• 천문학회지
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• 제40권4호
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• pp.157-160
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• 2007

I present a model to explain the mass segregation and shallow mass functions observed in the central parts of starburst stellar clusters. The model assumes that the initial pre-stellar cores mass function resulting from the turbulent fragmentation of the proto-cluster cloud is significantly altered by the cores coalescence before they collapse to form stars. With appropriate, yet realistic parameters, this model based on the competition between cores coalescence and collapse reproduces the mass spectra of the well studied Arches cluster. Namely, the slopes at the intermediate and high mass ends, as well as the peculiar bump observed at $6M_{\bigodot}$. This coalescence-collapse process occurs on a short timescale of the order of the free fall time of the proto-cluster cloud (i.e., a few $10^4$ years), suggesting that mass segregation in Arches and similar clusters is primordial. The best fitting model implies the total mass of the Arches cluster is $1.45{\times}10^5M_{\bigodot}$, which is slightly higher than the often quoted, but completeness affected, observational value of a few $10^4M_{\bigodot}$. The model implies a star formation efficiency of ${\sim}30$ percent which implies that the Arches cluster is likely to a gravitationally bound system.

• 천문학회지
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• 제44권4호
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• pp.135-142
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• 2011

A $200'{\times}200'$ region around 30 Doradus in the Large Magellanic Cloud (LMC) is observed and analyzed in the near-infrared. We obtain polarimetry data in the J, H, and Ks bands using the SIRIUS polarimeter SIRPOL at the Infrared Survey Facility 1.4 m telescope. We measure the Stokes parameters of 2562 point-like sources to derive the degree of polarization and the polarization position angles. We discuss the statistics of the groups classified by color-magnitude diagram and proper motions of the sources, in order to separate the Galactic foreground sources from those present in the LMC. We notice that groups classified by the proper motion data show a tendency towards different polarimetric properties.

• 천문학논총
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• 제30권2호
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• pp.109-112
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• 2015

We present [$Fe\;{\small{II}}$] ${\lambda}1.257{\mu}m$ spectra toward the interacting binary UY Aur with 0".14 angular resolution, obtained with the Near infrared Integral Field Spectrograph (NIFS) combined with the adaptive optics system Altair of the GEMINI observatory. In the [$Fe\;{\small{II}}$] emission, UY Aur A (primary) is brighter than UY Aur B (secondary). The blueshifted and redshifted emission between the primary and secondary show a complicated structure. The radial velocities of the [$Fe\;{\small{II}}$] emission features are similar for UY Aur A and B: ${\sim}-100km\;s^{-1}$ and ${\sim}+130km\;s^{-1}$ for the blueshifted and redshifted components, respectively. Considering the morphologies of the [$Fe\;{\small{II}}$] emissions and bipolar outflow context, we concluded that UY Aur A drives fast and widely opening outflows with an opening angle of ${\sim}90^{\circ}$ while UY Aur B has micro collimated jets.

• 천문학회보
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• 제44권1호
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• pp.77.1-77.1
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• 2019

It has been proposed by Gunn & Gott (1972) that galaxies may lose their interstellar gas by ram pressure due to the dense intra-cluster medium while falling to the cluster potential. The observational evidence for this process, which is known as ram pressure stripping, is increasing, and it is believed to be one of the key environmental effects that can dramatically change the star formation activity of galaxies and hence their evolution. Intriguingly however, some cases with clear signs of ram pressure stripping are found in the environment which betrays our expectations (e.g. large clustercentric distances), and our understandings to the detailed working principle behind ram pressure stripping seem to be still lacking. As one of the ways to gain more theoretical insights into the conditions for ram pressure stripping process, we have been comparing the gas truncation radius which is predicted based on the simple Gunn & Gott's prescription with what is actually observed in a sample of carefully selected Virgo galaxies. In this work, we present the results of our comparisons between the theoretically predicted truncation radius and the observationally measured truncation radius for individual galaxies in the sample and discuss which additional conditions are needed in order to fully understand the observations.

• 천문학논총
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• 제27권4호
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• pp.253-256
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• 2012

We present the IRC images of M51, a pair of interacting galaxies. Given the high angular resolution (7.4") and the wide field of view (~ 10') covering almost the entire M51 system, we investigate dust properties and their connection to the spiral arm structure. We have applied image-filtering processes including the wavelet analysis to the N3 image, which traces the total stellar mass best among the IRC bands. From this filtered image, the center, arm, and interarm regions are defined. A color, or flux ratio among the MIR bands, has been measured at each pixel (3.7" in size). We find a wide variety of S7/S11 with a difference between arm and interarm regions. We also find that at some positions S11 seems to be higher than predicted by MW dust models. Estimated contributions from the stellar continuum and gas emission lines to the band are not enough to explain this discrepancy. From these results, we deduce that the PAH ionization condition and its fraction to the total dust mass in M51 are different from those in MW.

