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1968년 ~ 2023년까지 1,187 건의 한국천문학회지를 격월간 확인하실 수 있습니다.
- The Korean Astronomical Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-4614 (ISSN : 1225-4614)
1225-4614
- DB구축현황 : 1,187건 (DB Construction : 1,187 Articles)
총 게시글 1,187건
페이지 96/119
951
- AGRAWAL P. C.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.219-221
- 1996
- 원문 바로보기
The x-ray pulsar GX 1+4 was observed by us in four balloon- borne experiments carried out from Hyderabad, India during 1991-1995 period with a hard x-ray telescope. The x-ray telescope consists of two collimated large area xenon-filled proportional counters with an effective area of <TEX>$2400 cm^2$</TEX>, a field of view of <TEX>$5^{\circ}{\times}5^{\circ}$</TEX> and sensitive in the energy band of 20 - 100 keV. The pulsar was detected in bright state in two of the four experiments and x-ray pulsations with 120 second period were detected clearly. Pulsation period, rate of change of period with time, pulse fraction, pulse profile and energy spectra of the source were determined from these studies. During March 1995 observation, the x-ray pulse of GX 1+4 was found to be double-peaked compared to a single-peak pulse profile detected in December 1993. Details of these results are presented and their interpretation discussed in terms of the current accretion models of x-ray binaries.
952
- KANG IVIIN-YOUNG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.263-264
- 1996
- 원문 바로보기
We have solved the radiative transfer problem using a Sobolev approximation with an escape probability method in case of the supersonic expansion of a stellar envelope to an ambient medium. The radiation from the expanding envelope turns out to produce a P-Cygni type profile. In order to investigate the morphology of the theoretical P-Cygni type profile, we have treated <TEX>$V{\infty},\;V_{sto},\;{\beta}$</TEX> (parameter for the velocity field), M and <TEX>$\epsilon$</TEX> (parameter for collisional effect) as model parametrs. We have found that the velocity field and the mass loss rate affect the shapes of the P-Cygni type profiles most effectively. The secondarily important factors are <TEX>$V{\infty},\;V_{sto}$</TEX>. The collisional effect tends to make the total flux increase but not so .much in magnitude. We have infered some physical parameters of 68 Cyg, HD24912, and <TEX>$\xi$</TEX> persei such as V<TEX>$\infty$</TEX>, M from the model calculation, which shows a good agreement with the observational results.
953
- LEE C. W.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.161-163
- 1996
- 원문 바로보기
We have studied the response of molecular clouds in the Galactic disk to a rotating bar by conducting Smoothed Particle Hydrodynamics (SPH) simulations for the Galaxy in order to understand the dynamical structures of the Galactic Center (GC) molecular clouds, and their implications. In our study it was found that the structures of GC molecular clouds could be induced by the combined effects of rotating bar potential, the hydrodynamic collisions and gravitational miss collisions between the clouds.
954
- AI GUOXIANG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.415-418
- 1996
- 원문 바로보기
Space Solar Telescope (SST) is a space project for solar research, its main parameters are that total weight 2.0T, sun synchronous polar circular orbit, altitude of the orbit 730KM, 3 axis stabilized attitude system, power 1200W, telemetry of the downlink rate 30Mb/s, size <TEX>$5{\ast}2{\ast}2\;M^3$</TEX>, mission life 3 years. It is expected it will be launched in 2001 or later. The main objective is structure and evolution of solar vector magnetic field with very high spatial resolution. The payloads are consisted of 6 instruments: Main optical telescope with 1-M diameter and diffraction limited resolution 0.1 arc second, EUV imaging telescope with a bundle of four telescopes and 0.5 arc second resolution, spectrometric optical coronagraph, wide band spectrometer, H-alpha and white light telescope and solar and interplanetary radiospectrometer. An assessment study between China and Germany is under operation.
955
- KIM SANG-JOON
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.347-350
- 1996
- 원문 바로보기
Spectroscopic data between 7 and 15 microns obtained in 1979 by Voyager 1 and 2 Infrared Interferometer Spectrometer (IRIS) have been revisited. Using the spectral data, Jupit.er images have been constructed at the emission bands of hydrocarbons, such as methane, ethane, and acetylene. The resultant. images show differences in emission intensities in the polar regions, suggesting inhomogeneous distributions of the hydrocarbons over the auroral regions of Jupiter.
