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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 50/122
491
- CHUNG EUN JUNG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.1
- pp.17-22
- 2005
- 원문 바로보기
In this paper, we suggest a new referencing method for the array On-The-Fly(OTF) observations in radio astronomy. To reduce the baseline residual, we have proposed and evaluated a new referencing method which uses the source free regions in the observed frame as references. These new references have small <TEX>${\Delta}$</TEX>t and <TEX>${\Delta}$</TEX>x, the time and position differences between the source and the references, and the systematic problems w~re improved by using this new referencing method. The curved baseline residuals were straightened and the rms was reduced to 17 mK. This new referencing method is expected not only to make possible to take more stable data for the array OTF observation of external galaxies but also to save the observation and data reduction time.
492
- ZHOU Xu
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.203-206
- 2005
- 원문 바로보기
The large field multi-color CCD sky survey program based on the 60/90 Schmidt telescope of NAOC has been processed in cooperation among many observatories and universities of Asian countries. The observation and scientific results are reviewed.
493
- Lee, Ho-Gyu
- Journal of the Korean astronomical society = 천문학회지
- 38, n.4
- pp.385-414
- 2005
- 원문 바로보기
We have searched for infrared emission from supernova remnants (SNRs) included in the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) field. At the positions of 100 known SNRs, we made 3.6, 4.5, 5.8, and <TEX>$8.0{\mu}m$</TEX> band images covering the radio continuum emitting area of each remnant. In-depth examinations of four band images based on the radio continuum images of SNRs result in the identification of sixteen infrared SNRs in the GLIMPSE field. Eight SNRs show distinct infrared emission in nearly all the four bands, and the other eight SNRs are visible in more than one band. We present four band images for all identified SNRs, and RGB-color images for the first eight SNRs. These images are the first high resolution (<2') images with comparative resolution of the radio continuum for SNRs detected in the mid-infrared region. The images typically show filamentary emission along the radio enhanced SNR boundaries. Most SNRs are well identified in the 4.5 and <TEX>$5.8{\mu}m$</TEX> bands. We give a brief description of the infrared features of the identified SNRs.
494
- SUH KYUNG-WON
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.267-270
- 2005
- 원문 바로보기
We investigate the spectral energy distributions (SEDs) of low mass-loss rate O-rich asymptotic giant branch (AGB) stars using the infrared observational data including the Infrared Space Observatory (ISO) data. Comparing the results of detailed radiative transfer model calculations with observations, we find that the dust formation temperature is much lower than 1000 K for standard dust shell models. We find that the superwind model with a density-enhanced region can be a possible alternative dust shell model for LMOA stars.
495
- WANG YUN-CHING
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.299-302
- 2005
- 원문 바로보기
Sprites, elves and blue jets are collectively denominated as the upper atmospheric transient luminous events (TLEs). They are recently discovered optical flashes between active thunderstorms and the ionosphere. In this report, a brief introduction to the most important characteristics of TLEs is given. Since 2001, scientists from the National Cheng Kung University have been performing yearly summer campaigns from various locations in Taiwan. The main achievements of their yearly campaign are presented.
496
- Kim Sang-Chul
- Journal of the Korean astronomical society = 천문학회지
- 38, n.4
- pp.429-435
- 2005
- 원문 바로보기
We present BV CCD photometry for the open clusters Czernik 24 and Czernik 27. These clusters have never been studied before, and we provide, for the first time, the cluster parameters; reddening, distance, metallicity and age. Czernik 24 is an old open cluster with age <TEX>$1.8{\pm}0.2Gyr$</TEX>, metallicity <TEX>$[Fe/H]=-0.41{\pm}0.15dex$</TEX>, distance modulus <TEX>$(m-M)_0=13.1{\pm}0.3mag$</TEX> (<TEX>$d=4.1{\pm}0.5kpc$</TEX>), and reddening <TEX>$E(B-V)=0.54{\pm}0.12mag$</TEX>. The parameters for Czernik 27 are estimated to be <TEX>$age=0.63{\pm}0.07Gyr$</TEX>, <TEX>$[Fe/H]=-0.02{\pm}0.10dex$</TEX>, <TEX>$(m-M)_0=13.8{\pm}0.2mag$</TEX> (<TEX>$d=5.8{\pm}0.5kpc$</TEX>), and <TEX>$E(B-V)=0.15{\pm}0.05mag$</TEX>. The metallicity and distance values for Czernik 24 are consistent with the relation between the metallicity and the Galactocentric distance of other old open clusters. We find the metallicity gradient of 51 old open clusters including Czernik 24 to be <TEX>${\Delta}[Fe/H]/{\Delta}R_{gc}=-0.064 {\pm}0.009dex\;kpc^{-1}$</TEX>.
497
- KOMIYA ZEN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.157-160
- 2005
- 원문 바로보기
To constrain the values of the model parameters for the cosmological models involving the time-decaying <TEX>$\Lambda$</TEX> term, we have computed sets of theoretical predictions for the N-m relation of galaxies as well as the CMB angular power spectrum: three types of variation, viz., <TEX>${\Lambda}{\propto} T^{-1},\;a^{-m}$</TEX>, and <TEX>$H^n$</TEX> are thereby assumed following Overduin & Cooperstock (1998), although we concentrate here on the discussion of the results obtained from the first type. Our results for the N-m relation indicate that the observed excess of the galaxy counts N in the faint region beyond the blue apparent magnitude 24 can be reasonably well accounted for with the value of <TEX>${\iota}$</TEX> in the range between 0.2 and 1. Furthermore, a comparison of our computational results of the CMB spectra with the observational data shows that the models with a mild degree of the <TEX>$\Lambda$</TEX> term decay, viz., with the value of <TEX>${\iota}{\le}$</TEX>0.4, are favorable. In this case, the age of our universe turns out to be larger than or equal to 14 Gyr, the lower limit inferred from some Uranium datings.
498
- 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.
499
- 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.
500
- 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.