• 천문학회지
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• 제48권2호
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• pp.105-112
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• 2015

The symbiotic star V1016 Cygni, a detached binary system consisting of a hot white dwarf and a mass-losing Mira variable, shows very broad emission features at around 6825 Å and 7082 Å, which are Raman scattered O vi λλ 1032, 1038 by atomic hydrogen. In the high resolution spectrum of V1016 Cyg obtained with the Bohyunsan Optical Echelle Spectrograph these broad features exhibit double peak profiles with the red peak stronger than the blue counterpart. However, their profiles differ in such a way that the blue peak of the 7082 feature is relatively weaker than the 6825 counterpart when the two Raman features are normalized to exhibit an equal red peak strength in the Doppler factor space. Assuming that an accretion flow around the white dwarf is responsible for the double peak profiles, we attribute this disparity in the profiles to the local variation of the flux ratio of O vi λλ 1032, 1038 in the accretion flow. A Monte Carlo technique is adopted to provide emissivity maps showing the local emissivity of O vi λ1032 and O vi λ1038 in the vicinity of the white dwarf. We also present a map indicating the differing flux ratios of O vi λλ 1032 and 1038. Our result shows that the flux ratio reaches its maximum of 2 in the emission region responsible for the central trough of the Raman feature and that the flux ratio in the inner red emission region is almost 1. The blue emission region and the outer red emission region exhibit an intermediate ratio around 1.5. We conclude that the disparity in the profiles of the two Raman O vi features strongly implies accretion flow around the white dwarf, which is azimuthally asymmetric.

• 천문학회보
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• 제36권2호
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• pp.147.2-147.2
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• 2011

We have initiated a long-term identification campaign of supernova remnant candidates in X-ray regime. In the short-listed unidentified sources from the ROSAT All Sky Survey, we have chosen the brightest candidate, G308.3-1.4, as our pilot target for a dedicated investigation with Chandra X-ray Observatory. Our observation has revealed an incomplete shell-like X-ray structure which well-correlated with the radio feature. Together with the spectral properties of a shocked heated plasma, we confirm that G308.3-1.4 is indeed a supernova remnant. A bright X-ray point source which locates close to the remnant center is also uncovered in this observation. Its spectral behavior conform with those observed in a rare class of neutron stars. The properties of its optical/infrared counterpart suggests the evidence for a late-type companion star. Interestingly, possible excesses in B-band and H-alpha have been found which indicate this can be an accretion-powered system. With the further support from the putative periodicity of ~1.4 hrs, this source can possibly provide the direct evidence of a binary system survived in a supernova explosion for the first time.

• 천문학회보
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• 제36권2호
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• pp.141.1-141.1
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• 2011

New CCD BVR light curves of BD And are presented. Our light curves with nearly equal depths for both primary and secondary eclipses show well-defined photometric waves outside eclipse for all of BVR bandpasses. The orbital period is greatly revised as $0.^d92580519$ which is twice longer than that known previously. Sixteen timings from our observations and thirteen ones from the SuperWASP measurements were calculated. All available timings over 76 years, including ours, were analyzed to figure out the dynamical behavior of the system. It was found that the recent CCD O-C residuals varied in a cyclical way with a period of $9.^y18$ and a semi-amplitude of $0.^d0046$. The secondary period of $9.^y18$ is the most shortest one among those which have been ever found in the short period RS CVn binary stars. The periodic variation most likely arises from the light-travel time effect due to a low-mass ($m_3{\sim}0.88\;M_{\odot}$) tertiary companion moving in an orbit with an large eccentricity ($e_3$=0.70) and a low inclination ($i_3{\sim}28^{\circ}$). The Applegate mechanism could not operate properly in both components because the model parameters require too much large luminosity changes of ${\Delta}L/L_{p,s}$ > 10. The new light curves were synthesized using the 2003 version of Wilson-Divinney code. It was found useful to model two huge spots on the surface of the hotter star and a third-light in order to minimize the residuals from the observations. Astronomical basic parameters were deduced from our photometric solution.

