Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of The Korean Astronomical Society
Journal Basic Information
Journal DOI :
The Korean Astronomical Society
Editor in Chief :
Volume & Issues
Volume 8, Issue 1 - Dec 1975
Selecting the target year
A Model of the Mass Distribution of the Galaxy-II
Yu, Kyung-Loh ; Kim, Sung-Kyun ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 1~2
An improved version of the galatic mass distribution has been derived by increasing the number of shells in each spheroid of our earlier model. It is found that the increase of the number of the shell improves the model considerably, thus making it agree far better with observations.
A Model of the Mass Distribution of the Galaxy-III
Yu, Kyung-Loh ; Kang, Yong-Hee ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 3~9
Densities of the three constituent spheroids of the same eccentricity as our earlier model of the Galaxy are assumed to be given by an analytical form of
are obtained by comparing with the results of the previous model. Using three values of
(r) the galactic rotation curve, mass of each spheroid and the whole Galaxy are calculated, and the three dimensional density distribution in the Galaxy is also obtained. The calculated rotation curve of the model Galaxy is in good agreement with the observed curve, and the shape of the cross section of the model Galaxy given by the computed density is very similar to the inferred shape of the spiral galaxies.
The Effective Temperature of the N Stars
Lee, Young-Bom ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 11~14
Photoelectric observations were made of four N stars (HD 51208, HD 75021, V 1942 Sgr, and RU Vir) at careful1y chosen discrete wavelengths between
bandpass width. Their effective temperatures have been derived by fitting the black-body radiation curve to the observed continuum intensities at
. The resulting temperature ranges from
. It is probable that almost all the N stars belong to this range of temperature. However, the temperatures of very red N stars can not be well determined due to large variability and redistribution of their radiation energy arising from the graphite shells around them.
Photographic Observation and Reduction Technique by a Multiple-exposure Procedure
Jeong, Jang-Hae ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 15~23
A new technique of photographic observations is developed for the determination of time of minimum light of eclipsing binary. An instrumental system to accomplish the observation is described. With this instrument the atmospheric extinction coefficients in Seoul are observed, and four times of minimum light for Algol and W UMa are determined.
Photographic Time of Minimum Light for VV Orionis
Lee, Woo-Baik ; Nha, Il-Seong ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 25~27
A time of minimum light for VV Orionis has been determined photographically using techniques developed by Jeong. The observed time of minimum light shows that VV Ori exhibits a constant orbital period. The O-C computed with the light elements given by Eaton is found to be
, 0070. An attempt to correct for night-to-night shifts for plates taken on three nights in February and March 1975, was unsuccessful and thus the complete light curve initially planned was not obtained.
Effect of a Magnetic Field on Electrical Conductivity of a Partially Ionized Plasma
Yun, Hong-Sik ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 29~34
Solar electrical conductivity has been calculated, making use of Yun and Wyller's formulation. The computed results arc presented in a tabulated form as functions of temperature and pressure for given magnetic field strengths. The results of the calculation show that the magnetic field does not play any important role in characterizing the electrical conductivity of the ionized gas when the gas pressure is relatively high (e.g.,
). However, when the gas pressure is low (e.g.,
), the magnetic field becomes very effective even if its field strength is quite small (e.g.,
gauss). It is also found that, except for lower temperature region (e.g.,
), there is a certain linear relationship in a log- log graph between the pressure and the critical magnetic field strength, which is defined as a field strength capable of reducing the non-magnetic component of the electrical conductivity by 20%.
On the Stellar Convective Zone and the Stellar Evolution
Hyun, Jong-June ;
Journal of The Korean Astronomical Society, volume 8, issue 1, 1975, Pages 35~39
Effect of the ratio of mixing length to the pressure scale-height
=l/HP on the effective temperature has been investigated under some simplifying assumptions. The result is compared with that of the existing model calculations. The role of convection zone in the stellar evolution is briefly summarized.