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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 84/123
831
- 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.
832
- FATEMI S. J.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.57-58
- 1996
- 원문 바로보기
There is an excess gamma flux from the general direction of the Galactic North Pole compared with that from the south when allowance is made for the contribution from CR interactions with the HI gas (Osborne et al., 1994). The extent to which it is in accord with the predictions of Wdowczyk and Wolfendale (1990 a,b) for gamma rays secondary to very high energy CR escaping from the VIRGO cluster is examined and it is claimed that the observations may well be of the order of those expected.
833
- LEE YOUNGUNG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.187-188
- 1996
- 원문 바로보기
We have mapped <TEX>$1 deg^2$</TEX> region toward a high latitude HII region S73 (l, b) = (<TEX>$37^{\circ}.69$</TEX>, <TEX>$44^{\circ}.55$</TEX>) and associated molecular cloud in <TEX>$^{12}CO$</TEX> J = 1 - 0, and <TEX>$^{13}CO$</TEX> J = 1 - 0, using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory. A high resolution autocorrelator is used to resolve extremely narrow CO linewidths (FWHP < 1 km/s) of the molecular cloud. Though the linewidths are very narrow, it is found that there is systematic velocity gradient in the molecular gas associated with the H II region. Both of <TEX>$^{12}CO$</TEX> and <TEX>$^{13}CO$</TEX> averaged spectra are non-gaussian, and there are obvious blue wings in the spectra. It is remarkable that the linewidths at the blueshifted region are broader than those of the rest of the cloud. The CO emission does match well with the dust emission.
834
- HU HUI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.255-256
- 1996
- 원문 바로보기
835
- 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.
836
- 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)
837
- CHAKRABARTI SANDIP K.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.281-282
- 1996
- 원문 바로보기
838
- 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.
839
- 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.
840
- 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.