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1968년 ~ 2024년까지 1,211 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 : 1,211건 (DB Construction : 1,211 Articles)
총 게시글 1,211건
페이지 96/122
951
- ANDERSEN J.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.127-128
- 1996
- 원문 바로보기
The solar neighbourhood is the starting point for studies of the structure and evolution of the Galactic disk. Yet, our knowledge of the relative frequencies, distances, ages, chemical abundances, velocities, and birthplaces of the nearby stars is severely incomplete. We have determined complete, homogeneous, and precise such data for a kinematically unbiased sample of <TEX>$\~$</TEX>12,000 local F and G dwarf stars and describe a first, significant result from it.
952
- 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.
953
- TOBIN WILLIAM
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.89-91
- 1996
- 원문 바로보기
Within the next few years eclipsing binaries should yield primary distance measurements for the Magellanic Clouds as well as provide tests of theoretical low-metallicity stellar models.
954
- 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.
955
- STALIN C. S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.343-344
- 1996
- 원문 바로보기
Solar IR spectra have been utilised by us to derive log gf values for atomic lines due to 17 chemical elements. in the J and H bands, i.e. in the wavelength ranges 1.00 - 1.34 <TEX>${\mu}m$</TEX> and 1.49 - 1.80 <TEX>${\mu}m$</TEX> respectively. The observed central line depths were based on the FTS atlases published at. Liege and KPNO. We also reprot new log gf values for 51 lines for which neither theoretical nor experimental values are available till date.
956
- STEINITZ RAPHAEL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.237-238
- 1996
- 원문 바로보기
957
- VISHNIAC ETHAN T.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.201-204
- 1996
- 원문 바로보기
Magnetic fields are thought to playa role in a wide variety of important astrophysical processes, from angular momentum transport and jet formation in accretion disks to corona formation in stars. Unfortunately, the dynamics of magnetic fields in astrophysical plasmas are extremely complicated, and the success of current theoretical models and computer simulations seems to be inversely correlated with the amount of observational detail available to us. Here I will discuss some of the more striking conflicts between numerical simulations and observations, and present an explanation for them based on an important dynamical process which is not adequately modeled in current numerical simulations. These processes will lead to the formation of flux tubes in stars and accretion disks, in accordance with observations. I will discuss some of the implications of flux tube formation for stellar and accretion disk dynamos.
958
- 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.
959
- VERMA V. K.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.391-392
- 1996
- 원문 바로보기
We have developed and tested a CCD camera (100 <TEX>$\times$</TEX> 100 pixels) system for observing Ha images of the solar flares with time resolution> 25 msec. The 512 <TEX>$\times$</TEX> 512 pixels image of CCD camera at 2 Mpixels/sec can be recorded at the rate of more than 5 frame/sec while 100 <TEX>$\times$</TEX> 100 pixels area image can be obtained 40 frames/sec. The 100 <TEX>$\times$</TEX> 100 pixels image of CCD camera corresponds to 130 <TEX>$\times$</TEX> 130 arc - <TEX>$sec^2$</TEX> of the solar disk.
960
- 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.