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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 73/122
721
- JUNG JAE HOON
- Journal of the Korean astronomical society = 천문학회지
- 34, n.3
- pp.157-166
- 2001
- 원문 바로보기
The molecular cloud associated with the H II region S301 has been mapped in the J = 1-0 transitions of <TEX>$^{12}CO$</TEX> and <TEX>$^{13}CO$</TEX> using the 13.7 m radio telescope of Taeduk Radio Astronomy Observatory. The cloud is elongated along the north-south direction with two strong emission components facing the H II region. Its total mass is <TEX>$8.7 {\times} 10^3 M{\bigodot}$</TEX>. We find a velocity gradient of the molecular gas near the interface with the optical H II region, which may be a signature of interaction between the molecular cloud and the H II region. Spectra of CO, CS, and HCO+ exhibit line splitting even in the densest part of the cloud and suggests the clumpy structure. The radio continuum maps show that the ionzed gas is distributed with some asymmetry and the eastern part of the H II region is obscured by the molecular cloud. We propose that the S301 H II region is at the late stage of the champagne phase, but the second generation of stars has not yet been formed in the postshock layer.
722
- 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.
723
- DWARKADAS VIKRAM V.
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.243-246
- 2001
- 원문 바로보기
We summarize various aspects of the interaction of supernova remnants (SNRs) with the ambient medium. We discuss the evolution' of SNRs in environments sculpted by the progenitor star, and summarize the factors on which this evolution depends. As a specific example, we consider the evolution of the medium around a 35 M<TEX>$\bigodot$</TEX> star, and the interaction of the shock wave with this medium when the star explodes as a SN. We also discuss the interaction of Type Ia SNe with the ambient medium, especially the formation and growth of hydrodynamic instabilities.
724
- ISOBE HIROAKI
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.337-339
- 2001
- 원문 바로보기
One-dimensional hydrodynamic modeling of a protostellar flare loop is presented. The model consists of thermally isolated loop connecting the central core and the accretion disk. We found that the conductive heat flux of a flare heated the accretion disk up to coronal temperature and consequently the disk is evaporated and disappeard. This effect may explain the ovserved feature of the repeated flare from the young stellar object YLW 15.
725
- KIM HUN-DAE
- Journal of the Korean astronomical society = 천문학회지
- 34, n.3
- pp.167-179
- 2001
- 원문 바로보기
A molecular line survey towards the UC H II region G34.3+0.15 from 155.3 to 165.3GHz has been conducted with the TRAO 14-m radio telescope. Combined with our previous observations from 84.7 to 115.6GHz and 123.5 to 155.3GHz (Paper I), the spectral coverage of this survey in G34.3+0.15 now runs from 85 to 165 GHz. From these latest observations, a total of 18 lines from 6 species were detected. These include four new lines corresponding to <TEX>${\Delta}$</TEX>J = 0, <TEX>${\Delta}$</TEX>K = 1 transitions of the <TEX>$CH_3OH$</TEX> E-type species, and two new lines corresponding to transitions from <TEX>$SO_2$</TEX> and <TEX>$HC_3N$</TEX>. These 6 new lines are <TEX>$CH_3OH$</TEX>[1(1) - 1(0)E], <TEX>$CH_3OH$</TEX>[2(1) - 2(0)E], <TEX>$CH_3OH$</TEX>[3(1) - 3(0)E], <TEX>$CH_3OH$</TEX>[4(1) - 4(0)E], <TEX>$SO_2$</TEX>[14(1, 13) -14(0, 14)] and <TEX>$HC_3N$</TEX>[18 -17]. We applied a rotation diagram analysis to derive rotation temperatures and column densities from the methanol transitions detected, and combined with NRAO 12-m data from Slysh et al. 1999. Applying a two-component fit, we find a cold component with temperature 13-16K and column density <TEX>$3.3-3.4 {\times} 10^{14} cm^{-2}$</TEX>, and a hot component with temperature 64 - 83K and column density <TEX>$9.3{\times}10^{14} - 9.7 {\times} 10^{14} cm^{-2}$</TEX>. On the other hand, applying just a one-component fit yields temperatures in the 47 -62 K range and column densities from <TEX>$7.5-1.1 {\times} 10^{15} cm^{-2}$</TEX>.
