• 천문학회보
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• 제39권2호
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• pp.64.2-64.2
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• 2014

Interacting galaxy pairs are important for study of galaxy evolution. We selected 8,542 interacting galaxy pairs out of 593,514 KIAS-VAGC galaxy sample with 0.02 < z < 0.047 and r_mag <17.6. We then classified by their interacting features into 6 types by visual inspection. We focused on two types whose spiral tidal features extend to the center of early type galaxy (ETG) or to the edge of ETG. We compared galactic parameters of these two types with those of entire 8,542 pairs as well as between the two types. Preliminary result shows both types are very close pairs (projected distance ~ 20 kpc). Spiral galaxies in the center type are more massive but less bright than those in edge type. ETGs in the edge type are brighter but not more massive than those in the center type. The center type has a mass ratio 3.4 times greater than the edge type, but the edge type has a higher angular momentum than the center type.

• 천문학회지
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• 제29권spc1호
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• pp.123-124
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• 1996

Snapshots of eight SA and standard fields from low to high galactic latitudes were made using the KPNO 0.9m 2K $\times$ 2K CCD with a limiting magnitude from 19 to 22.5. The purpose of this study is to determine the vertical distribution of stars with respect to Galactic latitude and z-distance in comparison with the model simulation between intermediate population to the 'thick disk' component of scale height of a few kpc. Comparison of the preliminary results between observed and model simulation for 3 of the S fields shows good agreement both in V-mag and B- V color distributions. A bimodal distribution in B- V at high galactic latitude seems to be represented by a halo and 'thick disk' dwarf in the blue and by a normal disk dwarf population in the red.

• 천문학회지
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• 제29권spc1호
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• pp.85-86
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• 1996

The imaging spectroscopic observations of the Magellanic irregular galaxy NGC 4449 were made to show the detailed kinematic structure of the galaxy. Many filamentary structures and Several bubble-like structures are recognized in a 3D data cube of H$\alpha$ emission line. Velocity field shows the kpc-scale mosaic structure and counter- rotation of ionized gas.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.429-432
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• 2007

Gasification has been regarded as a very important technology to decrease environmental pollution and to obtain higher efficiency, The coal gasification process converts carbon containing coal into a syngas, composed primarily of CO and $H_2$. And the coal syngas can be used as a source for power generation or chemical material production. This paper illustrates the operation characteristics and results of pilot-scale coal syngas production facilities. The entrained-bed pilot scale coal gasifier was operated normally in the temperature range of $1,300{\sim}1,400^{\cdot}C$, $2{\sim}3kg/cm^2$ pressure. And Indonesian KPC coal produced syngas that has a composition of $46{\sim}54$% CO, $20{\sim}26$% $H_2$, and $5{\sim}8$% $CO_2$.

• 천문학회보
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• 제35권2호
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• pp.79.1-79.1
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• 2010

세종 산개성단 탐사관측 연구의 일환으로 중년 산개성단 NGC 2353에 대한 UBVI CCD 측광을 수행하였다. 측광학적인 방법으로 성단 내의 구성원을 선정하였으며, 이로부터 이 성단의 성간소광과 거리를 각각 E(B-V)=$0.10\pm0.02mag$와 $d=1.17\pm0.04\;kpc$으로 얻었다. 성단 구성원의 공간적인 분포를 통해서 성단의 형태가 북서 방향에서 남동 방향을 잇는 축을 중심으로 타원의 형태를 띠고 있는 것을 발견하였다. Padova 그룹이 제시한 이론적인 등연령 곡선을 관측한 색등급도에 맞춤으로써 이 성단의 나이를 1억 3천만년으로 추정하였으며, 이는 기존 연구보다 나이가 많은 것으로 나타났다. 구성원의 거리지수 분포에서 이 성단의 거리지수보다 밝은 곳에 나타나는 쌍성의 분포를 Gaussian 분포와 맞추어 $46\pm4%$ 정도의 최소 쌍성비율을 추정하였다. 마지막으로 광도함수와 질량함수를 유도하였고, 질량함수의 기울기는 $\Gamma=-1.4\pm0.2$를 얻었다.

