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1968년 ~ 2024년까지 1,211 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 : 1,211건 (DB Construction : 1,211 Articles)
총 게시글 1,211건
페이지 116/122
1151
- Chun, M.S.
- 天文學會誌 = The journal of the Korean Astronomical Society
- 14, n.1
- pp.13-17
- 1981
- 원문 바로보기
The observed radial UBV colour variations (both B-V and U-B) of some globular clusters are examined for correlations with radial variations in the integrated spectra. The results show that the presence of a radial colour gradient is correlated with the presence of a gradient of the CN (and possibly the G-band) line strength, in the sense that the CN (and possibly the G-band) is stronger in the centre (where the cluster is redder) and becomes weaker in the outer region of the cluster (where the cluster is bluer). This may suggest that a primordial abundance, possibly nitrogen and carbon gradient was set up in the early stage of cluster formation.
1152
- Lee, H.M.
- 天文學會誌 = The journal of the Korean Astronomical Society
- 14, n.2
- pp.79-87
- 1981
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Theoretical profiles of selected rotational lines of <TEX>$C_2$</TEX> CH, CN, TiO and MgH are computed by using the current models of sunspot unbrae and penumbrae. It is found that the lines of the diatomic carbides are enhanced in penumbrae relative to umbrae, while MgH lines are more strongly enhanced in umbrae than in penumbrae and the quiet photosphere. The results are discussed with respect to selecting lines suitable for studying the structure of sunspots.
1153
- Hong, Seung-Soo
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.35-44
- 1980
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Various assumptions used in interpreting the observations of hydrogen recombination lines are critically assessed to confirm the gradient of electron temperature with distance from the galactic center. The total temperature increase from 5 to 13 kpc is about 2,500 K. Among many suggestions, we have singled out the decrease of trace dement abundances with the galactoccntric distance as the most viable cause for the temperature gradient. This will impose an important constraint on evolutionary models of the Galaxy.
1154
- Chun, M.S.
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.27-33
- 1980
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Surface density distributions for globular clusters were obtained from photoelectric surface photometry (using centered aperture photometry). These surface brightness profiles were then compared with the theoretical surface density distribution of King's model. From the comparison of the theoretical and observed surface density distributions, we determine he structural parameters of the clusters (the core radius <TEX>$r_c$</TEX>, the tidal cut off <TEX>$r_t$</TEX>, and the concentration factor C).
1155
- Lee, See-Woo
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.45-62
- 1980
- 원문 바로보기
Defining a metal parameter <TEX>$(Sp)_c$</TEX>, which is related to the morphological parameters of C-M diagrams, we have estimated metal abundances for 97 globular clusters in our Galaxy. A correlation between absolute magnitude of the horizontal branch and metal abundance is derived, which is used for the determining distances to globular clusters whose visual magnitudes of the horizontal branch are known. The space distribution of globular clusters and the chemical evolution of the halo are examined. Our analysis suggests an initial mean gradient of metallicity to be d[Fe/H]/<TEX>$dr_G$</TEX> = -0.06 <TEX>$kpc^{-1}$</TEX> for the halo in galactocentric distance, <TEX>$r_G$</TEX><20 kpc. Our findings also imply a slow collapse of protogalaxy.
1156
- Minn, Y.K.
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.9-14
- 1980
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The abundances of simple molecules are examined in terms of the time-dependent cloud evolution. The formation and destruction mechanisms of <TEX>$H_2CO$</TEX> are reviewed. The average value of the fractional abundance of <TEX>$H_2CO$</TEX> is derived to be in the range of <TEX>$10^{-10}\;to\;5{\times}10^{-9}$</TEX>. This is comparable to the observed values. The expected variations of the molecules formed from or destroyed by CO, CI, and <TEX>$C^+$</TEX> whose abundances depend on the evolutionary state of the cloud are discussed.
1157
- Yun, Hong-Sik
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.1-8
- 1980
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Simultaneous observations of high resolution spectra of CaII H, K, <TEX>${\lambda}8542\;and\;{\lambda}8498$</TEX> have been made over a sunspot umbra (SPO 5007) by means of Sacramento Peak Observatory's HIRKHAD program with the Echelle spectrograph at the Vacuum Tower Telescope. The observed spectra scanned by SPO's fast microphotometer have been reduced for later theoretical interpretations. The reduced profiles, sampled over a region which is thought to be coolest over the spot, are presented in units of absolute intensity. The core intensity ratios of <TEX>$I(K_3)/I(H_3);and\;I({\lambda}8498)/I({\lambda}8542)$</TEX> arc found to be 1.3 and 1.14, respectively.
1158
- Lee, See-Woo
- 天文學會誌 = The journal of the Korean Astronomical Society
- 13, n.1
- pp.15-26
- 1980
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The BV-photographic photometry was made for 1714 stars (V<19.5) in NGC 6752. The C-M diagram of this cluster shows an unusually extended blue horizontal branch <TEX>$(V=13.5{\sim}17.8)$</TEX> with a wide gap <TEX>$(V=16{\sim}16.7)$</TEX> and the well defined giant branch with gaps at V=13.85 and 16.2. The turnoff point is defined at <TEX>$V=17.25{\pm}0.15$</TEX> and (B-V) = <TEX>$0.46{\pm}0.02$</TEX>. If we take <TEX>$V_{HB}=13.85$</TEX> for NGC 6752, then <TEX>${\Delta}V=2.80,\;(B-V)_{0,g}=0.76\;and\;{\Delta}V_{TO}=3.40$</TEX> and the chemical abundance is estimated to be [Fe/H]=-1.67 or <TEX>$Z=4.3{\times}10^{-4}\;and\;Y=0.26$</TEX>. Some other physical parameters of this cluster are derived and compared with those for the well observed clusters M 3, M 13, M 15 and M 92.
1159
- 나일성
- 天文學會誌 = The journal of the Korean Astronomical Society
- 12, n.1
- pp.35-40
- 1979
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Astronomical records in the days of King Jeongjo of Yi dynasty, 1777-1800, are examined for solar and lunar eclipses, meteors and comets. The books used for this investigation are Sung Jeong Won Il Gi, which are the original daily records written in the court. The records found in these Sung Jeong Won Il Gi are tabulated according to the four astronomical phenomena above, and they were cross checked with the records in the book, Jung Bo Mun Heon Bi Go. Although Jung Bo Mun Heon Bi Go has most frequently been used as the original records to those who work for the ancient Korean records, the inaccuracy and the deficiency are found.
1160
- Chun, M.S.
- 天文學會誌 = The journal of the Korean Astronomical Society
- 12, n.1
- pp.11-15
- 1979
- 원문 바로보기
Four stars in the central region of 47 Tuc were observed spectroscopically using IPCS. The observed result showed that two asymptotic giant branch stars have the excess of nitrogen compared with the red giant branch stars, which indicates that the radial colour gradient in a globular clursters, at least for 47 Tuc, comes from the abundance gradient among the giant stars.