모달창 닫기
- 홈으로 이동
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 85/122
841
- KIM SEUNG-LEE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.1
- pp.31-41
- 1996
- 원문 바로보기
We present results of time-series CCD photometry for 178 stars in the young open cluster M29 (=NGC6913). Total 1036 V-band CCD frames were collected for five nights between August 12 and September 13, 1994. The photometric precision is about 7.6 mmag for 9th-10th mag stars in M29 with exposure times of 30 seconds. From the dispersion diagram and the light curves, one detached eclipsing binary (HD194378) and two suspected variables are newly discovered. <TEX>$A\;\gamma\;Cas$</TEX> type variable, V1322 Cyg, which has been known as a member of M29, did not show any light variations during the period of present observations, indicating that it passed the steady phase without the eruption during our observing runs.
842
- CHEN ROSIE CHANG-HUI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.135-136
- 1996
- 원문 바로보기
We present a new photometric study of the globular cluster NGC288 in Stromgren u, v, b, y, and H<TEX>$\beta$</TEX> system. This cluster is known to have an intermediate metallicity but its color-magnitude diagram has a pure blue horizontal branch, which is a signature of metal poor stellar population. We compare our dataset with Bergbusch's (1993) in both field size and CMD to see whether different photometry system would determine the same physical parameters of a cluster. Demarque and Yi's isochrones (1996, private communication) were applied to Bergbusch's dataset, and we obtained distance modulus of (m - M) = 14.9 <TEX>$\pm$</TEX> 0.2, color excess of E(B - V) = 0.03, and age of 1.5<TEX>$\pm$</TEX>3 Gyr. Vandenberg's (1985) isochrones for Stromgren system were also applied to Bergbusch's and our data. We find that the isochrone fits to different photometric systems give rather in consist ant solutions. The source of this discrepancy may become clear when the Demarque and Yi's isochrones for Johnson system are converted to those of Stromgren system. We note that Kurucz model atmospheres provide a useful ground for this conversion work as well as theoretical study of Stromgren characteristics of globular cluster stars.
843
- SUBRAMANIAN K.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.155-158
- 1996
- 원문 바로보기
Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic dynamo. Both options have difficulties: There is no known battery mechanism for producing the required primordial field. Equally the turbulent dynamo may self destruct before being able to produce the large scale field, due to excess generation of small scale power. The current status of these difficulties is discussed. The resolution could depend on the nature of the saturated field produced by the small scale dynamo. We argue that the small scale fields do not fill most of the volume of the fluid and instead concentrate into intermittent ropes, with their peak value of order equipartition fields, and radii much smaller than their lengths. In this case these fields neither drain significant energy from the turbulence nor convert eddy motion of the turbulence on the outer scale to wave like motion. This preserves the diffusive effects needed for the large scale dynamo operation.
844
- KIM BONG GYU
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.193-194
- 1996
- 원문 바로보기
A large scale <TEX>$^{13}CO$</TEX>(J=1-0) survey was made for CMa OB1/R1 region in <TEX>$220^{\circ}{\le}{\iota}{\le}230^{\circ}$</TEX> and <TEX>$-10^{\circ}{\le}b{\le}10^{\circ}$</TEX> with a 8' spacing by using the 4 m radio telescope of Nagoya University. 34 isolated clouds were identified in this survey. Among them, two clouds were firstly identified by us. The observed LSR velocity indicate that almost of the all clouds are located in the Local arm, except two extreme velocity. The mass spectrum of the clouds in the Local arm is best fitted by a power-law index of 1.6.
845
- 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.
846
- LEE GEUNHO
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.459-460
- 1996
- 원문 바로보기
847
- 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.
848
- 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.
849
- 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.
850
- 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.