• 천문학회지
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• 제38권2호
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• pp.169-172
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• 2005

We present CO(3-2), CO(2-1), and 230 GHz (1.3 mm) continuum images of nearby galaxies taken with the Submillimeter Array (SMA). Our main topic is to study the relation between higher-J molecular gas (e.g., CO J=3-2, 2-1) and nuclear activities (e.g., active galactic nuclei [AGNs] and starbursts). The nearby Seyfert 2 galaxy M51 shows strong CO(3-2) emission from the circumnuclear molecular gas, with an intensity twice as strong as that of the CO(1-0) emission. Strong CO(3-2) emission enhancement suggests that the circum nuclear molecular gas in M51 is warm and dense, which may be related to the AGN activities. Molecular gas in the nearby moderate starburst galaxy NGC 6946 is distributed along the large-scale bar or spiral arms and along the minibar, and the multi-J CO line images show very similar distribution to each other. For this galaxy, there is no clear enhancement in higher-J lines as seen in M51, which may be because NGC 6946 does not have clear AGN activities. Based on the results of these two galaxies, the physical conditions of the circum nuclear molecular gas may be related to the AGN activities. We also observed the nearby edge-on starburst galaxy NGC 3628 and the starburst/Seyfert composite galaxy NGC 4945 with the CO(2-1) line and 230 GHz (1.3 mm) continuum emission. These information will give us some hints for understanding the relation between nuclear activities and circum nuclear molecular gas and dust.

• 천문학회보
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• 제43권1호
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• pp.45.1-45.1
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• 2018

Formation of filaments and subsequent dense cores in ISM is one of the essential questions to address in star formation. To investigate this scenario in detail, we recently started a molecular line survey namely 'Filaments, the Universal Nursery of Stars (FUNS)' toward nearby filamentary clouds in Gould Belt using TRAO 14m single dish telescope equipped with a 16 multi-beam array. In the present work, we report the first look results of kinematics of a low mass star forming region L1478 of California molecular cloud. This region is found to be consisting of long filaments with a hub-filament structure. We performed On-The-Fly mapping observations covering ~1.1 square degree area of this region using C18O(1-0) as a low density tracer and 0.13 square degree area using N2H+(1-0) as a high density tracer, respectively. CS (2-1) and SO (32-21) were also used simultaneously to map ~290 square arcminute area of this region. We identified 10 filaments applying Dendrogram technique to C18O data-cube and 13 dense cores using FellWalker and N2H+ data set. Basic physical properties of filaments such as mass, length, width, velocity field, and velocity dispersion are derived. It is found that filaments in L~1478 are velocity coherent and supercritical. Especially the filaments which are highly supercritical are found to have dense cores detected in N2H+. Non-thermal velocity dispersions derived from C18O and N2H+ suggest that most of the dense cores are subsonic or transonic while the surrounding filaments are transonic or supersonic. We concluded that filaments in L~1478 are gravitationally unstable which might collapse to form dense cores and stars. We also suggest that formation mechanism can be different in individual filament depending on its morphology and environment.

• 복식문화연구
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• 제10권6호
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• pp.748-762
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• 2002

The purpose of this study was to analyze the fashion trends of Korean men's golfwears and furnished the researchers of same major with reliable data base. Lately, Korean men were concerned about their appearance rather than social position. Moreover, they tried to express the needs of youthfulness with free lift through clothings. These trend had been showed itself not only development of golfwears, but also change of esthetic tastes of men's golfwears. First of all, the development of men's golfwears was affected by the major three factors out of many various factors. That is, popularization of golf by the international activities of Korean progolfers, appearance of young consumers after IMF and the casualization of the men's formal dress, the making an everyday dress of men's sportswears. The results of analyzing of fashion trends of the men's golfwears is as follow: 1. The characteristics with naturalness, comfort of men's golfwears was manifested casualization trends by the factors of downward tendency of golfer's age, 5-days working, men's biz casual preference, individual ism after IMF. 2. Men's character golfwears was showed by the ageless as a youthfulness expression, the Sportism as an international trend, 2002 world cup, etc. 3. All of golfwears have to be functional characteristics because the golf is an active sports spending long time in golf course. Unconstruction style was an important fashion trends of men's golfwears by using functional materials to meet the needs of consumers. 4. The men's clothing was deviated from a fixed idea called masculine after IMF. Moreover, this trend was increased by the appearance of lovely man, genderlessness and had an effect on men's golfwears. Consequently. men's golfwears was showed feminization characteristics as a feminine, sensitive style. In the future, Korean men will try to express their character and thought freely through golfwears, men's golfwears will be continued ‘beyond the golf course’ image reflecting in the future fashion trends.

