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 ~ 2023
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권호리스트/논문검색
Volume 13 (1998년 12월) 17건
1.
1998.12
구독 인증기관 무료, 개인회원 유료
A quantitative analysis has been made to estimate the horizontal variation of physical parameters in a loop type active prominence by analyzing Call H&K and Hε… Hε… spectra taken from such an active prominence (appeared on May 23, 1981 with position angle 251 degree) with Littrow type spectrograph attached to 25cm coronagraph at Norikura Coronal Station of National Astronomical Observatory of Japan. The spectral resolution is 1.12A/mm and the spatial resolution is 25'/mm for Call H&K lines. The present study shows that the turbulent velocity ranges from 10km/s to 20 km/s in the loop prominence, which are in good agreement with those of Hirayama (1989). It is also found that the temperature of the loop prominence is higher than that of quiescent prominences(\~8,000K) (\~8,000K) by about 4,000 K, whose temperature deviation seems very high.
4,900원
2.
1998.12
구독 인증기관 무료, 개인회원 유료
To study kinematics of solar prominences, we have made Ha spectrographic study of an eruptive prominence which appeared on the 27th of August, 1992 with a position angle of 270 deg. The observation was carried out by a Littrow type spectrograph and a G1 CCD camera attached to the 25cm coronagraph at Norikura Coronal Station. In taking the spectral data the slit was placed in parallel to the solar limb at 7 different heights, each being separated by 5 arcsec with a time step of 30 sec. The observed eruptive prominence shows a wide range of line of sight Doppler velocity, spanning from Vdopp=−17.5km/stoVdopp=58.2km/s Vdopp=−17.5km/stoVdopp=58.2km/s . It is also found that the velocity increases with height at the rate of ΔV=0.86km/s/arcsec ΔV=0.86km/s/arcsec .
4,600원
3.
1998.12
구독 인증기관 무료, 개인회원 유료
The size of fine structures in the quiescent prominence that appeared on August 16, 1992 has been estimated using power spectra generated from intensity variations of Ha images of the lower part of the prominence, which were taken with a G1 CCD camera attached to 25cm coronagraph at Norikura Coronal Station in Japan. The lower part of the prominence has shown a distinct intensity variation with optical thickness of τ=1~5. Our analysis yields a mean size of fine structures ranging from 350 km to 1,000 km, in good agreement with Hirayama(1985) and Zirker & Koutchmy(1989, 1991).
4,000원
4.
1998.12
구독 인증기관 무료, 개인회원 유료
We have developed solar observational system in the department of Astronomy & Space Sciences of KyungHee University, in order to monitor solar activities and construct solar database for space weather forecasting at maximum of 23rd solar cycle, as well as an solar education and exercise for undergraduate students. Our solar observational system consists of the full disk monitoring system and the regional observation system for H a fine structure. Full disk monitoring system is made of an energy rejection filter, 16cm refractor, video CCD camera and monitor. Monitored data are recorded to VHS video tape and analog output of video CCD can be captured as digital images by the computer with video graphic card. Another system for regional observation of the sun is made of energy rejection filter, 21cm Schmidt-Cassegrain reflector, H a filter with 1.6A pass band width and 375×242 375×242 CCD camera. We can observe H a fine structure in active regions of solar disk and solar limb, by using this system. We have carried out intense solar observations for a test of our system. It is found that Quality of our H a image is as good as that of solar images provided by Space Environmental Center. In this paper, we introduce the basic characteristics of the KyungHee Solar Observation System and result of our solar observations. We hope that our data should be used for space weather forecasting with domestic data of RRL(Radio Research Laboratory) and SOFT(SOlar Flare Telescope).
4,900원
5.
1998.12
구독 인증기관 무료, 개인회원 유료
We have analyzed 255 data of the daily sunspot observations during the period of January 3 to December 31 in 1997 and present the daily relative sunspot numbers. During the 1997, the preliminary annual average of the relative sunspot numbers found to be 28.2 based on 9.7 distinct spots in a single group for 1.4 spot groups. According to the appearance of 366 spot groups, our analysis shows that the mean life time of spot group is about 4 day and 17.0 hours.
4,000원
6.
1998.12
구독 인증기관 무료, 개인회원 유료
We installed windscreen at the BOAO 1.8m telescope dome, in order to reduce the degradation of image Quality under strong wind larger than 8m/sec. The windscreen was designed on the basis of that installed at the MSSSO 2.3m telescope dome in Australia. We developed control system (remote control and user program) of the windscreen, being able to operate the windscreen at observation room. We tested the performance of the windscreen under strong wind of 6-15m/see. Tracking error of the telescope, especially in altitude-axis, was greatly decreased when the windscreen was used. Standard deviation of the error was estimated to be less than 0.3arcsec, which has little effect on image quality.
