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
제14권 제2호 (1981년 12월) 5건
1.
1981.12
구독 인증기관 무료, 개인회원 유료
The characteristic size and mass of galaxies as pre-galactic constraints on the Galactic evolution are reviewed and the general constraints for their existence in gravitationally bound systems are examined. Implications on the self-similar gravitational clustering are also discussed.
3,000원
2.
1981.12
구독 인증기관 무료, 개인회원 유료
On the basis of observational constraints, particularly the relationship between metal abundance and cumulative stellar mass, a simple two-zone disk-halo model for the chemical evolution of our Galaxy was investigated, assuming different chemical processes in the disk and halo and the infall rates of the halo gas defined by the halo evolution. The main results of the present model calculations are: (i) The halo formation requires more than 80% of the initial galactic mass and it takes a period of 2 ∼ 3 × 10 9 yrs. (ii) The halo evolution is divided into two phases, a fast collapse phase ( t = 2 ∼ 3 × 10 8 yrs) during which period most of the halo stars ( ∼ 95 are formed and a later slow collapse phase which is characterized by the chemical enrichment due to the inflow of external matter to the halo. (iii) The disk evolution is also divided into two phases, an active disk formation phase with a time-dependent initial mass function (IMF) up to t ≈ 6 × 10 9 yrs and a later steady slow formation phase with a constant IMF. It is found that at the very early time t ≈ 5 × 10 8 yrs, the metal abundance in the disk is rapidly increased to ∼ 1 / 3 of the present value but the total stellar mass only to ∼ 10 of the present value, finally reaching about 80% of the present values toward the end of the active formation phase.
5,100원
3.
1981.12
구독 인증기관 무료, 개인회원 유료
On the basis of the recently available data, we have analysed the kinematical properties of nearby dwarfs, which are grouped by their spectral types and derived their ages from the kinematical properties. The discontinuities in the kinematical properties are found around late F stars, which appear to be caused mainly by the fact that the spectral groups earlier than late F are rather homogencous in age while the later ones are mixed by two different age group.
4,000원
4.
1981.12
구독 인증기관 무료, 개인회원 유료
Theoretical profiles of selected rotational lines of C 2 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.
4,000원
5.
1981.12
구독 인증기관 무료, 개인회원 유료
Weibull analyses given to the initial mass function (IMF) deduced by Miller and Scalo (1979) have shown that the mass dependence of IMF is an exp [ − α m ] - form in low mass range while in the high mass range it assumes an exp [ − α √ m ] / √ m -form with the break-up being at about the solar mass. Various astrophysical reasonings are given for identifying the exp [ − α m ] and exp [ − α √ m ] / √ m with halo and disk star characteristics, respectively. The physical conditions during the halo formation were such that low mass stars were preferentially formed and those in the disk high mass stars favoured. The two component nature of IMF is in general accord with the dichotomies in various stellar properties.
4,000원