• Journal of Astronomy and Space Sciences
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• 제9권1호
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• pp.41-51
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• 1992

근접쌍성 AO Can과 AW Cam을 1984년의 관측 계절에 소백산 천문대의 61cm 반사 망원경으로 광전 관측하였다. 이 두별의 관측으로 부터 AO Cam의 채 1 극심시각 l개와 AW Cam익 체 1 극심시각 3 개를 각각 구하였다. 여러 문헌으로 부터 수집한 이 두 별의 극심시각들을 이용하여 최소자송법으로 A0 Cam파 AW Cam의 새로운 광도요소를 구하였다. AO Cam의 공전주기는 1980년 10월(JD 2444520) 부터 1985년 2월 (JD 2446107)까지 일정하였다. 그러나 최근에 Mullis와 Faulkner (1991)가 발표한 AO Cam의 l개의 제2극심시각 (JD 2447864. 7879)은 우리가 새로 구한 광도요소와 약 +4.6분 ( (0.0032일)의 큰 차이가 난다. AO Carn의 극심시각의 앞으로의 관측은 이 별의 공전주기 변화 연구에 중요하다. AW Cam의 공전주기는 지난 1930년대 초 이래 현재짜지 약 60년 동안 P=$0^d.77134645$로 일정하다

• 비교문화연구
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• 제36권
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• pp.123-147
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• 2014

The purpose of this essay is three-fold: to trace the genealogy of the Korean musical, which ever since its inception in the 1960s has been seeking to modernize Korean theater with Broadway as a constant role model; to investigate how the national and the global conflict and are conflated in the form of the Korean musical in the process of its (dis)identification with Broadway; and to examine how its intercultural translations reveal and reflect the dilemma and ambivalence posed by globalization in our era. Drawing on Richard Dyer's signature article Entertainment and Utopia, I analyze how the Korean musical manifests and conduits competing utopian impulses of Korean/Global audiences. I also attempt to problematize the formulaic notion of Broadway musicalsthe Superior Other!which implies a global hegemony that does not, in fact, exist because the boundary between the global and the local as well as the power dynamics of global culture are not fixed but constantly moving and changing. Today's musical scene in Korea shows interesting reversals from the 1990s, when Korean producers were eager to debut on Broadway and impress American audiences. Korean producers no longer look up to Broadway as a final destination; instead they want to make Seoul a new Broadway. They import Broadway musicals and turn them into Korean shows. The glamor of Broadway is no longer the main attraction of musicals in Korea. What young audiences look for most is the glamor of K-pop idols and utopian feelings of abundance, energy, intensity, transparency and community, which they can experience live in the musical with their favorite stars right in front of their eyes. In conclusion, I delve into the complex dynamics of recent Korean musicals with Thomas Friedman's theory of Globalization 3.0 as reference. The binary formula of Global/America versus Local/Korea cannot be applied to the dynamic and intercultural musical scene of today. Globalization is not a uniform phenomenon but rather a twofold (multifold) process of global domination and dissemination, in which the global and the local conflict and are conflated constantly. As this study tries to illuminate, the Korean musical has evolved in a huge net of interdependences between the global and the local with a range of sources, powers and influences.

• 천문학회보
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• 제46권2호
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• pp.50.3-51
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• 2021

The progenitor of Type Ia supernovae is largely expected as a close binary system of a carbon/oxygen white dwarf (WD) primary and its secondary non-degenerate (single degenerate; SD) or degenerate companion (double degenerate; DD). Here we present a high-cadence monitoring observation of SN 2021hpr in a spiral galaxy, NGC 3147. SN 2021hpr shows typical characteristics as a normal type Ia supernova from its photometric (Δm₁₅(B)=1.01±0.03, dust free M_B,max=-19.45±0.02) and spectroscopic data. To investigate its progenitor system, we fit the early part of BVRI-band light curve simultaneously with a combined version of ejecta-companion and simple power-law model. As a result, we found a significant feature of an early excess possibly from a 7.63±0.52R_⊙-sized companion at the optimal viewing angle while the fit is not successful at the common viewing angle. No possible red sources brighter than F555W=-7.01 AB mag is detected at the SN location in Hubble Space Telescope (HST) pre-explosion images, excluding massive stars with initial mass of >16M_⊙ as companions. We suggest the progenitor system of SN 2021hpr can be a fairly large companion such as a main sequence, a low mass subgiant, and a helium giant star. In addition, a possibility of the ejecta-Disk Originated Matter (DOM) interaction for the DD scenario considering linearly-rising early flux still remains.