956
- DEHGHANI M. H.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.285-286
- 1996
- 원문 바로보기
A systematric method of exploring the 'geometrical' and 'non-geometrical' constants of the motion for an arbitrary spacetime is presented. This is done by introducing a series of coupled differential equation for the generators of the symmetry group of Vlasov's equation. The method is applied to the case of the maximaly symmetric spectime, and the geometrical and non-geometrical constants of motion are obtained.
957
- YAMAOKA HITOSHI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.213-214
- 1996
- 원문 바로보기
We are promoting a supernova(SN) search project with medium size (60cm-105cm) telescopes belonging to public observatories in Japan. The main purpose is to measure the SNe Ia rate, which plays an important role in the chemical and dynamical evolution of galaxies. We expect to measure the SN rate in E/SO galaxies within the <TEX>$35\%$</TEX> error after 2 years run, and the longer run will give the smaller error.
958
- KIM SEUNG-LEE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.1
- pp.43-51
- 1996
- 원문 바로보기
We present test results of time-series CCD photometry to investigate the photometric precision of the BOAO (Bohyunsan Optical Astronomy Observatory) 1.8m telescope. A well-known field of the old open cluster M67, which includes two pulsating blue stragglers and two W UMa type binaries, was monitored for 3.5 hours on February 22, 1996. We have collected 148 V frames and 3 B frames. Photometric noises which consist mainly of photon noise and scintillation noise, were lowered down to about 1.9 mmag for stars of <TEX>$10.\;^m5$</TEX> in M67 with exposure time of 20 seconds. From the C-M diagram for M67, a number of observational properties were derived; E(B-V) = 0.03, (V-Mv)o = 9.6, Age = 4 Gyr. We obtained light curves for four known variable stars and confirmed their variational characteristics. The pulsating blue stragglers show a low amplitude (about 0.01 mag) of light variation.
959
- MCGREGOR PETER J.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.119-122
- 1996
- 원문 바로보기
The case for a massive black hole in the center of the Galaxy is reassessed using improved modeling techniques and observational data. A dark mass of <TEX>${\~}{\times} 10^6$</TEX> Mo is present within 0.2 pc of the Galactic center. However, the available data can be modeled, without appealing to a massive black hole, using an extended distribution of dark stellar remnants (neutron stars and stellar mass black holes) provided that the stellar initial mass function in the central parsec is deficient in stars less massive than <TEX>$\~$</TEX>1 Mo. Such a situation may be a natural consequence of repeated gas build-up followed by starbursts in the central region. A clear distinction between this and the massive central black hole model cannot be made using red giant tracers outside 0.2 pc due to uncertainties in the radial velocity dispersion distribution. The cluster of massive early-type emission-line stars in the central parcsec more effectively probe the mass distribution close to Sgr A <TEX>$\ast$</TEX>, but their small number and partial rotational support complicate mass determinations. Proper motion determinations for stars within 0.5' of Sgr A<TEX>$\ast$</TEX> may be the most effective means of unambiguously determining the mass distribution in the immediate vicinity of the Galactic center.
960
- POGODIN MIKHAIL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.259-259
- 1996
- 원문 바로보기
Circumstellar peculiarities of the young Herbig Ae/Be stars are analyzed using high-resolution CCD spectroscopic data, obtained in 1991-1996 at the ESO and the Crimean Astrophysical Observatory (about 450 spectrograms). The results of investigation of the rapid line variability in H<TEX>$\alpha$</TEX>, H<TEX>$\beta$</TEX>, HeI 5876 and DNaI lines are presented for AB Am, HD 163296, HD 36112, HD 100546, and HD 50138. We conclude that the behaviour of these lines can be explained in the framework of the model containing an equatorially concentrated and azimuthally inhomogeneous stellar wind, and an external cool shell that occasionally looses matter in form of infall onto the star.