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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Publications of The Korean Astronomical Society
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The Korean Astronomical Society
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Volume & Issues
Volume 8, Issue 1 - Dec 1993
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CONSTRUCTION OF 21CM COSMIC RADIO ANTENNA
Park, Jong-Ae ; Yang, Jong-Man ; Han, Seok-Tae ; Park, Yong-Seon ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 1~15
We made a pyramidal horn antenna system for 21cm cosmic radio wave. The antenna system has a rectangular waveguide with
mode and a copper probe to detect the electromagnetic wave in waveguide. The parameters of the probe are obtained by experiments using two waveguides. Pyramidal horn antenna is designed to get a gain of 20dB. The size of the aperture of this horn is
. The beam width of half power is about
for the frequency of 1.4GHz. The horn is made of aluminum plate with a thickness of 2mm. The signal from horn and waveguide is amplified in a receiver system and is converted into DC in the detecter. The intensity of the signal is recorded on a chart recorder. We observed the sun using this simple radio telescope and obtained the brightness temperature of
, which indicates that the sun is quiet at 21cm.
SPECTRAL INDICES MEASURED BY PDS ON THE 4 DEGREE OBJECTIVE PRISM PLATE
Lee, Sang-Gak ; Baek, Won-Geun ; Hong, Seung-Su ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 17~31
In order to check whether the 4-degree objective prism spectra can be used for deep spectroscopic studies of galactic structure, we measured the Rose(1984)'s seven indices between 3500 A and 4400 A for 19 Hyades stars on the Kiso Schmidt prism plate, K3496. By comparing the
-indices with those of Rose(1984), we have found that
, and P(3912)/P(CN) measured on the 4-degree prism spectra, are still useful for the derivation physical parameters.
THE EFFECTS OF SCAN SPEED AND APERTURE OF PDS ON THE SPECTRUM ANALYSIS
Lee, Sang-Gak ; O, Seung-Jun ; Kim, Eun-Hyeok ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 33~45
The variation of instrumental profile for the different scan speed of PDS is estimated as FWHM of the assumed Gaussian Profile. The effects of scan speed and scan aperture of PDS on the objective prism spectrum analysis are investigated for 8 combinations of scan speed and scan aperture. Amomg them. D1 apture with 15 csu is found to be the most optimum choice for measuring KISO objective prism film. We suggest the preliminary test study of the scan speed and aperture for the optimum use of PDS for any massive scan of spectra. The optimum scan speed and aperture depends on the dispersion of spectrum as well as the type of phtographic emulsion.
PERFORMANCE TEST OF AUTOMATED PHOTOGRAPHIC PHOTOMETER AND PHOTOMETRY OF CLUSTER BYUR 2
Jo, Dong-Hwan ; Lee, Si-U ; Lee, Hyeon-Gon ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 47~66
The Automated Eichner Iris Photometer(AEIP) at the Korea Basic Science Center was tested for its function and the proper procedure for photographic photometry. The AEIP requires about three hours for reaching the electrical stability. When the iris is controlled automatically, the repeatability of density unit (DU) is accurate in the uncertainty of (
)DU. The iris reading is found to be accurate within the mean error of
, which could be reduced to
by the manual control. To check the applicability of the AEIP. each two photographic plates for UBV colors which were taken by Dupuy and Zukauskas(l976) for the open cluster Byur 2, were measured by using the AEIP. and the photographic magnitudes and colors of the stars in Byur 2 were determined. discussing the previous results.
DEVELOPMENT OF THE REAL-TIME CCD PHOTOMETRIC PROGRAM
Kim, Seung-Ri ; Park, Nam-Gyu ; Pyo, Tae-Su ; Seong, Hwan-Gyeong ; Lee, Si-U ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 67~82
We developed a real-time CCD photometric program for IBM PC compatibles. This program can perform several functions necessary for CCD photometry such as telescope control. filter rotation, CCD camera control and data acquisition, two-dimensional image processing, simple aperture photometry and automatic differential photometry. The image processing of a spiral galaxy M51 observed with the SNU 61cm reflector shows a well developed spiral structure. Simple aperture photometric results of 14 stars in open cluster NGC 6871 almost accorded with those from IRAF/APPHOT. And we could confirm the light variation of eclipsing binary EM Cep by simultaneous automatic differential photometry of 7stars in NGC 7160. Due to the excellence in the precision and efficiency of automatic differential photometry using CCD. this program is very useful for the study of small amplitude
Sct type variables and of the photometric stability of B
F type stars.
