간행물
천문학회지 KCI 등재 SCOPUS Journal of The Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 반년간
- ISSN 1225-4614 (Print)2288-890X (Online)
- 수록기간 1968 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
제13권 제1호 (1980년 12월) 6건
1.
1980.12
구독 인증기관 무료, 개인회원 유료
Simultaneous observations of high resolution spectra of CaII H, K, λ 8542 a n d λ 8498 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 I ( K 3 ) / I ( H 3 ) ; a n d I ( λ 8498 ) / I ( λ 8542 ) arc found to be 1.3 and 1.14, respectively.
4,000원
2.
1980.12
구독 인증기관 무료, 개인회원 유료
The abundances of simple molecules are examined in terms of the time-dependent cloud evolution. The formation and destruction mechanisms of H 2 C O are reviewed. The average value of the fractional abundance of H 2 C O is derived to be in the range of 10 − 10 t o 5 × 10 − 9 . This is comparable to the observed values. The expected variations of the molecules formed from or destroyed by CO, CI, and C + whose abundances depend on the evolutionary state of the cloud are discussed.
4,000원
3.
1980.12
구독 인증기관 무료, 개인회원 유료
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 ( V = 13.5 ∼ 17.8 ) with a wide gap ( V = 16 ∼ 16.7 ) and the well defined giant branch with gaps at V=13.85 and 16.2. The turnoff point is defined at V = 17.25 ± 0.15 and (B-V) = 0.46 ± 0.02 . If we take V H B = 13.85 for NGC 6752, then Δ V = 2.80 , ( B − V ) 0 , g = 0.76 a n d Δ V T O = 3.40 and the chemical abundance is estimated to be [Fe/H]=-1.67 or Z = 4.3 × 10 − 4 a n d Y = 0.26 . 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.
4,300원
4.
1980.12
구독 인증기관 무료, 개인회원 유료
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 r c , the tidal cut off r t , and the concentration factor C).
4,000원
5.
1980.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
6.
1980.12
구독 인증기관 무료, 개인회원 유료
Defining a metal parameter ( S p ) c , 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]/ d r G = -0.06 k p c − 1 for the halo in galactocentric distance, r G <20 kpc. Our findings also imply a slow collapse of protogalaxy.
5,200원
