• 천문학회보
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• 제40권2호
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• pp.35.4-36
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• 2015

Gaseous inner disks are the main controller of the final structure of planetary systems as well as the building place of planets, especially of terrestrial planets. However, the inner disk of <5AU is still difficult to be spatially resolved even at the closest star forming regions. Resolving velocity structure in the disk with high resolution infrared spectroscopic study is the best approach to study the inner disk at this moment. Here, we present the IGRINS (Immersion GRating INfrared Spectrometer) result of the Class I young stellar object, ESO Ha 279a, in the Serpens molecular cloud region. IGRINS has a resolving power of R=40,000, corresponding to the velocity resolution of 7 km/s at K-band, which is perfect to study the hot inner disk structure. We report that NaI and CO overtone emission lines are indeed good tracers of the rotating inner warm disk tracing from ~0.04 to ~7AU of this source. We also report the disk properties using other emission lines.

• Journal of Astronomy and Space Sciences
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• 제31권2호
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• pp.141-144
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• 2014

Recently, cave candidates have been discovered on other planets besides the Earth, such as the Moon and Mars. When we go to other planets, caves could be possible human habitats providing natural protection from cosmic threats. In this study, seven cave candidates have been found on Pavonis Mons and Ascraeus Mons in Tharsis Montes on Mars. The cave candidates were selected using the images of the Context Camera (CTX) on the Mars Reconnaissance Orbiter (MRO). The Context Camera could provide images with the high resolution of 6 meter per pixel. The diameter of the candidates ranges from 50 to 100m. Cushing et al. (2007) have analyzed the temperature change at daytime and nighttime using the Thermal Emission Imaging System (THEMIS) for the sites of potential cave candidates. Similarly, we have examined the temperature change at daytime and at nighttime for seven cave candidates using the method of Cushing et al. (2007). Among those, only one candidate showed a distinct temperature change. However, we cannot verify a cave based on the temperature change only and further study is required for the improvement of this method to identify caves more clearly.

• 천문학논총
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• 제27권5호
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• pp.411-418
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• 2012

We study the correlation between distributions of astronomical records and historical events using historical meteor (shower) records. In Korean chronicles, planets and meteor (shower) records are the most abundant astronomical phenomena. And they represent a general tendency of the number distribution of whole astronomical observations. We examine the correlation for the number distribution between meteors (showers) and planets during A.D. 1200-1700 and find that both records have a similar distribution. We classify historical events into three grades according to the social impact, and investigate the correlation between distributions of meteor (shower) records with social events, such as, new king's accession to the throne, foreign invasions, and domestic turmoils. From the statistical analysis, we cannot find any correlation between the meteor (shower) records and the political events. Therefore, we conclude that Korean historical records have not been influenced by the political events. We also examine the correlation between Chinese and Japanese meteor (shower) records and political events for A.D. 1200-1700, respectively, but cannot find any correlations between them.

• 천문학회보
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• 제38권1호
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• pp.56.1-56.1
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• 2013

We have carried out follow-up observations of transiting extrasolar planets using small- to medium-sized reflectors located in Korea. Using the 0.60m telescope stationed at CbNUO (Chungbuk National University Observatory) we have achieved a photometric precision of 1.48 milli-magnitudes (root-mean-square scatter of data) of a HAT-P-09b (transit duration of 3.43 hrs) transit light curve (transit depth ~ 1.3%) with V=12.3 mag for the host star. We expect a photometric precision of 1.0 - 1.2 milli-magnitude for brighter targets (V ~ 10 - 11 mag). The transit technique and its application will be outlined. The results of test observations will be presented and the defocus technique will be discussed.

• 천문학회보
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• 제41권1호
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• pp.77.1-77.1
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• 2016

We investigate the properties and detection conditions for the planetary caustic perturbation of close-separation planets. To find the properties of the planetary caustic perturbation, we construct deviation maps by subtracting the single-lensing magnification of the lens star from the planetary lensing magnification for various lensing parameters. We find that each deviation area of the positive and negative perturbations disappears at the same normalized source radius according to a given deviation threshold regardless of mass ratio but disappears at a different normalized source radius according to the separation. We also estimate the upper limit of the normalized source radius to detect the planetary caustic perturbation. We find simple relations between the upper limit of the normalized source radius and the lensing parameters. From the relations, we obtain an analytic condition for the detection limit of the planet, and which show that we can sufficiently discover a planet with the mass of sub-Earth for typical microlensing events. Therefore, we expect to add the number of low-mass planets in the next-generation microlensing experiments and conclude that our detection condition of the planet can be used as a important criteria for maximal planet detections considering the source type and the photometric accuracy.

• 천문학회지
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• 제33권2호
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• pp.127-135
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• 2000

We investigate the effects of planetary rotation on the exospheres of the earth and Mars with simple collisionless models. We develope a numerical code that computes exospheric densities by integrating velocity functions at the exobase with a 10 point Gauss method. It is assumed in the model that atoms above the exobase altitude move collisionlessly on an orbit under the planet's gravity. Temperatures and densities at the exobase over the globe are adopted from MSIS-86 for the earth and from Bougher et al's MTGCM for Mars. For both the earth and Mars, the rotation affects the exospheric density distribution significantly in two ways: (1) the variation of the exospheric density distribution is shifted toward the rotational direction with respect to the variation at the exobase, (2) the exospheric densities in general increase over the non-rotating case. We find that the rotational effects are more significant for lower thermospheric temperatures. Both the enhancement of densities and shift of the exospheric distribution due to rotation have not been considered in previous models of Martian exosphere. Our non-spherical distribution with the rotational effects should contribute to refining the hot oxygen corona models of Mars which so far assume simple geometry. Our model will also help in analyzing exospheric data to be measured by the upcoming Nozomi mission to Mars.

