• 천문학회보
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• 제39권2호
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• pp.83.1-83.1
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• 2014

Kepler-47 is the first multi-body circumbinary planetary system detected by the Kepler space telescope. The two planets were detected by the transit method. In the discovery paper the authors report about the presence of an additional transit-like signal in their dataset which cannot be explained by a four-body (binary + 2 planets) system. Therefore it is likely that the unexplained signal could be due to a third planet. In this talk I will present recent results from a dynamical investigation of the five-body system (binary + 3 planets). We have applied the MEGNO technique to detect regions of quasi- or near quasi-periodic orbits of a hypothetical third planet. Quasi-periodic regions exists for a third planet and the long-term stability has been tested. Although the existence of a third planet is most likely to be confirmed from transit photometry we calculate transit-timing variation (TTV) signals due to the third planet which also can be used to infer its presence.

• 천문학회보
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• 제35권2호
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• pp.78.1-78.1
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• 2010

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 13 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 12 elements, such as Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni by EW measurements, and the S abundances were estimated using synthetic spectrum.

• 천문학회지
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• 제44권4호
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• pp.109-113
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• 2011

In current microlensing planet searches that are being carried out in a survey/follow-up mode, the most important targets for follow-up observations are lensing events with high magnifications resulting from the very close approach of background source stars to the lens. In this paper, we investigate the dependence of the sensitivity to planets on detailed properties of high-magnification events. From this, it is found that the sensitivity does not monotonically increase as the impact parameter between the lens and the source trajectory decreases. Instead, it is roughly the same for events with impact parameters less than a certain threshold value. It is also found that events involving main-sequence source stars are sensitive to planets in a much wider range of separation and mass ratio, than those events involved with giant source stars. Based on these results, we propose observational strategies for maximal planet detections considering the types of telescopes available for follow-up observations.

• 천문학회보
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• 제39권1호
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• pp.81.1-81.1
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• 2014

Kepler-47 is the first multi-body circumbinary planetary system detected by the Kepler space telescope. The two planets were detected by the transit method. In the discovery paper the authors report about the presence of an additional transit-like signal in their dataset which cannot be explained by a four-body (binary + 2 planets) system. Therefore it is likely that the unexplained signal could be due to a third planet. In this talk I will present recent results from a dynamical investigation of the five-body system (binary + 3 planets). We have applied the MEGNO technique to detect regions of quasi- or near quasi-periodic orbits of a hypothetical third planet. Quasi-periodic regions exists for a third planet and the long-term stability has been tested. Although the existence of a third planet is most likely to be confirmed from transit photometry we calculate transit-timing variation (TTV) signals due to the third planet which also can be used to infer its presence.

• 천문학논총
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• 제30권2호
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• pp.289-292
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• 2015

Most of the stars in the Galaxy are in binary systems. Binaries should be possible as the hosting stars of planets. Searching for planetary companions to binaries, especially evolved close binary stars, can provide insight into the formation and the ultimate fate of circumbinary planets and shed light on the late evolution of binary stars. In order to do this, we have chosen some post common envelope binaries including sdB-type eclipsing binaries and detached WD+dM eclipsing binaries as our targets and monitored them for several years. In this paper, we will present some of our new observations and results for three targets, NSVS 07826147, NSVS14256825 and RR Cae.

• 산업진흥연구
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• 제8권4호
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• pp.221-227
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• 2023

본 연구는 고전점성학(Classic Astrology)의 네이티비티(Nativity) 출생차트에서 그 차트를 구성하고 있는 행성들의 기능과 구조를 살펴 네이티비티의 직업적성을 분석하는 연구이다. 즉 출생차트에서 나타나는 직업을 개인의 타고난 직업으로 본다면 사인(Sign, 별자리)과 플래닛(Planets, 행성)의 강약, 애스펙트(행성과의 관계) 등을 통하여 분석한다. 고전점성학(Classic Astrology)의 네이티비티(nativity) 출생차트에서는 직업을 판단할 때 크게 세 개의 플래닛인 금성(♀. Venus). 화성(♂. Mars). 수성(☿. Mercury)에 의하여 결정된다고 보았다. 그러나 현대에 와서 고도로 발전된 지식정보화 사회에서 요 구되는 직업의 다양성에 부합하기 위해서는 조금 미흡한 점이 있어 토성(♄. Saturn), 목성(♃. Jupiter), 태양(☉. Sol), 달(☽. Luna)을 더하여 직업의 적성을 적용하였다. 그 결과로 네이티브의 ASC의 직업적성을 플래닛과 그들의 애스펙트 관계를 토대로 더욱 다양하고 폭넓은 적용이 가능하였다. 그 결과 금성(♀. Venus)은 사람들이 아름답다고 생각하는 예술성이 있는 일을 즐기며 그것을 삶의 낙으로 삼을 수 있는 일을 의미하였으며, 화성(♂. Mars)은 노동일과 같이 체력과 힘을 쓰는 일을 의미한 것을 알 수 있었다. 또 수성(☿. Mercury)은 지식과 두뇌를 활용하는 일을 의미하고 있으며, 태양(☉. Sol)은 직업과 재능에 권위를 부여해주는 역할을 하고 있고, 달(☽. Luna)은 네이티브의 직업과 재능에 사람들의 신뢰를 얻도록 해주었으며 목성(♃. Jupiter)은 믿음과 성실함, 공정함, 너그러움 등이 네이티브의 직업과 재능을 살리는데 도움을 주었으며, 토성(♄. Saturn)은 탐욕, 슬픔, 궁핍함 등으로 직업과 재능을 가로막는 장애로 나타날 수 있었고. 결과적으로 플래닛의 강약과 그 플래닛들의 애스펙트 관계에 따라 네이티브의 직업이 다양하게 나타남을 알 수 있었다.

