Wilson-Devinney 프로그램에 적용하여 FP Boo의 새로운 측광학적 해와 절대물리량을 구하였다. FP Boo를 포함한 24개의 질량비가 작은 접촉쌍성의 H-R도로부터 FP Boo의 진화 상태도 일반적인 질량비가 작은 접촉쌍성의 진화 상태와 일치하는 위치에 놓이고 있음을 다시 확인하였다. 이번 관측을 통하여 얻은 우리의 광도곡선에서는 작지만 약간의 비대칭성을 보였다.

• Journal of Astronomy and Space Sciences
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• 제11권1호
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• pp.21-30
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• 1994

VV Cep-type long period spectroscopic-eclipsing binary AZ Cas has been observed for five years, 1985 Oct~1990 Feb, UBV at the Ilsan Station of Yonsei University Observatory. A total of 431 observations (U=129, B=142 and V=160) are made for 86 nights. Instrumental differential UBV and B-V light curves made with these observations cover phases nearly a half of one period. There is no appreciable light variation in V but in other two passbands a gradual decrease of the brightness is clearly noticed. The loss of light in B resulted in a reddening in $\Delta(B-V)$ by + 0.06 at phases between 0.4~0.5 as compared with that of at phase ~0.1. This intrinsic reddening arouses a question why at the orbital phase of the transit of a hot star in front of a cool M supergiant the heating of the facing hemisphere of M supergiant by the strong radiation from the B stat is absent. With regard to this unusual situation we propose a hypothesis that a large amount of gas stream of low temperature ejected from the surface of M supergiant component towards the B star dominates the brightness of B star and the reflection effect.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.263-272
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• 2002

보현산 천문대의 1.8m 망원경을 이용하여 1999년 10월 19일부터 21일까지 총 3일간 W UMa형 접촉쌍성 V523 Cas를 CCD 측광관측하여 총 616 (308의 ${\Delta}$b점, 308의 ${\Delta}$v점) 개의 관측점을 얻었다. 우리의 관측점으로부터 4개의 새로운 극심시각(주극심 2개, 부극심 2개)을 산출하였다. 우리가 얻은 BV 광도곡선과 Milone et al.(1985)의 시선속도곡선을 Wilson-Devinney(WD) 방법으로 흑점이 있는 경우와 없는 경우로 나누어 광도곡선의 해를 산출하였다.