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형식 ( Siek Hyung ),이성재 ( Seong Jae Lee ),한경아 ( Kyoung A Han ) 충북대학교 과학교육연구소 2015 과학교육연구논총 Vol.30 No.2
1998년 9월 12일 (위상 □ = 0.90)와 2002년 8월 12일 (□ = 0.47)에 Aller 와 Hyung이 관측한 Lick 천문대의 HES 고분산 분광 자료, 그리고 2009년 10월 21일 (□ = 0.54) 보현산 천문대에서 형식과 이성재가 관측한 BOES 고분산 분광자료를 이용해 공생별 CI Cyg를 연구하였다. 방출선 윤곽과 선세기는 관측시기의 별 위상에 따라 변화를 보였다. 우리는 O I, O III, [O I], [O III], N III, [S III], Si II 선들의 윤곽을 제시하고, 이를 통해 공생별CI Cyg를 구성하는 뜨거운 백색왜성과 M4 분광형을 가진 차가운 적색거성 주변 가스의 물리적 조건에 대해 논의 하였다. We investigated the high dispersion HES data of the Symbiotic star CI Cyg observed at Lick Observatory on September 12th, 1998 (phase □ = 0.90) and on August 12th, 2002 (□ = 0.47) by Aller and Hyung. along with the BOES data observed at Bohyunsan Observatory on October 21st, 2009 (□ = 0.54) by Hyung and Lee. The emission line profiles and their line intensities show change depending on the phase of different observing periods. We present the line profiles of O I, O III, [O I], [O III], N III, [S III], and Si II and discuss the physical condition of the nebulous gas surrounding two components of the symbiotic star CI Cyg, i.e., a small hot white dwarf and a cold M4 type red giant star.
A BIPOLAR PLANETARY NEBULA NGC 6537: PHOTOIONIZATION OR SHOCK HEATING?
HYUNG SIEK The Korean Astronomical Society 1999 Journal of The Korean Astronomical Society Vol.32 No.1
NGC 6537 is an extremely high excitation bipolar planetary nebula. It exhibits a huge range of excitation from lines of [N I] to [Si VI]or [Fe VII], i.e. from neutral atoms to atoms requiring an ionization potential of $\~$167eV. Its kinematical structures are of special interest. We are here primarily concerned with its high resolution spectrum as revealed by the Hamilton Echelle Spectrograph at Lick Observatory (resolution $\~0.2{\AA}$) and supplemented by UV and near-UV data. Photoionization model reproduces the observed global spectrum of NGC 6537, the absolute H$\beta$ flux, and the observed visual or blue magnitude fairly well. The nebulosity of NGC 6537 is likely to be the result of photo-ionization by a very hot star of $T_{eff} \~ 180,000 K$, although the global nebular morphology and kinematics suggest an effect by strong stellar winds and resulting shock heating. NGC 6537 can be classified as a Peimbert Type I planetary nebula. It is extremely young and it may have originated from a star of about 5 $M_{\bigodot}$.
IUE SPECTRA OF THE SEYFERT 1 GALAXIES Mrk 335 and NGC 4051
HYUNG SIEK,KIM HYOUK,LEE Woo BAlK,LEE SEONG-JAE,RYU DONGSU,LEE HEE-WON The Korean Astronomical Society 2000 Journal of The Korean Astronomical Society Vol.33 No.2
The international ultraviolet explorer (IUE) spectra of a low dispersion $\~6{\AA}$, have been investigated for two Seyfert 1 galaxies, Mrk 335 and NGC 4051, well known for the line variability. The electron densities of broad line region (BLR) of these variable Seyfert 1 galaxies have been derived, which showed a non-linear abrupt variation from $10^8$ to $10^{10} cm-3$ within a month. We also found the excitation (or temperature) changes in the Mrk 335 BLR from the IUE broad line profiles analysis, but no such evidence in the NGC 4051. The large amount of mass inflow activity through the bar or spiral structure of host galaxies, may trigger the density change in BLR and emission line variability for both objects. Mass of the giant black holes appear to be order of $10^7\;M_{\bigodot}$ for both variable Seyfert l's.
ABUNDANCES OF PLANETARY NEBULAE IN M 31 AND M 32
HYUNG SIEK,ALLER LAWRENCE H.,HAN SOO-RYEON,KIM YOUNG-KWANG,HAN WONYONG,CHOI YOUNGJUN The Korean Astronomical Society 2000 Journal of The Korean Astronomical Society Vol.33 No.2
Planetary nebulae provide a direct way to probe elemental abundances, their distributions and their gradients in populations in nearby galaxies. We investigate bulge planetary nebulae in M 31 and M 32 using the strong emission lines, H$\alpha$, He I, [O III], [N II], [S II] and [Ne III]. From the [O III] 4363/5007 line ratio and the [O II] 3727/3729, we determine the electron temperatures and number densities. With a standard modeling procedure (Hyung, 1994), we fit the line intensities and diagnostic temperatures, and as a result, we derive the chemical abundances of individual planetary nebulae in M 31 and M 32. The derived chemical abundances are compared with those of the well-known Galactic planetary nebulae or the Sun. The chemical abundances of M 32 appear to be less enhanced compared to the Galaxy or M 31.