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1968년 ~ 2023년까지 1,187 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 : 1,187건 (DB Construction : 1,187 Articles)
총 게시글 1,187건
페이지 83/119
821
- WATANABE TETSUYA
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.291-294
- 1996
- 원문 바로보기
The .Japanese sun observing satellite, Yohkoh, has been operational for five years and her scientific instruments are still in good condition. They have revealed ample of evidences that solar flares were triggered by magnetic reconnection, which was, for the first time, clearly indicated to take place in the solar corona. Cusp structures in soft X-rays and a new type of hard X-ray sources at the top of flaring loops have strongly supported the scenario originally proposed by C-S-H-KP. Nonthermal energy input in hard X-rays and thermal energy estimated from soft X-rays are fundamentally consistent with the interpretation of thick-target and chromospheric-evaporation models (Neupert effect). X-ray jets, another discovery of Yohkoh, were also associated with magnetic reconnection, as a result of the interaction of emerging fluxes with pre-existing coronal loops. Temperature structures of active regions, quiet sun, and coronal holes had very dynamic differential-emission-measure (DEM) distributions and high-temperature tails of DEM were considered to come from the contribution of flare-like activity.
822
- LEE GEUNHO
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.459-460
- 1996
- 원문 바로보기
823
- Xu WENLI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.399-400
- 1996
- 원문 바로보기
LAMOST is a special reflecting Schmidt telescope. Both the refleting Schmidt plate <TEX>$M_A$</TEX> and the spherical primary mitrror <TEX>$M_B$</TEX> are segmened mirrors. These two cofocus but not co-phase. The diffraction of the optical system is decided by the shape overlapping of <TEX>$M_A$</TEX> and <TEX>$M_B$</TEX>. This paper describes the diffraction caculating results with different declination and different field angle. The diffraction influence to the image quality is acceptable in the error buget of optical system. It also proves that the size seletion of the sub-mirror is reasonable.
824
- ALMLEAKY Y. M.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.317-319
- 1996
- 원문 바로보기
Utilizing a Calcium filter, a large two ribbon flare of an importance 2.5Xj31? was recorded at. King Abdul-Aziz University Solar Observatory (KAAUSO) at the 30th of October 1991. This chromosphenc flare observation, which is of special importance since it is rarely reported, was for a flare that occurred near the south west of the equator at the vicinity of a large sunspot group on an active region known as AR 6891. The observed foot points of this flare had a strange behavior in which the separating motion of the ribbons were not typical of most flares, rather were nearly orthogonal. In this article we present the characteristics of the main sunspot group of this active region and try to investigate its evolution and fragmentation with time. Information regarding magnetic fields and velocity fields are necessary to understand the restructuring of the magnetic field pattern and plasma motion, and hence the changes that could lead to the occurrence of such an interesting flare.
825
- TAKAHARA FUMIO
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.99-102
- 1996
- 원문 바로보기
I discuss implications of gamma-ray emission from blazars based on electron acceleration by shock waves in a relativistic jet. The number spectrum of electrons turns out to be a broken power law; while at low energies the power law index has a universal value of 2, at high energies it steepens to an index of 3 because of strong radiative cooling. This spectrum can basically reproduce the observed spectral break between X-rays and gamma-rays. I show that energetics of relativistic jets can be well explained by this model. I estimate physical quantities of the relativistic jets by comparing the prediction with observations. The results show that the jets are particle dominated and are comprised of electron-positron pairs. A connection between gamma-ray emission and radiation drag is also discussed.
826
- KIM JONG BOCK
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.15-16
- 1996
- 원문 바로보기
We discuss the possible ranges of electron neutrino degeneracy which is consistent with the inferred primordial abundances of the light elements. It is found that the electron neutrino degeneracy, [<TEX>${\epsilon}_e$</TEX>], up to order of <TEX>$10^{-1}$</TEX> is consistent with the present data.
827
- XU CHONGMING
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.17-18
- 1996
- 원문 바로보기
COBE's results on the anisotropy of the cosmic microwave background radiation (CMBR) is discussed. Some ambiguities in the linear GI cosmic perturbation theory are clarified. The problem of the last scattering surface and the deficiencies of the linear cosmic perturbation theory are mentioned. The possible ways to overcome the theoretical difficulties are discussed also.
828
- PARK BYEONG-GON
- Journal of the Korean astronomical society = 천문학회지
- 29, n.1
- pp.63-73
- 1996
- 원문 바로보기
The previous study of chemical evolution of the Galaxy is extended to the radial properties of the Galactic disk. The present model includes radial dependency of the time-dependent bimodal IMF, radial flow of material in the disk, and the change of type I supernova explosion rate with radial distance from the disk center as model parameters and observed gas and stellar density distributions and metallicity abundance gradient as observational constraints. The results of two models in this study explain the observed gas and stellar density distributions well, with the slope of the gas density gradient in the region of 4.5 kpc<r<12kpc as -0.136dex/kpc in model <TEX>$Y_1$</TEX> and -0.123dex/kpc in model <TEX>$Y_2$</TEX>, respectively, which fit well the observed gradient of -0.l1dex/kpc. The abundance gradient reproduced in model <TEX>$Y_1$</TEX> is getting flatter with decreasing radius, while that in model <TEX>$Y_2$</TEX> is getting steeper, which fits better the observed abundance gradient. This result shows the necessity of exponentially increasing type I supernova explosion rate with decreasing radius in order to explain the observed abundance gradient in the disk. The fitness of observed density distribution and star formation rate distribution justifies the reliability of time-dependent bimodal IMF as a compound quantitative chemical evolution model of the Galaxy. The temporal variations of metallicity gradients for carbon, nitrogen and oxygen are also shown.
829
- MATSUHARA H.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.171-172
- 1996
- 원문 바로보기
We present the results of an rocket-borne observation of far-infrared [CII] line at 157.7 <TEX>${\mu}m$</TEX> from the diffuse inter-stellar medium in the Ursa Major. We also introduce a part of results on the [CII] emission recently obtained by the IRTS, a liquid-helium cooled 15cm telescope onboard the Space Flyer Unit. From the rocket-borne observation we obtained the cooling rate of the diffuse HI gas due to the [CII] line emission, which is <TEX>$1.3{\pm}0.2 {\times} 10^{-26}$</TEX> <TEX>$ergss^{-1} H^{-1}_{atom}$</TEX>. We also observed appreciable [CII] emission from the molecular clouds, with average CII/CO intensity ratio of 420. The IRTS observation provided the [CII] line emission distribution over large area of the sky along great circles crossing the Galactic plane at I = <TEX>$50^{\circ}$</TEX> and I = <TEX>$230^{\circ}$</TEX>. We found two components in their intensity distributions, one concentrates on the Galactic plane and the another extends over at least <TEX>$20^{\circ}$</TEX> in Galactic latitude. We ascribe one component to the emission from the Galactic disk, and the another one to the emission from the local interstellar gas. The [CII] cooling rate of the latter component is <TEX>$5.6 {\pm} 2.2 {\times}10$</TEX>.
830
- BROSCH NOAH
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.421-423
- 1996
- 원문 바로보기