• 천문학회지
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• 제25권2호
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• pp.105-109
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• 1992

We show that spacing patterns of planets and satellites in the solar system are formulatable in a single form. It is suggested that a possible explanation for the rule might be the orbital resonance effect, which has existed at an earlier epoch of the solar (planet) system. By extrapolating the formulated spacing patterns beyond the sun-Pluto distance, we find the sun-Planet X distance falls in a range ($46{\sim}79$) A. U..

• 천문학회보
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• 제46권1호
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• pp.49.1-49.1
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• 2021

SomangNet team aims to make use of small- to medium-sized telescopes for photometric follow-up observations of transiting extrasolar planets orbiting a bright host star. Newly discovered transiting planets need frequent monitoring in order to maintain knowledge of the transit ephemeris. DOAO 1.0 m telescope and CBNUO 0.6 m telescopes are used for our monitoring. We will present some preliminary results of our observations and analysis.

• Journal of Astronomy and Space Sciences
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• 제31권1호
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• pp.7-13
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• 2014

Variabilities in the solar wind cause disturbances throughout the heliosphere on all temporal and spatial scales, which leads to changeable space weather. As a view of space weather forecasting, in particular, it is important to know direct and indirect causes modulating the space environment near the Earth in advance. Recently, there are discussions on a role of the interaction of the solar wind with Mercury in affecting the solar wind velocity in the Earth's neighborhood during its inferior conjunctions. In this study we investigate a question of whether other parameters describing the space environment near the Earth are modulated by the inner planets' wake, by examining whether the interplanetary magnetic field and the proton density in the solar wind observed by the Advanced Composition Explorer (ACE) spacecraft, and the geomagnetic field via the Dst index and Auroral Electrojet index (AE index) are dependent upon the relative position of the inner planets. We find there are indeed apparent variations. For example, the mean variations of the geomagnetic fields measured in the Earth's neighborhood apparently have varied with a timescale of about 10 to 25 days. Those variations in the parameters we have studied, however, turn out to be a part of random fluctuations and have nothing to do with the relative position of inner planets. Moreover, it is found that variations of the proton density in the solar wind, the Dst index, and the AE index are distributed with the Gaussian distribution. Finally, we point out that some of properties in the behavior of the random fluctuation are to be studied.

• Journal of Astronomy and Space Sciences
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• 제19권3호
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• pp.181-186
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• 2002

We study a role of the proto-accretion disk during the formation of the planetary system, which is motivated with recent X-ray observations. There is an observational correlation of the mass of extrasolar planets with their orbital period, which also shows the minimum orbital period. This is insufficiently accounted for by the selection effect alone. Besides, most of planetary formation theories predict the lower limit of semimajor axes of the planetary orbits around 0.01 AU. While the migration theory involving the accretion disk is the most favorable theory, it causes too fast migration and requires the braking mechanism to halt the planet~0.01 AU. The induced gap in the accretion disk due to the planet and/or the truncated disk are desperately required to stop the planet. We explore the planetary evaporation in the accretion disk as another possible scenario to explain the observational lack of massive close-in planets. We calculate the location where the planet is evaporated when the mass and the radius of the planet are given, and find that the evaporation location is approximately proportional to the mass of the planet as ${m_p}^{-1.3}$ and the radius of the planet as ${r_p}^{1.3}$. Therefore, we conclude that even the standard cool accretion disk becomes marginally hot to make the small planet evaporate at~0.01 AU. We discuss other auxiliary mechanisms which may provide the accretion disk with extra heats other than the viscous friction, which may consequently make a larger planet evaporate.