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
제29권 제S호 (1996년 12월) 178건
1.
1996.12
구독 인증기관 무료, 개인회원 유료
Recent discussions of observational constraints on the standard hot big bang model are reviewed and it is argued that now there is room for considering alternative cosmologies. The quasi-steady state cosmology is briefly described. This model seems to explain most of the observed features of the universe, including the m-z relation, radio source count, the light nuclear abundances and the microwave background.
4,000원
2.
1996.12
구독 인증기관 무료, 개인회원 유료
With an interim calibration based upon half the Key Project's galaxies, the Tully-Fisher relation, the (Dn, σ) relation and type II supernovae yield H0= 73 ± 10 km/sec/Mpc.
3,000원
3.
1996.12
구독 인증기관 무료, 개인회원 유료
Super-inflation driven by dilaton/moduli kinetic energy is naturally realized in compactified string theory. Discussed are selected topics of recent development in string inflationary cosmology: kinematics of super-inflation, graceful exit triggered by quantum back-reaction, and classical and quantum power spectra of density and metric perturbations.
3,000원
4.
1996.12
구독 인증기관·개인회원 무료
We discuss the possible ranges of electron neutrino degeneracy which is consistent with the inferred primordial abundances of the light elements. It is found that the electron neutrino degeneracy, |ℇe|, up to order of 10 -1 is consistent with the present data.
5.
1996.12
구독 인증기관·개인회원 무료
COBE's results on the anisotropy of the cosmic microwave background radiation (CMBR) is discussed. Some ambiguities in the linear GI cosmic perturbation theory are clarified. The problem of the last scattering surface and the deficiencies of the linear cosmic perturbation theory are mentioned. The possible ways to overcome the theoretical difficulties are discussed also.
6.
1996.12
구독 인증기관 무료, 개인회원 유료
We apply topological measures of clustering such as percolation and genus curves (PC & GC) and shape statistics to a set of scale free N-body simulations of large scale structure. Both genus and percolation curves evolve with time reflecting growth of non-Gaussianity in the N-body density field. The amplitude of the genus curve decreases with epoch due to non-linear mode coupling, the decrease being more noticeable for spectra with small scale power. Plotted against the filling factor GC shows very little evolution - a surprising result, since the percolation curve shows significant evolution for the same data. Our results indicate that both PC and GC could be used to discriminate between rival models of structure formation and the analysis of CMB maps. Using shape sensitive statistics we find that there is a strong tendency for objects in our simulations to be filament-like, the degree of filamentarity increasing with epoch.
3,000원
7.
1996.12
구독 인증기관·개인회원 무료
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 (Ω0 = 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 Ω0 = 1 universe. We also found that the model is more likely to fit these data in a cosmological constant dominated (Λ-) universe.
8.
1996.12
구독 인증기관·개인회원 무료
In the standard theory of the large scale structure formation, matter accretes onto high density perturbations via gravitational instability. Collision less dark matter forms caustics around such structures, while collisional baryonic matter forms accretion shocks which then halt and heat the infalling gas. Here we discuss the characteristics. roles, and observational consequences of these accretion shocks.
9.
1996.12
구독 인증기관 무료, 개인회원 유료
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.
3,000원
10.
1996.12
구독 인증기관 무료, 개인회원 유료
The role of gravitational lenses as valuable tools for astrophysics and cosmology is highlighted.
3,000원
11.
1996.12
구독 인증기관 무료, 개인회원 유료
Much of our knowledge about the formation and evolution of high-redshift galaxies has come from studying the absorption signatures they impress on the spectra of background QSOs. The damped Lyman α (DLA) systems, in particular, have proved to be valuable probes of the metallicity and dust at redshifts z ~2-3 in what are the likely progenitors of galaxies like our own. At z ~ 2 we find that the typical metallicity of the universe was 1/15 solar. In addition, we find clear evidence for the existence of trace amounts of interstellar dust in DLA galaxies and show that this is consistent with recent high resolution spectra of DLAs with the Keck telescope, despite claims to the contrary.
3,000원
12.
