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- 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
- 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.
502
- 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.
503
- 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.
504
- 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.
505
- MAKINO JUNICHIRO
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.165-168
- 2005
- 원문 바로보기
We overview the GRAPE (GRAvity piPE) project. The goal of the GRAPE project is to accelerate the astrophysical N-body simulations. Since almost all computing time is spent for the evaluation of the gravitational force between particles, we can greatly accelerate many N-body simulations by developing a specialized hardware for the force calculation. In 1989, the first such hardware, GRAPE-1, was completed, with the peak speed of 120 Mflops. In 2003, GRAPE-6 was completed, with the peak speed of 64 Tflops, which is nearly 106 times faster than GRAPE-l and was the fastest computer at that time. In this paper, we review the basic concept of the GRAPE hardwares, the history of the GRAPE project, and two ongoing projects, GRAPE-DR and Project Milkyway.
506
- 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.
507
- YAO YONGQIANG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.335-336
- 2005
- 원문 바로보기
The working group for an infrared telescope(IRT) toward East Asian Observatory has been set up in EAMA6. This report declares the membership of IRT working group, reviews briefly the activities of promoting the IRT, and puts forward the future plan.
508
- 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.
509
- KAWASAKI WATARU
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.141-144
- 2005
- 원문 바로보기
Based on optical galaxy data, we executed a systematic search for galaxy clusters around the 15 steady unidentified EGRET GeV gamma-ray sources in high Galactic-latitude sky ([b] > <TEX>$30^{\circ}$</TEX>). We found a strong correlation with 3.7<TEX>$\sigma$</TEX> level between close cluster pairs (merging cluster candidates) and the unidentified EGRET sources, though, in contrast, no correlation with single clusters. This result implies that merging clusters of galaxies are a possible candidate for the origin of high galactic-latitude, steady unidentified EGRET gamma-ray sources.
510
- CHEN YANG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.211-214
- 2005
- 원문 바로보기
We performed a spatially resolved spectroscopic study of the thermal composite supernova remnant 3C 391 by the Chandra observation. Broad- and narrow-band X-ray images show a southeast-northwest elongated morphology and unveil a highly clumpy structure of the remnant. The spectral analysis for. the small-scale features indicates normal metal abundance and uniform temperature for the interior gas. The properties of the hot gas are largely in agreement with the cloudlet evaporation model as a main mechanism for the 'thermal composite' X-ray appearance, though radiative rim and thermal conduction may also be effective. An unresolved X-ray source, with a power-law spectrum, is observed on the northwest border. The equivalent width images reveal a faint finger-like protrusion in Si and S lines out of the southwest radio border.