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
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
Volume 9 (1994년 12월) 9건
1.
1994.12
구독 인증기관 무료, 개인회원 유료
We observed the 2 mm ortho and para transitions of H213CO H213CO toward the Orion Molecular Cloud-1 using the 12 m NRAO telescope at Kitt Peak. Total column densities of 3×1014 3×1014 and 2.8×1012cm−2 2.8×1012cm−2 have been derived at KL and the approximately 3 are minute north from the KL (3N) position, respectively. We discuss the abundances, ortho/para ratios and its chemical implications.
4,000원
2.
1994.12
구독 인증기관 무료, 개인회원 유료
We observed the molecular transitions of 12CO(1−0) 12CO(1−0) , 13CO(1−0) 13CO(1−0) , C18O(1−0) C18O(1−0) , CS(2-1), HCO+(1−0) HCO+(1−0) , and HCN(1-0) toward the high-latitude mole cular cloud MBM12. We derived total H2 H2 column densities for the two velocity components using the optically thin C18O C18O transition. Molecular abundances have been derived for the observed species at the core of this cloud, which appear to be less than an order of magnitude in fractional abundances relative to H2 H2 , compared to typical cold dark clouds.
4,300원
항성 제트의 원통형 혼합층 모델
3.
1994.12
구독 인증기관 무료, 개인회원 유료
We have developed a cylindrical mixing layer model of a stellar jet including cooling effect in order to understand an optical emission mechanism along collimated high velocity stellar jets associated with young stellar objects. The cylindrical results have been calculated to be the same as the 2D ones presented by Canto & Raga(1991) because the entrainment efficiency in our cylindrical model has been obtained to be the same value as the 2D model has given. We have discussed the morphological and physical characteristics of the mixing layers by the cooling effect. As the jet Mach number increases, the initial temperature of the mixing layer goes high because the kinetic energy of the jet partly converts to the thermal energy of the mixing layer. The initial cooling of the mixing layer is very severe, changing its outer boundary radius. A subsequent change becomes adiabatic. The number of the Mach disks in the stellar jet and the total radiative luminosity of the mixing layer, based on our cylindrical calculation, have quite agreed with the observations.
5,200원
4.
1994.12
구독 인증기관 무료, 개인회원 유료
We present two codes which estimates virial mass and LTE mass using IMFORT interface within IRAF (Image Reduction and Analysis Facility). It is discussed that threshold value (temperature or CO integrated intensity), which defines a reasonable cloud boundary and size, is the most important parameter determining accurate results. Several virial masses are to be obtained using the vir task, as well as three velocity dispersions including the centroid velocity dispersion, a turbulence indicator. LTE mass is to be estimated by using task lte as well as three by-product images. The 13CO 13CO abundance and threshold temperature of 13CO 13CO and 12CO 12CO peak temperatures are the most critical parameters in LTE technique.
4,900원
5.
1994.12
구독 인증기관 무료, 개인회원 유료
We have reviewed three different techniques to estimate molecular cloud mass, and discussed the uncertainties involved. We found that determination of the most important parameter, the 13CO 13CO abundance, is not very sensitive to the real LTE conditions, and that any possible error in deriving LTE column density may not introduce an error in the total gas column density, as far as the visual extinction is established for the object cloud. The virial technique always endows the largest mass estimate as there are several uncertainties, even if the cloud is in virial equilibrium. The strong indicator of the cloud perturbation is the centroid velocity dispersion. The mass using CO luminosity is based on the empirical law, but weakly dependent on the virial assumption, thus it still gives a larger mass estimate. The mass discrepancy is likely to be inevitable, and a factor of two or three difference between mass estimates could easily be attributed to the uncertainties mentioned above. The LTE mass estimate may be the most reliable one if we use the relation visual extinction and 13CO 13CO column density of the object cloud, and the intercept is included.
4,600원
6.
1994.12
구독 인증기관 무료, 개인회원 유료
The spectral types of stars can be classified by using Balmer discontinuity(DB DB ) and wavelength(λB λB ) expressed in terms of effective temperatures appeared in Balmer discontinuity. In this research, in order to classify stars, we used the well established observational data of high dispersion spectrophotometry for the spectral types and luminosity classes of stars in the Breger(1976) catalogue. Balmer discontinuity by effective temperatures of stars was accurately measured, and the λB λB was replaced to luminosity classes of MK system, because of the close relationship between the As and luminosity classes. We measured the energy gradients(ϕR ϕR ) of stars which were expressed as a function of spectral types in the interval of λλ4,000∼4600\AA λλ4,000∼4600\AA , and then obtained a new physical parameter(ϕ ϕ ) from the DB DB and ϕB ϕB . The new parameter, ϕ ϕ can be used instead of HD classifications of stars and can be used widely for spectrophotometrical classifications of stars.
4,900원
7.
1994.12
구독 인증기관 무료, 개인회원 유료
In Korea Astronomy Observatory, we developed a S/W package to compile the Korean Nautical Almanac. We describe the motivation to develop the S/W and explain the S/W package in general terms. In appendix, we describe the procedure to calculate the polaris table in more detail. When we developed the S/W, we paid much attention to produce accurate data. We also made great effort to automate the compilation of Nautical Almanac as far as possible, since the compilation is time consuming and labour extensive. As a result, the S/W we developed turns out to be very accurate and efficient to compile Nautical Almanac. In fact, we could compile a Korean Nautical Almanac in a few days.
4,900원
8.
1994.12
구독 인증기관 무료, 개인회원 유료
We have investigated intensively an optical telescope with 76cm diameter and CCD camera system in astronomical observatory of Kyung Hee university, in order to maximize instrumental functions of our observational equipments and to construct a more reliable photometric system. And computer softwares AUTO DOME, KH CCD and KH PHO for astronomical image observations and their automatic photometries with high accuracy have been made for observers w use our observational system conveniently and efficiently. Throughout careful examinations of these programs, it has been proved that the observing time by our program is shorter than that by manual operations, so that, fast and accurate observations can be executed with ease. For open cluster NGC 7063 observed with S/N value of 350 or more by KH PHO, we have found the magnitude measurements of 11 object stars would show 0.007 magnitude difference, comparing with magnitude data from IRAF/APPHOT. From automatic photometry of eclipsing binary, AB And observed by our software, total 220 data points with good quality have been acquired during 8 hours and so we could make a better light curve than that obtained from any observational results by domestic photoelectric photometry system.
4,000원
9.
1994.12
구독 인증기관 무료, 개인회원 유료
I have developed a UV and visible spectroscopic database (UVSD) for atoms and molecules, which are found in interstellar medium, stars, galaxies, and in the atmospheres of the earth, planets, satellites, and comets. This UV and visible database, which is machine-readable, consists of three different sub-databases depending upon the characteristics of the sub-databases: (A) atomic and molecular line listings from laboratory observations or theoretical studies; (B) absorption spectra measured in laboratories; and (C) solar UV, visible, and infrared spectral atlases. The UVSD is in a very initial stage of development compared with other well organized and established infrared and microwave databases. In order to make a good quality and complete database, substantial efforts should be made for the acquisition of scattered important data from laboratories or institutions, and then the acquired heterogeneous data should be peer-reviewed and standardized.
11,400원