726
- 문봉곤
- Journal of the Korean astronomical society = 천문학회지
- 34, n.1
- pp.35-40
- 2001
- 원문 바로보기
For the planned experiments of Korea Sounding Rocket-III (KSR-III), we have constructed a model of MUV dayglow in the mid-latitude. The model computes relative intensities of individual emission lines in the Vegard-Kaplan and 2PG band systems of <TEX>$N_2$</TEX> in the wavelength range of 2500-3500<TEX>${\AA}$</TEX>. In addition to the emission lines, solar scattered continuum was computed by an extended LOWTRAN7 code, in which we have included solar scattering in altitudes higher than 100 km by using MSIS90 thermosphere model. Ratios among vibrational bands of VK and 2PG system, were computed from the observed MUV dayglow spectra of Cleary et al. (1995). The model provides MUV dayglow intensitiy profiles with a wavelength resolution of 3.13<TEX>${\AA}$</TEX> as a function of altitude. The computed intensity profiles have been utilized in designing the KSR-III airglow photometers.
727
- 한수련
- Journal of the Korean astronomical society = 천문학회지
- 34, n.2
- pp.67-80
- 2001
- 원문 바로보기
Chemical evolution of galaxies can be understood by studying the spatial distribution of heavy elements. We selected two nearby galaxies, M31 and M33 and investigated spectrum of their HII regions: a) the elec-tron densities have been derived from the [S II] 6717/6731 ratio along with the most recent atomic constants (Hyung & Aller 1996); b) the electron temperatures were determinated from the Pagel's empirical method. Nebula Model (Hyung 1994) has been employed to predict the spectral line intensities which gives the proper chemical abundances. The model would predict the line intensities correctly only when various input parameters such as the effective central star temperatures, gravity log g, model atmosphere as well as the geometry and the nebula physical condition are appropriate. Thus, the determination of chemical abundances of O, S, N of the two nearby galaxies M31 and M33 has been done, which shows a radial dependance of O/H and N/H: decrease with the distance, or increasing electron temperature due to the elemental deficiency. Abundances of M31 appear to be enhanced than those of M33.
728
- KOVALENKO ILYA G.
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.271-273
- 2001
- 원문 바로보기
We present a 4-parameter implicit Lagrangean code which satisfies conservation of mass, linear and angular momenta, energy and entropy simultaneously. The primary advantage of this scheme is possibility to control dissipative properties of the scheme avoiding the effects of numerical viscosity.
729
- MATHEWS GRANT J.
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.265-269
- 2001
- 원문 바로보기
We present preliminary numerical simulations of tilted-disk accretion around a rotating black hole. Our goal is to explore whether hydrodynamic instabilities near the Bardeen-Petterson radius could be responsible for generating moderate-frequency quasi-periodic oscillations in X-ray binaries. We review the relevant general relativistic hydrodynamic equations, and discuss preliminary results on the structure and dynamics of a thin, Keplerian disk.
730
- KIM JONGSOO
- Journal of the Korean astronomical society = 천문학회지
- 34, n.4
- pp.333-335
- 2001
- 원문 바로보기
We study the properties of supernova (SN) driven interstellar turbulence with a numerical magnetohydrodynamic (MHD) model. Calculations were done using the RIEMANN framework for MHD, which is highly suited for astrophysical flows because it tracks shocks using a Riemann solver and ensures pressure positivity and a divergence-free magnetic field. We start our simulations with a uniform density threaded by a uniform magnetic field. A simplified radiative cooling curve and a constant heating rate are also included. In this radiatively-cooling magnetized medium, we explode SNe one at a time at randomly chosen positions with SN explosion rates equal to and 12 times higher than the Galactic value. The evolution of the system is basically determined by the input energy of SN explosions and the output energy of radiative cooling. We follow the simulations to the point where the total energy of the system, as well as thermal, kinetic, and magnetic energy individually, has reached a quasi-stationary value. From the numerical experiments, we find that: i) both thermal and dynamical processes are important in determining the phases of the interstellar medium, and ii) the power index n of the <TEX>$B-p^n$</TEX> relation is consistent with observed values.