CFHT 천문대 3.6 m 망원경에 부착된 OASIS 분광기를 사용하여 얻은 자료로부터 continuum, Hα, Hβ, [O III], [N II] 등의 영상을 만들어 활동 은하핵 NGC 5728의 물리적 특성을 분석하였다. NGC 5728의 중심부에 NLR 영역으로 판단되는 약 15"×12" 범위 영역에 3개의 밝은 부분(NW knot, SE knot, nucleus)이 존재하고 있고, 이는 핵(nucleus)을 중심으로 북서방향이나 서쪽으로 물질의 흐름이 일어나고 있음을 암시한다. 우리는 직경 10"인 ring과 이의중심에 있는 NW knot의 구조가 은하중심과 일치하지 않음을 발견하였다. 우리는 이러한 구조의 생성 원인에 대해 알아보기 위하여 핵과 knot의 운동학적 특성을 비교하여 보았고, 방출선 영상에서 보이는 차이점을 비교함으로써 활동 은하 중심부의 구조를 살펴보았다.

Chemical evolution of galaxies can be understood by studying the spatial distribution of heavy elements. We selected two nearby galaxies, M31 and M33 and investigated spectrum of their HII regions: a) the elec-tron densities have been derived from the [S II] 6717/6731 ratio along with the most recent atomic constants (Hyung & Aller 1996); b) the electron temperatures were determinated from the Pagel's empirical method. Nebula Model (Hyung 1994) has been employed to predict the spectral line intensities which gives the proper chemical abundances. The model would predict the line intensities correctly only when various input parameters such as the effective central star temperatures, gravity log g, model atmosphere as well as the geometry and the nebula physical condition are appropriate. Thus, the determination of chemical abundances of O, S, N of the two nearby galaxies M31 and M33 has been done, which shows a radial dependance of O/H and N/H: decrease with the distance, or increasing electron temperature due to the elemental deficiency. Abundances of M31 appear to be enhanced than those of M33.

We have reviewed the magnetic activity in close binaries. Solar like magnetic activity indicators such as photometric spots, chromo spheric emission, coronal X-ray and radio emission, and flare activity are commonplace in many cool stars with convective envelopes. Using the UV spectra we confirmed the strength of stellar activity increases with more rapid rotation and later spectral types which corresponds to the increasing depth of the star's convective envelope. Apart from very young stellar objects such as T Tauri stars, the stars with the highest levels of activity are close binary systems composed of cool stars, i.e., the chromospherically active binaries such as RS CVn, BY Dra, W UMa and related systems. The IUE low and high dispersion spectra of V711 Tau, VW Cep and SW Lac are used for ultraviolet photometry and for a variation study of chromospheric activity. Evidence of chromospherically activity is indicated by the intensity variation of the Mg II emission line with orbital phase.

Korea Astronomy Observatory (KAO) recently developed a new model of CCD imaging system for astronomical purpose. This paper presents system structure and electrical circuit descriptions with the performance of the CCD imaging system. The developed system can handle astronomical image acquisition with additional functions of on-chip binning, sub-image acquisition using a SITe 1024×1024 1024×1024 CCD chip. Particularly the controller design of the system allows us great flexibility and versatility with the software system control and it is possible to cope with any format CCDs by any manufactures, in principle. The system performances are derived by mean variance test in our laboratory, which shows that the total system noise 10.5e-(R.M.S), Gain 1.9e-/ ADD, non-linearity 0.37% 0.37%