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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 51/122
501
- FENG LONG-LONG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.129-133
- 2005
- 원문 바로보기
The temperature (T) and entropy (S) fields of baryonic gas, or intergalactic medium (IGM), in the ACDM cosmology are analyzed using simulation samples produced by a hybrid cosmological hydrodynamic/N-body code based on the weighted essentially non-oscillatory scheme. We demonstrate that, in the nonlinear regime, the dynamical similarity between the IGM and dark matter will be broken in the presence of strong shocks in the IGM. The heating and entropy production by the shocks breaks the IGM into multiple phases. The multiphase and non-Gaussianity of the IGM field would be helpful to account for the high-temperature and high-entropy gas observed in groups and clusters with low-temperature IGM observed by Ly<TEX>$\alpha$</TEX> forest lines and the intermittency observed by the spikes of quasi-stellar object's absorption spectrum.
502
- NISHIOKA HIROAKI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.175-178
- 2005
- 원문 바로보기
We show that next-generation galaxy surveys such as KAOS (the Kilo-Aperture Optical Spectro-graph)will constrain dark energy even if the baryon oscillations are missing from the monopole power spectrum and the bias is scale- and time-dependent KAOS will accurately measure the quadrupole power spectrum which gives the leading anisotropies in the power spectrum in redshift space due to peculiar velocities, the finger of God effect, as well as the Alcock-Paczynski effect. The combination of monopole and quadrupole power spectra powerfully breaks the degeneracy between the bias parameters and dark energy and, in the complete absence of baryon oscillations (<TEX>$\Omega$</TEX>b = 0), leads to a roughly <TEX>$500\%$</TEX> improvement in constraints on dark energy compared with the monopole spectrum alone. As a result, for KAOS the worst case with no oscillations has dark energy errors only mildly degraded relative to the ideal case, providing insurance on the robustness of KAOS constraints on dark energy. We show that nonlinear effects are crucial in correctly evaluating the quadrupole and significantly improving the constraints on dark energy when we allow for multi-parameter scale-dependent bias.
503
- Kyeong, Jae-Mann
- Journal of the Korean astronomical society = 천문학회지
- 38, n.4
- pp.415-422
- 2005
- 원문 바로보기
UBVIJHK photometry of the open cluster NGC 2194 are presented. Color-Magnitude diagrams of this cluster show well-defined main sequence and red giant clump. The main sequence also contains clear evidence of binary populations. Based on color-color diagrams, absolute magnitude of red giant clump, ZAMS fitting, and comparisons of observed color-magnitude diagrams with theoretical models, we derive following parameters for the cluster; reddening <TEX>$E(B-V)=0.44{\pm}0.04$</TEX>, age of log <TEX>$t{\sim}8.8$</TEX>, and finally distance of <TEX>$(m-M)_0=12.20{\pm}0.18$</TEX>.
504
- SATO SHUJI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.107-108
- 2005
- 원문 바로보기
The situations and locations of the Asian astronomical observatories are overviewed. I propose to construct a medium size Infrared Telescope at a good site in the Asian district.
505
- YANAGISAWA KENSHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.109-112
- 2005
- 원문 바로보기
We present the design, expected performance, and current status of the wide field near-infrared camera (OAOWFC) now being developed at Okayama Astrophysical Observatory, NAOJ, NINS. OAOWFC is a near-infrared survey telescope whose effective aperture is 91cm. It works at Y, J, H, and <TEX>$K_s$</TEX> bands and is dedicated to the survey of long period variable stars in the Galactic plane. The field of view is <TEX>$0.95 {\times} 0.95 deg^2$</TEX> which is covered by one HAWAII-2 RG detector of 2048 <TEX>${\times}$</TEX> 2048 pixels with the pixel size of <TEX>$18.5 {\mu}m\;{\times}\;18.5{\mu}m$</TEX>, that results in the sampling pitch of 1.6 arcsec/pixel. OAOWFC can sweep the area of <TEX>$840 deg^2$</TEX> every 3 weeks, attaining a limiting magnitude of 13 in <TEX>$K_s$</TEX> band. It allows us to observe long period variables embedded in the Galactic plane where interstellar extinction is severe in optical.