• Journal of Astronomy and Space Sciences
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• 제22권2호
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• pp.113-124
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• 2005

두개의 식쌍성 V343 Aql 와 CX Aqr 의 가능한 모든 극심시각을 수집하여 두별의 공전 주기변화를 연구하였다 . 그 결과 두 별의 공전주기는 모두 포물선 모양의 영년 변화 위에 주기적인 항이 겹쳐 변화한다. V343 Aql 은 $-261{\times}10^{-7}$ d/y의 영년 주기감소를, 반면 CX Aqr 은 $+2.55{\times}10^{-8}$d/y의 영년 주기증가를 보인다. 두 별의 영년 주기변화의 가능한 원인들에 대하여 논의하였다. 공전주기의 주기적인 변화의 원인을 제3천체에 의한 광시간 효과로 해석하였다. 광시간 궤도의 주기, 반 진폭과 이심율은 V343 Aql인 경우, 각각 30.3 년, 0.0092 일, 그리고 0.85이며, 반면 CX Aqr인 경우, 각각 33.0년, 0.0037일, 그리고 0.64으로 계산되었다. V343 Aql 와 CX Aqr계에 제안된 제3천체의 성질들이 논의된다.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.89-96
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• 2010

BVR CCD observations of GW Cep were made on 15 nights in November through December 2008 with a 1-m reflector at the Jincheon station of the Chungbuk National University Observatory. Nineteen new times of minimum lights for GW Cep were determined and added to a collection of all other times of minima available to us. These data were then intensively analyzed, by reference to an O-C diagram, to deduce the general form of period variation for GW Cep. It was found that the O-C diagram could be interpreted as presenting two different forms of period change: an exclusively quasi-sinusoidal change with a period of 32.6 years and an eccentricity of 0.10; and a quasi-sinusoidal change with a period of 46.2 years and an eccentricity of 0.36 superposed on an upward parabola. Although a final conclusion is somewhat premature at present, the latter seems more plausible because late-type contact binaries allow an inter-exchange of both energy and mass between the component stars. The quasi-sinusoidal characteristics were interpreted in terms of a light-time effect due to an unseen tertiary component. The minimum masses of the tertiary component for both cases were calculated to be nearly the same as the $0.23-0.26M\;{\odot}$-ranges which is hardly detectable in a light curve synthesis. The upward parabolic O-C diagram corresponding to a secular period increase of about $4.12{\times}10^{-8}\;d/yr$ was interpreted as mass being transferred from the lesser to more massive component. The transfer rate for a conservative case was calculated to be about $2.66\;{\times}\;10^{-8}\;M_{\odot}/yr$ which is compatible with other W UMa-type contact binaries.

• 디지털융복합연구
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• 제9권3호
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• pp.69-79
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• 2011

본 연구는 3개 특정공동체에 대하여 미디어에서 정책적으로 의제설정(agenda setting)되었던 텍스트담론을 중심으로 의미작용(signification)의 기호학적(semiotics)분석이다. 연구대상의 자료는 잡지와 전문지, 신문 33개 매체에 게재된 칼럼(column), 특별기고, 시사평론 등 71개의 텍스트담론이다. 연구는 부가의미로 볼 수 있는 은유(metaphor)와 환유(metonymy), 그리고 이분적(binary oppositions)사고 전환( transposition)에 보다 관심을 둔다. 이런 함축적 부가의미는 여러 미디어를 통하여 대중 속으로 내파(imploded)되어 현실보다 더 실재적인 과실재성(hyperreality)으로 신화(myth)를 창출한다. 따라서 본 연구는 미디어가 정책적으로 만들어낸 텍스트담론을 기호학적 시각에서 해체와 분석할 수 있는 이론적 논리를 개발하고자 한다. 또한 기호학의 경계점에서 문화흐름이 정치, 사회, 그리고 경제 등 정책에 어떤 영향을 주는가를 연구할 수 있는 범위를 확장하는 데 있다. 결과적으로 본 연구에서 대상체(referent) 인 T'PALACE, I'PARK, STARCITY가 지시하는 객관적 외시적의미(denotation)는 기존 타 커뮤니티보다 '규모가 크고', '높은 고층이고', '주로 학력 높은 부자들이나 재벌들', 그리고 '연예인들이나 성공한 CEO들'이 거주한 것으로 알려진 외시적의미를 갖는다. 그리고 공동체의 대상체가 지시하는 주관적인 다의적 함축의미(connoation) '귀족커뮤니티', '초호판극치 공간', '양재천의 꽃', '그들만의 공간' 등 은유적 표현은 '대한민국 부 1번지', '벤치마킹대상', '고급주거형태 견본', '국내최고급아파트', '대한민국강남특별시', '1%의 욕망', 등과 같은 환유적 전환의 함축의미로 신화와 이데올로기를 창조하고 있다. 이런 이데올로기와 신화는 미디어를 통해 대중속으로 내파되어(imploded)어 타 지역에서 동일의 이름을 가진 공동체 커뮤니티로 재생산되어 소비(분양)되고 있다. 또한 경제, 문화가 정책이나 정치적으로 활용되어 '종부세', '부자감세', '1%의 부자감세' 등과 같은 정부규정이나 슬로건을 창조하고 있다.