INTENSITY VARIATION OF THE SiO MASER LINE OF LONG PERIOD VARIABLES : MASER PUMPING MECHANISM
Kim, Eun-Hyeok ; Lee, Sang-Gak ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 83~104
In principle, both radiation and collision are capable of pumping the SiO masers. In order to check which pumping mechanism is more efficient, we calculated the rate equation for our model including the 3 vibrational slates with 7 rotational states of each vibrational slate. Through solving the radiative transfer equation with the Sovolev approximation, we estimated the line profiles from an expanding envelope for several transitions. It is found that the collision works more efficiently than the radiation for the inversion in excited vibrational stales. However in an expanding envelope model we could not get the strong line intensity as observed one because the population inversion is possible only in a small restricted region. For the enough population inversion to get type observed maser intensity. the number density of SiO and hydrogen molecules should be up to about
, respectively, and the inversion should be occured in the region of no Jess than 11014cm.
IMPROVED ASTRONOMICAL IMAGE REPRODUCING TECHNIQUES
Jeon, Yeong-Beom ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 105~117
Astronomical plates have a very large density range (dynamical range). Many exposed astronomical photographic plates do not provide detailed structures for very high densities, and some include hidden images for very low densities. The former can be fixed through 'Unsharp Masking' technique and the latter through 'Image Amplification' technique. Besides, we can find intrinsic colors of celestial bodies through 'Tri Color Composition' technique. Images of several plates which were observed from Sobaek Observatory with 61cm telescope are reproduced by the three kinds of image reproducing techniques. As reproduced image examples, we display an Orion nebula and a waxing crescent moon images through unsharp masking technique and an M81 image through image amplification technique. An Orion nebula and a Dumbbell nebula images are also given as results of tri color composition technique.
HYPERSENSITIZATION FOR ASTRONOMICAL PHOTOGRAPHIC PLATES: IIIa-J, IIIa-F, 103a-O, 103a-D and IIa-O PLATES
Jeon, Yeong-Beom ; Sim, Gyeong-Jin ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 119~136
Optimum hypering conditions are found for IIIa-J, IIIa-F, 103a-O, 103a-D, and IIa-O plates using hypersensitization machine in KAO. For every experimental plate we get speed gain, fog increment, signal to noise ratio and relative DQE according to hypering time and temperature. The hypersensitization method is baking with 8% hydrogen mixed gas. For IIIa-J, 103a-O, and 103a-D plates treated
, 3 hours baking, the speed gains arc increased by about 10 times, 2 times, and 2 times compared to untreated plates, respectively. The fogs are increased by 0.08, 0.10, and 0.08, respectively. For IIIa-F, IIa-O plates treated
, 2 hours baking, the speed gains are increased by about 4.7 times and 1.8 times compared to untreated plates, respectively. The fogs are increased by 0.15 and 0.04, respectively.
NUMERICAL METHOD FOR THE ASTRONOMICAL ALMANAC AND ORBIT CALCULATIONS
Kim, Gap-Seong ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 137~151
We have calculated the astronomical almanac 1994 and simulated the trajectory of a satellite orbit considering all perturbative forces with various initial conditions. In this work, Gauss Jackson multistep integration method has been used to calculate our basic equation of motion with high numerical accuracy. It has beer. found that our results agree well with the Astronomical Almanac Data distributed by JPL of NASA and the orbit simulations have been carried out with fast speed, stability and excellent round-off error accumulation, comparing with other numerical methods. In order to be carried out our works on almanac and orbit calculations easily by anyone who uses a personal computer, we have made a computer program on graphical user interface to provide various menus for detail works selected by a mouse.
THE RELATIVE SUNSPOT NUMBERS IN 1993
Sim, Gyeong-Jin ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 153~161
We analyze 211 data of the daily sunspot observations during the period of January 4 to November 30 in 1993 and present the daily relative sunspot numbers. During 334 days of the period, the preliminary annual average of the relative sunspot numbers is found to be 61.8 based on 27.1 distinct spots in a single group for 3.7 spot groups. According to the appearance of 203 spot groups, our analysis shows that the mean life time of spot group is about 1 day and 15.5 hours. Our records show that more number of sunspots have appeared in the southern hemisphere than in the northern hemisphere by some 2%, indicating that the solar activities of the northern and southern hemisphere are much the same during the period.
