모달창 닫기
- 홈으로 이동
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 71/122
701
- KYEONG JAE-MANN
- Journal of the Korean astronomical society = 천문학회지
- 34, n.3
- pp.143-147
- 2001
- 원문 바로보기
UBVI CCD photometry of open cluster NGC 2324 is presented. C-M diagrams of this cluster show well-defined main sequence with a red giant clump centered at B - V =1.05, V =13.45. We derived the major cluster characteristics; E(B - V)=0.17<TEX>$\pm$</TEX>0.12 from color-color diagram and mean color of red giant clump stars, (m - M)o=13.1<TEX>$\pm$</TEX>0.1 from zero age main sequence fitting, and [Fe/H]<TEX>$\~$</TEX>-0.32 from comparison the theoretical model developed by Bertelli et al. (1994) to the observed C-M diagrams. We estimate the age of NGC 2324 to be log t<TEX>$\~$</TEX>8.8 by applying isochrone fitting and morphological age index method.
702
- 유계화
- Journal of the Korean astronomical society = 천문학회지
- 34, n.1
- pp.31-33
- 2001
- 원문 바로보기
The collision effects in particles of the accretion disk are examined by the use of small perturbation. The collision force is assumed to be equal to 2 vV. From the equations governing collisions of such particles the local dispersion relation is obtained.
703
- ALLEN ANTHONY
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.325-327
- 2001
- 원문 바로보기
This poster summarizes numerical collapse calculations of non-rotating and rotating singular, isothermal toroids that employed the zeus2d (Norman and Stone 1992) magnetohydrodynamics package. In the non-rotating collapse calculations, it is seen that infall proceeds at a constant rate and magnetically supported, high density pseudo-disks form in the equatorial plane. With rotating clouds, however, toroidal magnetic fields grow as infall proceeds, teaming with angular momentum to slow the inflow to the center and generate outflow.
704
- KYEONG JAE-MANN
- Journal of the Korean astronomical society = 천문학회지
- 34, n.3
- pp.137-141
- 2001
- 원문 바로보기
We derive a new relationship between the giant branch slope as measured in the color-magnitude diagram (K, J - K) and [Fe/H] metallicity for old open clusters. Previously such relationships have been derived for globular clusters, while similar tendency has been expected for open clusters. New derived correlation, [Fe/H]=-17.2(<TEX>$\pm$</TEX>0.23)GB slope - 1.95(<TEX>$\pm$</TEX>0.02), is based on a collection of data for 10 old open clusters. Most clusters behave as expected from the theoretical predictions.
705
- ANN H. B.
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.261-263
- 2001
- 원문 바로보기
Numerical simulations based on the smoothed particle hydrodynamics (SPH) is performed to investigate the dynamical properties of barred galaxies that have nuclear rings. The nuclear ring morphology depends on the relative strength of bar potentials. Nuclear rings form between the two ILRs and align perpendicular to the bars unless the bar potentials are strong enough to allow the x1 orbits near the ILRs. Shock dissipation plays a critical role in the formation of nuclear rings.
706
- FUX ROGER
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.255-259
- 2001
- 원문 바로보기
PMDSPH is a combined 3D particle-mesh and SPH code aimed to simulate the self-consistent dynamical evolution of spiral galaxies including live stellar and collisionless dark matter components, as well as an isothermal gas component. This paper describes some aspects of this code and shows how its application to the Milky Way helps to recover the gas flow within the Galactic bar region from the observed HI and CO longitude-velocity distributions.
707
- KOIDE SHINJI
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.215-224
- 2001
- 원문 바로보기
We present the whole basis of numerical method and useful formulae for general relativistic magnetohydrodynamic simulations in Kerr space-time.
708
- KANG HYESUNG
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.293-295
- 2001
- 원문 바로보기
A numerical scheme that incorporates a self-consistent cosmic-ray (CR, hereafter) injection model into the combined gas dynamics and CR diffusion-convection code has been developed. The hydro/CR code can follow in a very cos-effective way the evolution of CR modified shocks by adopting subzone shock-tracking and multi-level Adaptive Mesh Refinement techniques. The injection model is based on interactions of the suprathermal particles with self-generated MHD waves in quasi-parallel shocks. The particle injection is followed numerically by filtering the diffusive flux of suprathermal particles across the shock to upstream region according to a velocity-dependent transparency function, which represents the fraction of leaking suprathermal particles. In the strong shock limit of Mach numbers <TEX>$\ge$</TEX>20, significant physical processes such as the injection and acceleration seem to become independent of M, while they are sensitively dependent on M for M < 10. Although some particles injected early in the evolution continue to be accelerated to higher energies, the postshock CR pressure reaches a time asymptotic value due to balance between acceleration and diffusion of the CR particles.
709
- LEE HYESOOK
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.321-323
- 2001
- 원문 바로보기
Compressible, magnetohydrodynamic (MHD) turbulence in two dimension is studied through high-resolution, numerical simulations with the isothermal equation of state. First, hydrodynamic turbulence with Mach number <TEX>$(M)_{rms}\;\~$</TEX>1 is generated by enforcing a random force. Next, initial, uniform magnetic field of various strengths with Alfvenic Mach number Ma <TEX>$\gg$</TEX> 1 is added. Then, the simulations are followed until MHD turbulence is fully developed. Such turbulence is expected to exist in a variety of astrophysical environments including clusters of galaxies. Although no dissipation is included explicitly in our simulations, truncation errors produce dissipation which induces numerical resistivity. It mimics a hyper-resistivity in our second-order accurate code. After saturation, the resulting flows are categorized as SF (strong field), WF (weak field), and VWF (very weak field) classes respectively, depending on the average magnetic field strength described with Alfvenic Mach number, <TEX>$(Ma)_{rms}{\ge}1$</TEX>, <TEX>$(Ma)_{rms}{\~}1$</TEX>, and <TEX>$(Ma)_{rms}{\gg}1$</TEX>. The characteristics of each class are discussed.
710
- SHYUE KEH-MING
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.237-241
- 2001
- 원문 바로보기
Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.