• 천문학회지
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• 제55권3호
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• pp.75-86
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• 2022

The lunar surface progressively darkens and reddens as a result of sputtering from solar wind particles and bombardment of micrometeoroids. The extent of exposure to these space weathering agents is frequently calculated as the location in a diagram of reflectance at 750 nm vs. 950 nm/750 nm color (R-C). Sim & Kim (2018) examined the R-C trends of pixels within ~3,500 craters, and revealed that the length (L) and skewness (s) of R-C trends can be employed as a secondary age or maturity indicator. We broaden this research to general lunar surface areas (3,400 tiles of 0.25° × 0.25° size) in 218 mare basalt units, whose ages have been derived from the size-frequency distribution analysis by Hiesinger et al. (2011). We discover that L and s rise with age until ~3.2 Gyr and reduce rather rapidly afterward, while the optical maturity, OMAT, reduces monotonically with time. We show that in some situations, when not only OMAT but also L and s are incorporated in the estimation utilizing 750 & 950 nm photometry, the age estimation becomes considerably more reliable. We also observed that OMAT and the lunar cratering chronology function (cumulative number of craters larger than a certain diameter as a function of time) have a relatively linear relationship.

• Journal of Astronomy and Space Sciences
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• 제24권3호
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• pp.209-218
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• 2007

이 연구에서는 김해천문대 망원경을 이용하여 측광성능을 분석하고, 시민천문대의 망원경으로 경쟁력 있는 관측의 하나로서 소행성 탐사를 제안하기 위한 관측을 수행하였다. 관측은 김해천문대의 60cm반사망원경을 이용하여 2007년 1월 13일에 이루어졌다. 관측에는 $Sch\ddot{u}ler$ BVI 필터와 1K CCD 카메라(AP8p)를 이용하였다. 측광성능을 확인하기 위해 등급이 잘 알려진 산개성단 M67의 표준성 영역을 관측하였고, 관측한 자료들로부터 표준계 변환계수, 대기소광계수 등을 얻었으며, 측광의 정밀도를 구하였다. PSF 측광을 통하여 M67의 색-등급도를 구하였고, 유용한 한계등급과 성단의 물리적 특성 등에 대해 고찰하였는데, 이 방법은 시민천문대급의 망원경의 측광성능을 측정하는 방법으로 유용하게 사용할 수 있다. 한편, 소행성 등과 같은 신천체의 발견 가능성을 조사하기 위하여 황도의 충 부근의 임의의 영역을 관측하였고, 그 결과를 논의하였다. 연구 결과, 김해천문대에서는 18.3등급보다 밝은 태양계 미세 천체의 탐사와 16등급보다 밝은 별들의 측광 관측 등이 가능함을 확인 할 수 있었다. 즉, 김해천문대의 망원경으로도 과학적이며 신뢰성 있는 관측을 수행 할 수 있음을 알 수 있었다. 이러한 결과는 시민천문대에서의 천문 연구 활동 가능성을 시사한다.

• 산업진흥연구
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• 제7권3호
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• pp.103-113
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• 2022

본 연구에서는 고전점성학(Classic Astrology)의 네이티비티(Nativity) 출생차트에서 '네이티브의 질병을 다스리는 구조를 다르게 타고났다면 네이티브의 삶에서 질병도 서로 다르게 나타날 수 있을 것이다.'는 전제하에 연구를 했다. 출생차트에서 개인이 타고난 건강을 사인(Sign, 별자리)과 플래닛(Planets, 행성)의 강약, 애스펙트(행성과의 관계)를 통하여 분석 했다. 선천적 질병을 다스리는 경우, 네이티비티 출생차트에서 네이티브가 타고난 ASC 별자리와 픽스트 스타 그리고 플래닛과의 애스펙트 관계를 살펴 연구했다. 후천적 질병을 다스리는 경우, 네이티비티 출생차트에서 질병을 다스리는 6^th하우스의 별자리과 룰러, 플래닛의 강약을 살펴 판단했다. 운의 흐름을 통해서 들어 오는 질병의 경우, 네이티브는 인생을 살면서 다양한 사고와 질병에 노출될 수 있다. 그래서 피르다리아(Firdaria)를 통해서 들어오는 플래닛의 기운과 강약, 플래닛과의 애스펙트 관계, 픽스트 스타 등을 통하여 질병의 관계를 살펴보았다. 연구 결과 네이티비티 출생차트에서 선천적으로 타고난 건강은 네이티브의 ASC 사인(별자리)과 플래닛(행성)의 강약에 따라 네이티브(Native)의 건강상태가 다르게 주어진다. 그리고 후천적 질병은 건강을 다스리는 6^th의 상태에 따라 네이티브의 건강이 결정되며 운에서 들어오는 질병은 피르다리아에서 들어오는 플래닛과 애스펙트의 관계에 따라 질병과 사고가 발생한다는 사실이 증명되었다.

• 천문학회지
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• 제7권1호
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• pp.19-23
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• 1974

The interpolation formula Chao-ch'a-shn devised for the Chinese calendar, Shou-shih-li, has been shown as the one of the 3rd order polynomial. Its 3 coefficients have been determined from the table of the Sun in Shou-shih-li. Its applications to the moon and planets are also briefly mentioned.