4,000원
7.
1998.12
구독 인증기관 무료, 개인회원 유료
We present the development of a remote observation system runnig on world wide web (WWW). The system consists of a 30cm Schmidt Cassegrain telescope and ST-7 CCD camera. We built the controllers and drivers of the telescope and the control softwares including the network control. The self-developed techniques in the hard wares and softwares can be applied to other projects in Korea. Observers can access the system via WWW home page, to reserve observation times, to send control commands, to retrieve images and various information useful for observation. This system can be widely used by students and amateur astronomers as well as professional astronomers who need a lot of small telescope time.
4,000원
8.
1998.12
구독 인증기관 무료, 개인회원 유료
In this paper we describe MS-TCS, the telescope control system which was developed in Korea Astronomy Observatory. MS-TCS can control an equatorial type telescope equipped with stepping motors and incremental type optical encoders. MS-TCS consists of (1) POINT_TEL which is the program roning in a PC and (2) TCS-196 which is the electroics board to control the telescope. The communication between the PC and TCS-l96 is done through RS-232 or RS-422 serial line. MS-TCS can control the secondary mirror and dome. It also provide network function using TCP/IP for remote control of the telescope. MS-TCS is suitable for controlling medium to small size telescope for research and education.
4,600원
9.
1998.12
구독 인증기관 무료, 개인회원 유료
Korea Astronomy Observatory (KAO) recently developed a new model of CCD imaging system for astronomical purpose. This paper presents system structure and electrical circuit descriptions with the performance of the CCD imaging system. The developed system can handle astronomical image acquisition with additional functions of on-chip binning, sub-image acquisition using a SITe 1024×1024 1024×1024 CCD chip. Particularly the controller design of the system allows us great flexibility and versatility with the software system control and it is possible to cope with any format CCDs by any manufactures, in principle. The system performances are derived by mean variance test in our laboratory, which shows that the total system noise 10.5e-(R.M.S), Gain 1.9e-/ ADD, non-linearity 0.37% 0.37%
4,200원
10.
1998.12
구독 인증기관 무료, 개인회원 유료
Among the sample of red giant stars in the globular clusters M3 and M13 whose CN bands (3883\AA) have been measured by various authors, the stars on the red giant evolutionary state are selected to have their CN band distributions. It is found that all stars brighter than Mv = 0, are CN-strong in M3, while all stars except IV-29 are CN-strong in M13. It hints that the onset of meridional mixing is related with the RGB bumps of the clusters.
4,300원
11.
1998.12
구독 인증기관 무료, 개인회원 유료
The Blandford-Znajek process, which extracts the rotational energy of the supermassive black hole at the center of an active galactic nucleus, is now well explained and educated through the electronic circuit analysis established by Macdonald and Thorne. The Macdonald-Thorne circuits consist of the batteries and resistances of the central black hole and the astrophysical region around the accretion disk. In this letter we will consider the possibility whether we can connect coils and condensers in such circuits or not. If possible, that may explain a sudden corona-phenomenon in an active galactic nucleus. We conclude that a flash of order ~5×1040ergss−1 can occur around a \~109M⨀ \~109M⨀ black hole through this process.
4,000원
12.
1998.12
구독 인증기관 무료, 개인회원 유료
Observations of the J=1-0 transition line of HCN were made at the center of Comet C/1995 O1 (Hale-Bopp) from November, 1996 to April, 1997 with the 14-m radio telescope at the TRAO (Taeduk Radio Astronomical Observatory). From the obtained data, an HCN production rate at each observed date was derived. The rapid variation of the HCN production rate near the perihelion was detected, and it is thought to be caused by jet(s) from the nucleus. The correlation between the visual magnitude and the HCN production rate is found to be QHCN=27.03−0.11(mv−5logΔ) QHCN=27.03−0.11(mv−5logΔ) .
4,000원
13.