• 천문학회보
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• 제46권2호
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• pp.65.2-66
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• 2021

Observational studies of supernova (SN) feedback are limited. In our galaxy, most supernova remnants (SNRs) are located in the Galactic plane, so there is contamination from foreground/background sources. SNRs located in other galaxies are too far, so we cannot study them in detail. The Large Magellanic Cloud (LMC) is a unique place to study the SN feedback due to their proximity, which makes possible to study the structure of individual SNRs in some detail together with their environment. Recently, we carried out a systematic study of 13 LMC SNRs using [P II] (1.189 ㎛) and [Fe II] (1.257 ㎛) narrowband imaging with SIRIUS/IRSF, four SNRs (SN 1987A, N158A, N157B and N206), show [P II]/[Fe II] ratio much higher than the cosmic abundance. While the high ratio of SN 1987A could be due to enhanced abundance in SN ejecta, we do not have a clear explanation for the other cases. We investigate the [P II] knots found in SNRs N206, N157B and N158A, using optical spectra obtained last November with GMOS-S mounted on Gemini-South telescope. We detected several emission lines (e.g., H I, [O I], He I, [O III], [N II] and [S II]) that are present in all three SNRs, among other lines that are only found in some of them (e.g., [Ne III], [Fe III] and [Fe II]). Various line ratios are measured from the three SNRs, which indicate that the ratios of N157B tend to differ from those of other two SNRs. We will use the abundances of He and N (from the detection of [N II] and He I emission lines), together with velocity measurements to tell whether the origin of the [P II] knots are SN ejecta or CSM/ISM. For this purpose we have built a family of radiative shock with self-consistent pre-ionization using MAPPINGS 5.1.18, with shock velocities in the range of 100 to 475 km/s. We will compare the observed and modeled line fluxes for different depletion factors.

• 한국과학교육학회지
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• 제19권1호
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• pp.41-61
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• 1999

본 논문은 정성적인 연구방법의 하나인 문헌분석법에 의하여 이루어졌다. 문헌 분석의 방법은 본 논문의 목적에 비추어 교육철학, 교육이론, 과학철학, 교육심리학, 통합교육과정과 관련된 국내 외의 주요 단행본, 연구보고서 및 논문, 전문지에 수록된 자료를 수집하고, 이를 연구내용에서 제시한 관점에 따라 분류 분석 추출 정립하였다. 이를 바탕으로 통합과학교육의 방향을 설정하였다. 즉, 먼저 과학의 본성을 과학지식으로 보는 관점, 사회적 합의과정으로 보는 관점, 개인 삶의 창조로 보는 관점의 3가지, 그리고 교육의 본성을 지식의 형식으로 보는 관점, 경험의 확대로 보는 관점, 자아실현으로 보는 관점의 3가지로 분류하고, 이를 근거로 하여 통합과학교육의 방향을 지식내용중심, 사회문제 중심, 개인흥미중심의 3가지로 모색하였다. 다음으로, 이상에서 모색된 지식내용중심, 사회문제중심, 개인흥미중심의 3가지 통합과학교육의 방향이 교육철학적, 과학철학적, 교육심리학적 측면에서 정당화되는 근거를 밝혔다. 마지막으로 이상에서 정당화된 이론적 근거를 바탕으로 하여, 통합과학교육의 방향을 지식내용중심, 사회문제중심, 개인흥미중심의 방향의 3가지로 설정하였다. 여기서 설정된 3가지 통합과학교육의 방향은 앞으로 후속 논문의 논지를 이끄는 데 기본적인 준거가 될 것이다. 이러한 연구 단계에 따라 분석된 연구의 결과를 요약하면 다음과 같다 첫째, 과학의 본성을 '과학지식' 으로, 교육의 핵심을 '지식의 형식' 으로 보는 관점을 이론적 근거로 하여 지식내용중심의 통합과학교육이 설정된다. 따라서 이는 'Hirst의 통합논리' 가 바탕이 된다고 할 수 있으며, 통합화의 초점은 지식의 의미와 그들간의 논리적 관련성을 탐구양식에 따라 보다 분명히 밝히려는데 있다. 둘째, 과학의 본성을 '사회적 합의과정'으로 교육의 핵심을 '경험의 확대'로 보는 관점을 이론적 근거로 하여 사회문제중심의 통합과학교육이 설정된다. 따라서 이는 'Dewey의 통합논리'가 바탕이 된다고 할 수 있으며, 통합화의 초점은 사회적 경험의 과정을 용이하게 해 주는 방법적 측면에 있다. 셋째, 과학의 본성을 '개인 삶의 창조'로 교육의 핵심을 '자아실현'으로 보는 관점을 이론적 근거로 하여 개인흥미중심의 통합과학교육이 정당화될 수 있다. 따라서 이는 'Patterson 의 통합논리'가 바탕이 된다고 할 수 있으며, 통합화의 초점은 개인의 자아실현을 위한 심리적 측면에 있다. 앞으로 학교현장에서 "효과적인" 통합과학교육이 이루어지기 위하여는 본 연구에서 논의된 통합과학교육의 방향을 이론적 준거로 하여, 교사 교재 학생의 역동적인 관계성을 고려한, 체계적이고 종합적인 통합과학교육과정이 개발되어야 한다. 그리고 개발된 통합과학교육과정을 교사가 실제로 학교수업에 충분히 활용할 수 있도록 하는 노력을 기울여야만 한다.