506
- YAO YONGQIANG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.113-116
- 2005
- 원문 바로보기
The program of site survey in western China has been initiated by the National Astronomical Observatories of China(NAOC) toward large telescope facilities. The program is carried out in aspects of remote studies and local surveys. The preliminary results show that the eastern Pamirs and Ali area in Tibet may be the best candidates for further monitoring. The site survey group of NAOC will proceed to set up site testing stations on the selected sites and perform monitoring and campaign in 2005.
507
- MATSUSHITA SATOKI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.169-172
- 2005
- 원문 바로보기
We present CO(3-2), CO(2-1), and 230 GHz (1.3 mm) continuum images of nearby galaxies taken with the Submillimeter Array (SMA). Our main topic is to study the relation between higher-J molecular gas (e.g., CO J=3-2, 2-1) and nuclear activities (e.g., active galactic nuclei [AGNs] and starbursts). The nearby Seyfert 2 galaxy M51 shows strong CO(3-2) emission from the circumnuclear molecular gas, with an intensity twice as strong as that of the CO(1-0) emission. Strong CO(3-2) emission enhancement suggests that the circum nuclear molecular gas in M51 is warm and dense, which may be related to the AGN activities. Molecular gas in the nearby moderate starburst galaxy NGC 6946 is distributed along the large-scale bar or spiral arms and along the minibar, and the multi-J CO line images show very similar distribution to each other. For this galaxy, there is no clear enhancement in higher-J lines as seen in M51, which may be because NGC 6946 does not have clear AGN activities. Based on the results of these two galaxies, the physical conditions of the circum nuclear molecular gas may be related to the AGN activities. We also observed the nearby edge-on starburst galaxy NGC 3628 and the starburst/Seyfert composite galaxy NGC 4945 with the CO(2-1) line and 230 GHz (1.3 mm) continuum emission. These information will give us some hints for understanding the relation between nuclear activities and circum nuclear molecular gas and dust.
508
- KIM SUNGEUN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.223-226
- 2005
- 원문 바로보기
We present the results of a 21cm radio continuum aperture synthesis mosaic of the Large Magellanic Cloud (LMC), made by combining data from 1344 separate pointing centers using the Australia Telescope Compact Array (ATCA) and the 64-m Parkes single-dish telescope. The resolution of the mosaicked images is 55' ( 10 pc, using a distance to the LMC) and a region <TEX>$10^{\circ}{\times}12^{\circ}$</TEX> is surveyed.
509
- MURATA YASUHIRO
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.97-100
- 2005
- 원문 바로보기
The first Space-VLBI project, VSOP, started successfully with the launch of the dedicated space-VLBI satellite HALCA in 1997. The project has been in scientific operation in the 1.6 GHz and 5 GHz bands, and studies have been done mainly of the jet phenomena related to active galactic nuclei. A second generation space- VLBI project, VSOP-2, has been planned by the working group formed at ISAS/JAXA with many collaborators. The spacecraft is planned to observe in the 8, 22 and 43 GHz bands with cooled receivers for the two higher bands, and with a maximum angular resolution at 43 GHz (7 mm) of about 40 micro-arcseconds. The VSOP-2 satellite will also have the capability of the phase-reference and full polarization observations, which will produce more powerful results than those of the VSOP project. Far-future space-VLBI projects following VSOP and VSOP-2, have a large potential to achieve enough resolution and sensitivity to satisfy astronomers in future.
510
- LEE JOUNGHUN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.161-164
- 2005
- 원문 바로보기
We present a theoretical formalism by which the global and the local mass functions of dark matter substructures (dark subhalos) can be analytically estimated. The global subhalo mass function is defined to give the total number density of dark subhalos in the universe as a function of mass, while the local subhalo mass function counts only those sub halos included in one individual host halo. We develop our formalism by modifying the Press-Schechter theory to incorporate the followings: (i) the internal structure of dark halos; (ii) the correlations between the halos and the subhalos; (iii) the subhalo mass-loss effect driven by the tidal forces. We find that the resulting (cumulative) subhalo mass function is close to a power law with the slope of <TEX>${\~}$</TEX> -1, that the subhalos contribute approximately <TEX>$10\%$</TEX> of the total mass, and that the tidal stripping effect changes the subhalo mass function self-similarly, all consistent with recent numerical detections.