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- The Korean Astronomical Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-4614 (ISSN : 1225-4614)
1225-4614
- DB구축현황 : 1,227건 (DB Construction : 1,227 Articles)
총 게시글 1,227건
페이지 83/123
821
- KIM SUNGEUN
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.95-95
- 1996
- 원문 바로보기
We present the recent results of an HI 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). The resolution of the mosaiced images is 1'.0 (15 pc, using a distance to the LMC of 50 kpc). In contrast with its appearance at other wavelengths, the LMC is remarkably symmetric in HI on the largest scales, with the bulk of the HI residing in a disk of diameter 7.3 kpc. Outer spiral structure is clearly seen, though the features appear due to differential rotation, therefore transient in nature. A good correlation is seen between the supershells previously identified in Halpha (e.g. Meaburn 1980) and HI structures.
822
- KIM YONGGI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.247-248
- 1996
- 원문 바로보기
In order to study the X-ray radiations from solar type strong interacting binary stars, we have collected X-ray data of 44i Bootis (P=0.2678 days, SP=G2+G2) from the EXOSAT data archive. Preliminarly analysis of a part of these data has been already reported by Vilhu & Heise (1986). In this paper, however, we present a more complete light curve in LE region than the previous work, and some unpublished X-ray light curves and spectrums. Using these new materials a new attempt to find the physical explanation about. some observational characteristic figures in the X-ray light curves and spectrums has been made.
823
- CHOE G. S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.303-305
- 1996
- 원문 바로보기
The evolution of solar magnetic arcades is investigated with the use of MHD simulations imposing resistivity on sheared magnetic fields. It is found that there is a critical amount of shear, over which magnetic reconnection can take place ill an arcade-like field geometry to create a magnetic island. The process leading to reconnect ion cannot. be solely attributed to a tearing instability, but rather to a reactive evolution of the magnetic arcade under resistivity. The natures of the arcade reconnection are governed by the spatial pattern of resistivity. A fast reconnection with a small shock angle can only be achieved when the diffusion region is localized. In this case. a highly collimated reconnect ion outflow can tear the plasmoid into a pair, and most of principal features in solar eruptive processes are reproduced.
824
- KRAICHEVA ZDRAVKA
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.227-228
- 1996
- 원문 바로보기
The long-term light curves of the novalikes TT Ari, KR Aur, AM Her and MV Lyr, were compiled and analysed for solar-like cyclical behaviour. The frequency analysis showed long-term cyclical modulations of the brightness of the stars, which can be ascribed to changes of the radii of the late type secondaries in order of <TEX>${\Delta}R/R{\simeq} 10^{-4}-10^{-5}$</TEX>.
825
- ITOH NOBUNARI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.379-380
- 1996
- 원문 바로보기
We have constructed a near-infrared imaging camera which is attached to the prime focus of 105cm Schmidt telescope at Kiso Observatory. The camera is equipped with a 1040<TEX>$\times$</TEX>1040 PtSi CSD array developed by Mitsubishi Electric Co. The combination of Kiso Schmidt and the array gives a wide field of view of 18.4'<TEX>$\times$</TEX>18.4' with a reasonable spatial resolution of 1.06' /pixel. The system performances of the camera have been evaluated through laboratory and observational tests. Low noise, good cosmetics(no defect pixels), and good stability of the camera system show an excellent performance for astronomical use.
826
- TOMITA AKIHIKO
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.71-72
- 1996
- 원문 바로보기
We show that the star formation activity of spiral galaxies has a great variety. The star formation variation in a time scale of <TEX>$10^8$</TEX> yr and the mechanism responsible for the variation are discussed.
827
- LEE HYUN-CHUL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.133-134
- 1996
- 원문 바로보기
We present the systematic variations of H<TEX>$\beta$</TEX> index of simple stellar populations due to horizontal-branch (HB) stars. Most of the previous works have been done without careful considerations of HB stars. Since the Balmer line strengths are very sensitive to the temperature, including the HB stars are quite important. We found that the strength of H,6 index is strongly affected by HB stars, and hence the age estimation without careful consideration of the variation of HB morphology with metallicity and age would underestimate the ages of ellipticals.
828
- ZHOU WENGE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.403-404
- 1996
- 원문 바로보기
This paper describes a plan of a new IR phace-shfting interferometric system for testing astronomical aspheric mirror which has big departure from the best fit reference sphere during fine grinding. In this experimental system, some new technology will be adopted. The accuracy of system can reach <TEX>$\lambda$</TEX>/40(<TEX>$\lambda$</TEX>=10.6<TEX>${\mu}m$</TEX>)
829
- LEE SANG WOO
- Journal of the Korean astronomical society = 천문학회지
- 29, n.1
- pp.9-18
- 1996
- 원문 바로보기
We have analyzed vector magnetograms and <TEX>$H\beta$</TEX> filtergrams of two sunspot groups, one in a growing phase and the other in a decaying phase. In this study, the temporal evolution of their magnetic morphology has been investigated in association with solar activity. The morphological variations of the growing and decaying phase of these sunspots revealed in detail the coalescence of small spots into a large spot and the fragmentation of a large spot into many small spots, respectively. Numerous small flares were detected in the spot group during the decaying phase. This seems to be intimately associated with the shearing motions of many spots with different polarities created by fragmentation of a large sunspot. The magnetic flux and the average shear angle are found to be substantially reduced during the decaying phase, especially in the course of the flarings. This implies that the decaying phase of the sunspot is, to some degree, involved with magnetic field cancellation. The growing spot group has not shown any large activities, but numerous small spots have grown into a typical bipolar sunspot.
830
- XIAO K. C.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.413-414
- 1996
- 원문 바로보기
A 230 GHz SIS tunnel junction receiver has been being developed for radio astronomy in Nagoya University. In this heterodyne receiver, we use a <TEX>$\~$</TEX>1/3 reduced hight rectangular waveguide SIS mixer with two tuning elements as front end. The mixer block with SIS junction was cooled to 4K with a closed cycle He-gas refrigerator. So far, a double sideband receiver noise temperature lower than l00K in 222-237 GHz is obtained. The receiver exhibits a best DSB noise temperature of 69K at 236 GHz as well as 228 GHz.