INTRODUCTION TO THE PHYSICS OF ACCRETION DISK
Wheeler, J. Craig ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 163~168
At intermediate mass transfer rates, accretion disks in binary star systems undergo a thermally-driven limit cycle instability. This instability leads to outburst episodes when the disk is bright and the flow through the disk is rapid separated by long intervals when the disk is dim and the flow through it is low. This intrinsic outburst mechanism can help to understand a wide range of astrophysical phenomena from dwarf novae to soft X -ray transients involving white dwarf, neutron star, and black holes. and to a deeper understanding of the mechanism of angular transport and viscosity in the accretion disk.
THE CLASSIFICATION AND PHYSICS OF SUPERNOVAE
Wheeler, J. Craig ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 169~177
Observed spectra of supernovae allow the empirical classification of supernovae into two basic categories, Type I with little or no evidence of hydrogen, and Type II with obvious evidence for hydrogen. The broad class of Type I can be subdivided depending on whether helium or silicon and other intermediate mass elements is observed. Understanding the physical processes that underlie these classifications---the progenitor evolution. the explosion mechanism, and end products---requires calculation of radiative transfer and model spectra. While most Type II occur in evolved massive stars that undergo core collapse. some may span the dividing line between degenerate and non-degenerate carbon burning and involve both core collapse and thermonuclear explosion. Type Ia are still most plausibly explained as thermonuclear explosions in carbon/oxygen white dwarfs in binary systems. Type Ib reveal helium atmospheres and are probably the result of core collapse in the helium core of a massive star that has lost its hydrogen envelope to a binary companion or to a wind. Type Ic supernovae are probably related to Type Ib but have also lost their helium envelope to reveal a mantle rich in oxygen.
EVOLUTION OF ACTIVE GALACTIC NUCLEI BASED ON THE UNIFIED THEORY
Park, Seok-Jae ; Vsihniac, Ethan T. ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 179~183
We analyze the evolution of active galactic nuclei for the decreasing accretion rate case. Our analysis is based on the unified theory of active galactic nuclei which entirely depends on the accretion rates of the central supermassive black holes. Our discussion leads us to conclude that active galactic nuclei may evolve from QSOs into the nuclei of Seyfert or radio galaxies.
DEVELOPMENT OF AN AUTOMATIZED DIFFERENTIAL PHOTOMETRY SYSTEM FOR THE 61CM REFLECTOR OF SOBAEKSAN OBSERVATORY
Park, Nam-Gyu ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 185~197
We developed an Automatized Differential Photometry System (ADPS) to achieve high time resolution and high efficiency in the photometric observations of short period variable stars. This ADPS has been introduced to the CCD camera system attached to the 6lcm Reflector at Sobaeksan Astronomy Observatory. Several new algorithms were devised for the controlling the telescope. the star recognition in a CCD frame and the aperture photometry, etc..As the result, the differential photometric observation was fully automatized without any manual control, and much faster data acquisition could be achieved over the conventional photoelectric differential photometry.
HOT GAS IN ELLIPTICAL GALAXIES
Kim, Dong-Woo ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 199~206
We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of
and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.
북한의 천문학 교육 및 연구현황 분석연구
Min, Yeong-Gi ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 207~241
A STUDY ON THE STELLAR PHYSICAL PARAMETERS
Lee, Sank-Gak ; Kim, Ke-Young ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 243~263
One hundred forty two digital spectra of 110 standard stars with 1 A resolution in
region were analyzed to determine the spectral indices sensitive to the atmospheric parameters. The standard stars cover the temperature in the range of
and the surface gravity in the range of log g from 0 to 5 and the metal abundance [Fe/H] from -2.7 to 0.4. We have derived physical parameters, theta(=T/5040), log g, and [Fe/H] for the standard stars using indices, P(38/93), Fe I(A), Fe I(B), SrII, and
, with overall accuracies of 0.067, 0.617, and 0.466, respectively. However for some region of spectral type and metallicity, those can be obtained with better accuracies. Those indices are found to be useful especially for stellar gravity determination.
ELECTRON-POSITRON PAIRS IN ACCRETION DISKS
Shin, Mine-Shige ; Kusunose, Masaaki ;
Publications of The Korean Astronomical Society, volume 8, issue 1, 1993, Pages 265~272
Recent X-ray observations of the accretion disks in stellar black hole candidates have revealed rather complex behavior, which cannot be fully described by the simple picture of the standard disk model. In this paper, therefore, we discuss the effects of e+e- pair creation on the structure and the stability of hot accretion disks, aiming at the thorough understanding of emission properties of X-ray binaries containing black holes.