1996.12
구독 인증기관·개인회원 무료
Using the Keck 10 m telescope data with the HIRES spectrograph, we analyzed the evolution of Lymanα forest clouds at z > 2 down to the HI column density 10 12.8cm -2. The number density per unit column density does not change with redshifts at lower HI cloumn density (NHI < 10 14cm-2), 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.
13.
1996.12
구독 인증기관·개인회원 무료
A possible cosmic X-ray background(XRB) radiation related to original antimatter is considered. If the universe is made of separating domains of antimatter and matter, the photons produced by the annihilation of electron-positron and proton-antiproton on the last scattering surface would reach us in the energy ~0.45 keV and ~60 keV respectively because of the redshift. The spectrums of X-ray radiation from annihilation are deduced and a possible observational figure is described also.
14.
1996.12
구독 인증기관·개인회원 무료
15.
1996.12
구독 인증기관 무료, 개인회원 유료
Rings are common in disk galaxies. These rings are either indistinguishable from a pair of tightly wound spirals, or themselves are a part of the spiral structure. Furthermore, their occurrence is seen coincident with a bar in the center. In this paper, we interpret this spiral-ring structure as density waves resonantly excited by a rotating bar potential. The theory gives excellent agreement for the molecular spiral-rings in central parts. of nearby disk galaxies, observed by high resolution radio arrays. The same mechanism works for more distant spiral-rings in the outer parts of disk galaxies qualitatively, although the problem is complicated by the coupling of the stellar and gaseous disks.
3,000원
16.
1996.12
구독 인증기관 무료, 개인회원 유료
New population synthesis models, with the effects of metallicity spread and the horizontal-branch (HB) morphology, provide a way to break the well-known age-metallicity degeneracy in the analysis of the integrated light of elliptical galaxies. Our models suggest that the far- UV radiation of these systems is dominated by a minority population of metal-poor, hot HB stars and their post-HB progeny, while the optical radiation is dominated by a metal-rich population. The systematic variation of UV upturn depends on the contribution from metal-poor, hot HB stars and their post-HB progeny, which in turn depends on the ages of old stellar populations in galaxies. Our result implies a prolonged epoch of galaxy formation, in the sense that more massive galaxies (in denser environments) formed first. Our models also suggest that the strenghth of Hβ index is strongly affected by HB stars, and hence previous age estimation without detailed modeling of the HB would underestimate the ages of ellipticals by ~7 Gyr.
3,000원
17.
1996.12
구독 인증기관·개인회원 무료
Based on the database of 128 disk galaxies (66 SO, 62 S and Irr) mailnly compiled from Kent and Gunn (1982) and Doi et a1.(1995) which is complete down to m < 15.6 mag within a radius of 3°, the orientation of spin vectors of disk galaxies of the Coma cluster has been analyzed. The results confirm the morphological dependence of the orientation of disk galaxies found from the analsis of the Virgo cluster. Common features of orientation of disk galaxies of both clusters are outlined.
18.
1996.12
구독 인증기관·개인회원 무료
In order to investigate the spatial orientation of the spin vectors of galaxies in the Virgo cluster, we carried out a detailed identification of all the certain and possible member disk galaxies with four UK Schmidt Telescope (UKST) III a-j direct plates digitized by the Automated Plate Measuring System (APM). As a result, a relatively large and complete database with no selection effect of the member galaxies has been established. We provide the APM measured values of the position angle (P.A.) and diameters at the isophotal level of 24.5 mj / arcsec2. Based on this newly generated database, an initial study on the spatial orientation of the spin vectors of galaxies in the Virgo cluster is shown.
19.
1996.12
구독 인증기관·개인회원 무료
There is an excess gamma flux from the general direction of the Galactic North Pole compared with that from the south when allowance is made for the contribution from CR interactions with the HI gas (Osborne et al., 1994). The extent to which it is in accord with the predictions of Wdowczyk and Wolfendale (1990 a,b) for gamma rays secondary to very high energy CR escaping from the VIRGO cluster is examined and it is claimed that the observations may well be of the order of those expected.
20.
1996.12
구독 인증기관·개인회원 무료
