간행물
천문학논총 KCI 등재 Publications of the Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 연3회
- ISSN 1225-1534 (Print)2287-6936 (Online)
- 수록기간 1984 ~ 2024
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권호리스트/논문검색
Volume 8 (1993년 12월) 18건
1.
1993.12
구독 인증기관 무료, 개인회원 유료
We made a pyramidal horn antenna system for 21cm cosmic radio wave. The antenna system has a rectangular waveguide with TE10 TE10 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 94cm×74cm 94cm×74cm . The beam width of half power is about 14.7∘ 14.7∘ 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 2.2×105K 2.2×105K , which indicates that the sun is quiet at 21cm.
4,800원
2.
1993.12
구독 인증기관 무료, 개인회원 유료
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 4∘ 4∘ -indices with those of Rose(1984), we have found that Hδ/FeI Hδ/FeI , Hγ/4325 Hγ/4325 , and P(3912)/P(CN) measured on the 4-degree prism spectra, are still useful for the derivation physical parameters.
4,800원
3.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,500원
4.
1993.12
구독 인증기관 무료, 개인회원 유료
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 (0.0028∼0.0048 0.0028∼0.0048 )DU. The iris reading is found to be accurate within the mean error of 0.m05 0.m05 , which could be reduced to 0.m02 0.m02 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.
5,500원
5.
1993.12
구독 인증기관 무료, 개인회원 유료
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 δ δ Sct type variables and of the photometric stability of B ∼ ∼ F type stars.
4,900원
6.
1993.12
구독 인증기관 무료, 개인회원 유료
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 2×105cm−3 2×105cm−3 and 1×109cm−3 1×109cm−3 , respectively, and the inversion should be occured in the region of no Jess than 11014cm.
5,800원
7.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,500원
8.
1993.12
구독 인증기관 무료, 개인회원 유료
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 65∘C 65∘C , 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 65∘C 65∘C , 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.
5,200원
9.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,800원
10.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
11.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
12.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
13.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
14.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,500원
15.
1993.12
구독 인증기관 무료, 개인회원 유료
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 ∼0.8keV ∼0.8keV and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.
4,000원
16.
1993.12
구독 인증기관 무료, 개인회원 유료
본 연구에서는 북한에서 발행된 출판물을 통해서 북한의 천문학 교육과 연구 현황을 조사 분석하고 이를 남한의 실상과 비교하였다. 북한에는 국가 천문대로서 과학원 소속의 평양천문대가 있다. 이 천문대의 시설은 연구보라는 주로 실용성의 천문 관측을 위한 것들이다. 북한에는 교육용천문대로서 김일성종합대학 천문대, 평양학생소년궁전 천문대, 만경대소년궁전 천문대가 있다. 북한에서는 천문학 교육이 초등학교에서 대학까지 광범위하게 이루어지고 있지만 천체현상의 원리를 이해시키기보다는 현상의 설명에 치우치고 있다. 김일성 종합대학에서 천문학자가 양성되고 있으나 독립된 학과는 없고 물리학과에서 천문학 교육을 담당하고 있다. 남북한의 용어에는 상당한 차이가 나타나고 있다. 북한 용어의 특징은 우리말로 풀어서 만든 용어가 맡은 것이다. 북한에는 천문학의 단독학술지는 없고 단행본의 수도 극히 적다. 북한에서 발표되는 연구논문의 수는 매년 수편에 불과하다. 북한의 역서는 천문력과 항해력을 합친 것으로 방대한 분량을 수록하고 있다. 출판물에 나타난 북한의 천문학자수는 42명이고 그들 중 21명이 국채전문연맹 회원으로 등록되어 있다. 북한학자들은 천문학의 기초 분야보다는 태양 관련 분야나 위치천문, 인공위성 등 실생활과 관련 있는 연구를 주로 하고 있다. 앞으로 남북 교류가 이루어진다면 남한의 기초와 북한의 응용 분야가 결합해서 상호 보완적으로 천문학 수준 향상을 이룩할 수 있을 것으로 기대된다.
8,300원
17.
1993.12
구독 인증기관 무료, 개인회원 유료
One hundred forty two digital spectra of 110 standard stars with 1 A resolution in λλ3000A∼4150A λλ3000A∼4150A region were analyzed to determine the spectral indices sensitive to the atmospheric parameters. The standard stars cover the temperature in the range of Teff Teff from ∼4000∘ ∼4000∘ to ∼7000∘K ∼7000∘K 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 Hδ Hδ , 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.
5,700원
18.
1993.12
구독 인증기관 무료, 개인회원 유료
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.
4,000원