• 천문학회보
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• 제43권1호
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• pp.61.4-62
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• 2018

We use smoothed particle hydrodynamics (SPH) models to study the evolution of galactic spin and the distribution of gas and young stars in the inner region of the galaxies through galaxy encounters. Specifically, we perform numerical simulations of interactions of a late- or an early-type galaxy with either a late- or an early-type galaxy with and without a gas halo at the closest approach distances of 25 and 50 kpc. We find that an early-type galaxy encountering a late-type galaxy have a higher galactic spin and more gas and young stars in the central region of the galaxy after the collision. We are analyzing the role of a gas halo on the changes of galactic spin and central mass distribution during various galaxy-galaxy encounters.

• 천문학회보
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• 제43권1호
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• pp.36.2-36.2
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• 2018

Radiative transfer models were developed to understand the optical polarizations in edge-on galaxies, which are observed to occur even outside the geometrically thin dust disk, with a scale height of ~0.2 kpc. In order to reproduce the vertically extended polarization structure, we find it is essential to include a geometrically thick dust layer in the radiative transfer model, in addition to the commonly-known thin dust layer. The models include polarizations due to both dust scattering and dichroic extinction which is responsible for the observed interstellar polarization in the Milky Way. It is found that the magnetic fields in edge-on galaxies are in general vertical (or poloidal) except the central part, where the magnetic fields are mainly toroidal. We also find that the polarization level is enhanced if the clumpiness of the interstellar medium, and the dichroic extinction by vertical magnetic fields in the outer regions of the dust lane are included in the radiative transfer model. The predicted degree of polarization outside the dust lane was found to be consistent with that (ranging from 1% to 4%) observed in NGC 891.

• 천문학회지
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• 제34권4호
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• pp.341-343
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• 2001

Here were continue the MHD study started by Santillan et al (1999) for the interaction of high-velocity clouds (HVCs) with the magnetized thick gaseous disk of our Galaxy. We use the MHD code ZEUS-3D and perform 3D-numerical simulations of this interaction, and study the formation of head-tail structures in HVCs. Our results show that clouds located above 2 kpc from mindplane present velocity and column density gradients with a cometary structure that is similar to those observed in 21 cm emission

• 천문학회보
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• 제36권2호
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• pp.105.2-105.2
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• 2011

거대 분자운의 중심에서 생성되는 무거운 별들의 탄생에 대하여는 아직도 많은 연구가 필요하다. 그것은 대부분의 이들 천체가 우리로부터 1-2 kpc 거리 이상의 먼 곳에 존재하며 별탄생 지역이 너무나 복잡하기 때문이다. 최근의 전파간섭계 등 고 분해능 관측은 이들 지역에 매우 다양한 천체물리 현상들이 함께 혼재하며, 초기 진화 과정의 알려지지 않았던 새로운 흥미로운 많은 사실들을 밝혀주고 있다. 특히 성간먼지의 얼음 맨틀과 연관되어 이들 지역에 집중적으로 존재하는 여러 복합 성간분자들은 무거운 별 탄생지역을 이해하는 매우 강력한 수단을 제공하여 준다. 물리적 환경의 차이에 따라 이들 분자들은 서로 다른 뚜렷한 천체화학적 특성을 보이며, 이것은 때로 무거운 별 탄생 현상을 이해하는 유일한 연구 수단이기도 하다. 이번 발표에서는 백조자리 X에 위치한 대표적인 별 탄생지역인 W75N와 DR21(OH) 지역에서 서브밀리미터 전파간섭계 어레이(SMA)로 관측된 복합 성간분자들의 흥미롭고 다양한 현상들을 소개한다.

• 천문학회보
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• 제39권1호
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• pp.46.1-46.1
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• 2014

In understanding "cooling flow" problem and the galaxy-SMBH co-evolution, AGN feedback is considered as one of the most important phenomena. Among various AGN feedback phenomena, X-ray cavities are particularly useful for studying AGN feedback over 10 kpc scales, as the origin of X-ray cavities is believed to be related to radio jet from AGN. For a comprehensive study of X-ray cavities, we collect all available diffuse X-ray data of galaxies in various galaxy environments, ranging from field galaxies to galaxy clusters, using the Chandra X-ray data archive. As a result we build up a sample of 87 targets showing enough X-ray photons to perform the analysis. Using modeling and unsharp masking techniques, we detected X-ray cavities and measured their physical properties (i.e., cavity size) for the 49 targets. Here, we present X-ray cavity properties and discuss environmental effects.