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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 80/122
791
- FANG C.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.295-298
- 1996
- 원문 바로보기
Non-LTE calculations, with the non-thermal ionization effects included, indicated that for electron bombardment, the H<TEX>$\alpha$</TEX> line is widely broadened and shows a strong central reversal. Significant enhancements at the line wings of Ly<TEX>$\alpha$</TEX> and Ly<TEX>$\beta$</TEX> are also predicted at the beginning of the impulsive phase of flares. For the proton bombardment, no strong broadening and no large central reversal are expected. However, due to proton-hydrogen charge exchange, the enhancements at the red wings of Ly<TEX>$\alpha$</TEX> and Ly<TEX>$\beta$</TEX> lines at the early impulsive phase of flares are significant. Our results show that the electron beam can also in some cases generate visible and UV continuum emission in white-light flares. However, at the onset phase, a negative flare may appear within several seconds, due to the increase of the H- opacity. Another spectroscopic signature of energetic particles, i.e. the impact polarization of atomic lines, is also mentioned.
792
- YUAN CHI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.45-48
- 1996
- 원문 바로보기
Rings are common in disk galaxies. These rings are either indistinguishable from a pair of tightly wound spirals, or themselves are a part of the spiral structure. Furthermore, their occurrence is seen coincident with a bar in the center. In this paper, we interpret this spiral-ring structure as density waves resonantly excited by a rotating bar potential. The theory gives excellent agreement for the molecular spiral-rings in central parts. of nearby disk galaxies, observed by high resolution radio arrays. The same mechanism works for more distant spiral-rings in the outer parts of disk galaxies qualitatively, although the problem is complicated by the coupling of the stellar and gaseous disks.
793
- OKAMURA S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.375-378
- 1996
- 원문 바로보기
An outline is given of our development of mosaic CCD cameras. Hardware and data reduction software of two operational cameras are described. Scientific objectives of wide-field imaging with the cameras are briefly described.
794
- KASINSKY V. V.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.315-316
- 1996
- 원문 바로보기
Based on X-ray (1-8 <TEX>${\AA}$</TEX>) flux data for 1972-1995 the integral spectra of solar flare energy were computed. It has been shown that the spectral index <TEX>$\beta$</TEX> of the integral energy spectrum (IES) vanes systematically with the 11-year cycle phase. The interval of <TEX>$\beta$</TEX>-variations (0.47 <<TEX>$\beta$</TEX><1) is characteristic of UV-Cet stars. The maximum energy of the X-ray flares does not exceed <TEX>$10^{32}$</TEX> erg.
795
- SUNG EON-CHANG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.87-88
- 1996
- 원문 바로보기
796
- CHANG KYONG-AE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.1
- pp.1-8
- 1996
- 원문 바로보기
When we follow the lines of the trajectory of photons which intersect the circle, the circle may suffer some deformation as approaching to the observer. We consider an infinitesimal light bundle suffering gravitational bending. We examine the deformation of the deflected light bundle due to the gravitational lens. The size of the deformation is expressed in terms of the focal length of the gravitational lens.
797
- CHAKRABARTI SANDIP K.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.281-282
- 1996
- 원문 바로보기
798
- TOHMURA ICHIROH
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.333-335
- 1996
- 원문 바로보기
Here we report the results from spectroscopic observations of soloar active regions in the HeI 10830 <TEX>${\AA}$</TEX> line at the German Vacuum Tower Telescope(VTT) in Tenerife during the August 199:3 International EFR(Emerging Flux Region) Campaign. Four active regions in various stages of their evolution, i.e., NOAA7558, 7560, 7561, and 7562, were ovserved on 10 August 1993. From the observed HeI 10830 <TEX>${\AA}$</TEX> spectra in these active regions, spectroscopic quantities such as equivalent width(EW), doppler shift, doppler width, etc., were derived(see Figure l(a)) and the correlation between them were studied(see Figure l(b)). Our main results are as follows: (I)In NOAA7562, which is a young and evolving EFR, the EW is large, while it is small around a simple and roundish spot of NOAA7558. (2)In these active regions, redshift in the 10830 line is dominant when the EW is larger. (3)As the doppler width increases, the line tends to shift redward. (4)When the EW is smaller, it seems to exist another component which have dynamic characteristics different from the redshifting component. In NOAA7560 and NOAA7561, regions which have several small spots, the values of the EW are intermediate. Results (2) and (3) may suggest the possible existence of downflow above active regions, if the HeI 10830 <TEX>${\AA}$</TEX>line is formed in the upper chromopshere, and it is consistent with the earlyer result from the SMM extreme-ultraviolet observation by Klimchuk(1987, Astrophys. J., 323, 368) (to be submitted. to Astronomy and Astrophysics; an extended abstract)
799
- MARKELOV S. V.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.387-388
- 1996
- 원문 바로보기
The principles to attain improved accuracy in a new controller for large CCD and mosaics detectors with the application of 16- and 32-bit DSP are presented.
800
- HAN WONYONG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.389-390
- 1996
- 원문 바로보기
The CCDs are widely used in astronomical observations either in direct imaging use or spectroscopic mode. However, the areas of available sensors are too small for large imaging format. One possibility to obtain large detection area is to assemble mosaics of CCD, and drive them simultaneously. Parallel driving of many CCDs together rules out the possibility of individual tuning; however, such optimisation is very important, when the ultimate low light level performance is required, particularly for new, or mixed devices. In this work, a new concept is explored for an entirely novel approach, where the drive waveforms are multiplexed and interleaved. This simultaneously reduces the number of leadout connections and permits individual optimisation efficiently. The digital controller can be designed within a single EPLD (Erasable Programmable Logic Device) chip produced by a CAD software package, where most of the digital controller circuits are integrated. This method can minimise the component. count., and improve the system efficiency greatly, based on earlier works by Han et a1. (1996, 1994). The system software has an open architecture to permit convenient modification by the user, to fit their specific purposes. Some variable system control parameters can be selected by a user with a wider range of choice. The digital controller design concept allows great flexibility of system parameters by the software, specifically for the compatibility to deal with any number of mixed CCDs, and in any format, within the practical limit.