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1968년 ~ 2023년까지 1,187 건의 한국천문학회지를 격월간 확인하실 수 있습니다.
- The Korean Astronomical Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-4614 (ISSN : 1225-4614)
1225-4614
- DB구축현황 : 1,187건 (DB Construction : 1,187 Articles)
총 게시글 1,187건
페이지 94/119
931
- PARK SEOK JAE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.97-98
- 1996
- 원문 바로보기
Variability of active galactic nuclei is now a well-known phenomenon. This remains to be fully explained by a theoretical model of the central engine. Time scales of AGN variability seem to range continuously from hours up to months. The short time scale variability must be related to the phenomena on the event horizon of the black hole, while the long one to those in the accretion disk or surrounding matter. Based on the axisymmetric, nonstationary model of the central engine, we discuss theoretical considerations on the variability of active galactic nucleus.
932
- YANG SUNG-CHUL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.141-142
- 1996
- 원문 바로보기
933
- UMEDA HIDEYUKI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.23-24
- 1996
- 원문 바로보기
We reexamined CDM texture large-scale structure (LSS) formation model. We confirmed that texture model is consistent with 4-year COBE data both in an open and a critical matter density (<TEX>${\Omega}_0$</TEX> = 1) universes, and then obtained normalization for density perturbation power spectrum. We next compare the power spectrum with LSS observation data. Contrary to the previous literature, we found that texture model matches with these data in an open universe no better than in an <TEX>${\Omega}_0$</TEX> = 1 universe. We also found that the model is more likely to fit these data in a cosmological constant dominated (<TEX>$\Lambda-$</TEX>) universe.
934
- CHEN JIAN-SHENG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.407-407
- 1996
- 원문 바로보기
935
- ANN HONG-BAE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.2
- pp.255-268
- 1996
- 원문 바로보기
We present VR CCD photometry and long-slit spectroscopy of a late type spiral galaxy NGC 7678. The grey scale images and isophotal maps illustrate the presence of a weak bar from which spiral arms emerge. There are many HII regions along the spiral arms, but bright giant HII regions are more concentrated in the massive southern arm. The bright compact nucleus of NGC 7678 is bluer than bulge and bar. The spectral features of the nucleus and HII regoins are very similar but the nuclear spectra shows higher <TEX>$[NII]{\lambda}6583/H_\alpha$</TEX> than those of the HII regions. The nucleus of NGC 7678 seems to be intermediate type between HII region nulcei and LINERs by the ratio of <TEX>$[NII]{\lambda}6583/H_\alpha$</TEX>, but it is more likely to be HII region-like nucleus if we consider the <TEX>$[NII]{\lambda}6716,6731/H_\alpha$</TEX> together. The star formation rate is estimated to be about <TEX>$0.2 M_\bigodot\;yr^{-1}$</TEX> based on the <TEX>$H_\alpha$</TEX> flux.
936
- KIM T.-S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.39-40
- 1996
- 원문 바로보기
Using the Keck 10 m telescope data with the HIRES spectrograph, we analyzed the evolution of Lyman<TEX>$\alpha$</TEX> forest clouds at z > 2 down to the HI column density <TEX>$10^{12.8}cm^{-2}$</TEX>. The number density per unit column density does not change with redshifts at lower HI cloumn density (<TEX>$N_{HI} < 10^{14}cm^{-2}$</TEX>), while the forest clouds at higher column density disappear rapidly. The cutoff b value, the thermal temperature indicator, increases as redshift decreases. The correlation strength seems to be stronger as redshift decreases.
937
- PARK CHANGBOM
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.433-437
- 1996
- 원문 바로보기
We have analyzed the content of the Korean stone star chart. Ch'on-Sang-Yul-Cha-Bun-Ya-Ji-Do(here-after Ch'on-Sang-Do). In the star map we have found 1468 stars, 4 more than the Chinese star catalog Bo-Chun-Ga. The four extra stars form a constellation, Jong Dae Boo. The map projection law used in the star chart is found to be the polar equtorial and equidistance projection. The linear distance of an object on Ch'on-Sang-Do from the center is linearly proportional to the north polar angular distance. We have found from a statistical analysis that most stars with declination lower than 50 are at positions representing the epoch of around the first century. On the other hand, stars near the north pole with declination higher than 50 are at the epoch of about 1300, which is close to the time the chart was engraved. This implies that the original Ko-Gu-Rye Dynasty's star chart has been revised by astronomers of Cho-Sun Dynasty. We have also shown that stars on Ch'on-Sang-Do are engraved in such a way that their area is linearly proportional to the visual magnitude.
938
- PENG QIUHE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.69-70
- 1996
- 원문 바로보기
939
- KIM SANG-JOON
- Journal of the Korean astronomical society = 천문학회지
- 29, n.2
- pp.223-243
- 1996
- 원문 바로보기
We have constructed a line-by-line model of the A-X system of CO in order to analyze the CO bands appearing in the UV spectra of comets. The model includes electronic, rotational, vibrational transitions, excitations by solar UV radiation, and effects of neutral and electron collisions. The major bands of the A-X system occur in the <TEX>$1200 - 1800{\AA}$</TEX> range where the temporal variation of solar irradiation is significant. The solar spectrum in this spectral range shows many emission lines, which cause a significant Swings effect. We derived fluorescence efficiencies of the bands as functions of heliocentric velocity and cometocentric distance using a high resolution spectrum of the sun. We compared our model with a spectrum of comet P/Halley obtained with the IUE, and estimated that the UV Swings effects are less than 20 fluorescence efficiencies for the most bands of the A-X system. We discuss the temporal variation of solar UV irradiation and its effects on the fluorescence efficiencies. The study of the A-X system also requites knowledge of vibrational and rotational fluorescent processes in the infrared and radio regions because the majority of CO molecules in the coma is in the ground rotational states. The solar infrared spectrum near 5 microns, where the fundamental band of CO occurs, contains strong absorption lines of the fundamental band and hot bands of CO and its isotopes. We derived fluorescence efficiencies of the infrared band as functions of heliocentric velocity and cometrocentric distance. The solar absorption lines near 5 microns cause a 20 reduction of the g-factor of the fundamental band at heliocentric velocities close to 0 km/sec. We discuss the effects of neutral and electron collisions on the fluorescence efficiencies of the infrared and UV bands.
940
- KOZHANOV T. S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.27-29
- 1996
- 원문 바로보기
We describe the formation of large-scale inhomogeneous structure of expa-nding Universe on the basic of two components system-usual nonrelativistic particles and dark matter, with taking into account their interaction.