1998.12
구독 인증기관 무료, 개인회원 유료
We have simulated the interaction of supernova remnants with constant ambient medium to explore the dynamics of Type Ia supernova remnant. We assumed the supernova ejecta density distribution of the central constant and the outer power-law density distribution(ρ∝γ−n) (ρ∝γ−n) . We have calculated four different cases with different n. By scaling the length and time scales from the initial parameters-ejecta mass, ejecta energy, the ambient density, we could compare effects of the different density distribution of the ejecta on the dynamics of the SNRs. The radius of the outer forward shock converges the Sedov-Talyor solution at t' = 2.3 when the swept-up mass is 8 times of the ejecta mass. On the other hand, the motion of the reverse shock are largely affected by n. The ejecta with smaller n takes comparably long time to thermalize the whole ejecta at t′≃5.3,Msw≃18Mej t′≃5.3,Msw≃18Mej . We have applied our calculated results to obtain the ejecta density distributions of Tycho and SN1006 with n≃6 n≃6 .
4,500원
14.
1998.12
구독 인증기관 무료, 개인회원 유료
The structure and environments of the molecular clouds near the SNR HB3(G132.7±1.3) HB3(G132.7±1.3) are studied. The molecular complex which is located at the southern rim of HB3 was proposed by former investigators as the one interacting with HB3. This complex region of 2∘×2∘atl=133∘ 2∘×2∘atl=133∘ has been observed at 12CO,13CO,J=1−0ata1′ 12CO,13CO,J=1−0ata1′ , resolution with the 14-m radio telescope at Taeduk Radio Astronomy Observatory. We have reached to the following four conclusions. The possibility that these molecular complex and HB3 are interacting with each other cannot be supported with any of our data. The morphologies of the two show no similarities. Neither particular features for the interaction are found in the CO lines. The hypothetical 'Molecular wall' which was expected to exist on the northwestern rim of HB3 as a cause for the noncircular morphology of HB3 is turned out to be nonexistent in CO. The molecular complex which resembles a 'bar' at a low resolution is now resolved into a U-shaped shell. It seems that the U-shape is consist of two independent components. No peculiarities, such as unseen masses or bright stars capable of forming HlI regions, are found within the U-shape region. The total mass included in the complex is estimated to be Mtotal=2.9\~8.4×105M⨀ Mtotal=2.9\~8.4×105M⨀ , which is in good agreement with previous observations within errors. Considering about 12 clumps distinguishable within the complex, the total mass implies that masses of each of clumps are on the order of 104M⨀ 104M⨀ , which makes these good objects for further studies in relation to star-formation. Especially the clumps associated with W3 are worthy for more high resolution observations for better understanding of astrophysical phenomenon ongoing in them.
5,200원
15.
1998.12
구독 인증기관 무료, 개인회원 유료
We have carried out high precision orbit calculation, by using various numerical techniques with accuracy of higher than fourth order, in order for exact prediction on position and velocity of celestial bodies and artificial satellites. General second order ordinary differential equation has been solved numerically to test the performance for each of numerical methods. We have compared computed values with exact solution obtained by using universal variables for two body problem and discussed overall results of numerical methods used in our calculation. As a result, it is found that high order difference table method called as Gauss-Jackson method is best one with easiness and efficiency in the increase of accuracy by number of initial values.
4,600원
16.
1998.12
구독 인증기관 무료, 개인회원 유료
We have analyzed the sunspot and aurora data recorded in Go-Ryer-Sa. We have collected 35 records of sunspot observations for 46 days, and 232 records of auroral observations. To objectively estimate the periods of the solar activity appearing in these records a method of calculating the one-dimensional power spectrum from inhomogeneous data is developed, and applied to the sunspot and auroral data. We have found statistically significant 10.5 and 10 year periodicities in the distributions of sunspot and aurora records, respectively. These periods are consistent with the well-known solar activity cycle. There are indications of the long-term variations, but the period is not certain. We have also calculated the cross-correlations between the sunspot and auroral data. In particular, we have divided the aurora data into several subgroups to study their nature. We conclude that the historical records of strong auroral activity correspond to non-recurrent magnetic storms related to the sunspots. On the other hand, the records of weak auroral activity are thought to be related with the recurrent magnetic storms which occur frequently due to the coronal hole near the sunspot minimum.
6,700원
17.
1998.12
구독 인증기관 무료, 개인회원 유료
We have investigated future large telescopes, which should represent the next generation of Korean optical and infrared telescopes. We first studied the history of the development of large telescopes in the USA, European countries, and Japan. Based on these studies, we came up suitable Korean large telescopes, which fit the current status of Korea in terms of financial situation, required technology, sciences, and manpower. We presented the potential impacts of developing large telescopes on the relevant Korean industry and Korean astronomical society. We also discussed a possibility to install large Korean telescopes at foreign sites utilizing highly competitive seeings and twice available observing dates there.
4,800원
