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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Astronomy and Space Sciences
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The Korean Space Science Society
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Volume & Issues
Volume 5, Issue 2 - Dec 1988
Volume 5, Issue 1 - Jun 1988
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Electron Beam Propagation in a Plasma
Min, Kyoung-W. ; Koh, Woo-Hee ;
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 1~8
Electron beam propagation in a fully ionized plasma has been studied using a one-dimensional particle simulation model. We compare the results of electrostatic simulations to those of electromagnetic simulations. The electrostatic results show the essential features of beam-plasma interactions. It is found that the return currents are enhanced by the beam-plasma instability which accelerates ambinet plasmas. The results also show the heating of ambient plasmas and the trapping of plasmas due to the locally generated electric field. The electromagnetic simulations show much the same results as the electrostatic simulations do. The level of the radiation generated by the same non-relativistic beam is slightly higher than the noise level. We discuss the results in context in context of the heating of coronal plasma during solar flares.
Ground-based and On-satellite Observations of Be and B Stars
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 9~18
Gamma Cassiopeae has been observe at Yonsei University Observatory(YUO) for 31 nights in the period 1983-1987 and a total of 312 UBV observations(104 in each colour) was secured. Light curves of
Cas in V, B-V, and U-B have been constructed with the YUO data; among them we present selected light curves of 5 different long nights. Discussed are the general photometric behaviour of
Cas, especially in connection with B-V changes, V/R variations of
, and high velocity narrow component(hvnc) exhibited in the far UV. Six spectral image sets of
Per archived on IUE satellite are reduced and their line profiles in C IV and Si IV resonance lines are analyzed to find out any change, but the evidence is unlikely.
Collision Orbite for Small Mass Ratio in the Restricted Three Body Problem
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 19~30
The existence of the j-type collision periodic orbit is examined on the condition of mass ratio 0.9878449 and Jacobian constant 2.9∼3.4. Using the Birckhoff's regularization method and the 5th order Runge-Kutta variable step-sized numerical roution introduced by Fehlberg (1968). we test their periodicities. As the results, 4 j-type collision orbits and 5 peculiar orbits are represented. There are good agreements in this collision orbits with the relationship between the period and the shape of orbit proposed by Pinotsis Zikides(1984).
Orbit Determination from Tracking Data of Artificial Satellite Using the Method of Differential Correction
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 31~43
The differential correction process determining osculating orbital elements as correct as possible at a given instant of time from tracking data of artificial satellite was accomplished. Preliminary orbital elements were used as an initial value of the differential correction procedure and iterated until the residual of real observation (O) and computed observation(C) was minimized. Tracking satellite was NOAA-9 or TIROS-N series. Two types of tracking data were prediction data precomputed from mean orbital elements of TBUS and real data obtained from tracking 1.70 GHz HRPT signal of NOAA-9 using 5 meter auto-track antenna in Radio Research Laboratory. Accrding to thacking data either Gause method or Herrick-Gibbs method was applied to preliminary orbit determination. In the differential correction stage we used both of the Escobal(1975)'s analytical method and numerical method using f, g series for the comparision. The results between analytical and numerical ones are nearly consistent. And the differentially corrected orbit converged to the same value in spite of the differences between preliminary orbits of each time span.
A Study on the Tracking and Position Predictions of Artificial Satellites(I) - A Study on the Methods of the Preliminary Orbit Determination-
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 45~51
Most of all methods of determining the preliminary orbit of an artificial Earth satellite are reviewed. The preliminary orbits of the methorological satellite NOAA-10 are determined using the studied methods and are compared with mean orbital elements determined at NASA. Through the comparision the preliminary orbital elements determined with Gauss type methods are more approximate to those of NASA than those calculated with Laplacian type ones. Our results indicate that Taff(1984)'s criticism on the Gauss method must be abandoned and Marsden (1985)'s analysis on the method is correct.
UBV Monitoring of Eps Aurigae (I)
Nha, Il-Seong ; Lee, Yong-Sam ; Kim, Ho-Il ; Lee, Kyoung-Hee ;
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 53~56
UBV photometric monitoring of Eps Aurigae has been made at Yonsei University Observatory since the 1982-1984 eclipse. Among observatios made in four seasons(1984-5, 1985-6, 1986-7, 1987-8) after the 1982-84 eclips ended the observations of the latest season are presented. Standardized UBV light curves of Eps Aur exhibit a light variation in a semi-regular fashion with the amplitudes of 0.12, 0.19, and 0.29 for V, B, and U, respectively. Duratiohs of this light variation may show a color dependency with the mean value of about 78 days whose minimum light on near JD2447118.
Photometric Study on the Spot-Double Star XY Ursae Majoris(I)
Lee, Woo-Baik ;
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 57~72
The long-term observational properties of the photometric behaviors of the short period(p=0.48 day) eclipsing binary system XY UMa are discussed. They are based on the UBV observatins, which were carried out by Geyer in the yaers 1955-1961, 1968, 1975-1984. Light curves of XY UMa revealed very large changes not only between consecutive observing nights, but also from season to season. Between 1955 and 1984, the mean system brightness increased about 30% during this time interfvals, meanwhile, the orbital period of this system was constant whithin 1.6% of its period. The colour index curve shows similar variations like the light curve but with a phase offset oscillation around the time instants of the primary minama. Observational evidence for photospheric and chromospheric activities on the XY Uma are also discussed.
UBV Light Curves of the Eclipsing Binary SW Lacertae
Journal of Astronomy and Space Sciences, volume 5, issue 1, 1988, Pages 73~79
New differential photoelectric observations in UBV system of the W UMa-type eclipsing binary SW Lac presented. The data were obtained on 4 nights from October in 1987 using the 61cm reflector at Sobaeksan Astronomical Observatory. These light curves are compared with recent published light curves in order to check the light curve variations and magnitude difference of minimum light phases. Four times of minimum light are deduced and the orbital period variation of SW Lac has been discussed.