모달창 닫기
- 홈으로 이동
1968년 ~ 2025년까지 1,227 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 : 1,227건 (DB Construction : 1,227 Articles)
총 게시글 1,227건
페이지 101/123
1001
- IWASAKI KYOSUKE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.357-358
- 1996
- 원문 바로보기
Reanalysis of the observations of Mars made at the Hida Observatory in 1975 with a new image processing method is reported. Red filter images taken in the period before vernal equinox (areocentric longitude of the sun Ls=<TEX>$0^{\circ}$</TEX>) revealed dark surface features at the northern high latitudes, while blue filter images taken at the same time showed the extensive polar hood. The latitude of the northernmost feature observed was about <TEX>$67^{\circ}$</TEX>N. An extensive north polar cap, which is predicted by most of the existing models and observed with Viking, did not exist in our reanalyzed images obtained at the Hida Observatory in 1975.
1002
- LEE SANG-GAK
- Journal of the Korean astronomical society = 천문학회지
- 29, n.2
- pp.157-170
- 1996
- 원문 바로보기
In order to determine the metallicity of a globuar cluster, M3,by using the spectral indices, a kind of index grid has been establshed by stars in globular clusters, M3, M15, M71 and old open cluster, NGC 188. The indices were measured from the medium resolution spectra of about <TEX>$2{\AA}$</TEX>. The summed indices were used to determine metallicity in order to increase signals. It is found that the core depth index is measured more accurately and leads result more accurate than the pseudo-equivalent width index. This method can be further improved by including many more calibration globular clusters of various metallicity to make finer grids. By this method, the metallicity of M3 is determined as <TEX>$[Fe/H] = -1.46\pm0.15$</TEX>.
1003
- LEE MYUNG GYOON
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.67-68
- 1996
- 원문 바로보기
1004
- MAKOTO INOUE
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.419-420
- 1996
- 원문 바로보기
The VLBI Space Observatory Program (VSOP) is a worldwide project of one radio telescope in space with many ground radio telescopes. The concerted space VLBI network enables us to reveal high resolution and high quality images of radio sources. The space radio telescope is anticipated to be launched in January/February 1997, and collaborative observations have been coordinated. The basic parameters of the system and present status are given.
1005
- AGRAWAL P. C.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.429-432
- 1996
- 원문 바로보기
An x-ray astronomy experiment consisting of three collimated proportional counters and an X-ray Sky Monitor (XSM) was flown aboard the Indian Satellite IRS-P3 launched on March 21, 1996 from SHAR range in India. The Satellite is in a circular orbit of 830 km altitude with an orbital inclination of <TEX>$98^{\circ}$</TEX> and has three axis stabilized pointing capability. Each pointed-mode Proportional Counter (PPC) is a multilayer, multianode unit filled with P-10 gas (<TEX>$90\%$</TEX> Ar + <TEX>$10\%\;CH_4$</TEX>) at 800 torr and having an aluminized mylar window of 25 micron thickness. The three PPCs are identical and have a field of view of <TEX>$2^{\circ}{\times}2^{\circ}$</TEX> defined by silver coated aluminium honeycomb collimators. The total effective area of the three PPCs is about 1200 <TEX>$cm^2$</TEX>. The PPCs are sensitive in 2-20 keV band. The XSM consists of a pin-hole of 1 <TEX>$cm^2$</TEX> area placed 16 cm above the anode plane of a 32 cm<TEX>$\times$</TEX>32 cm position sensitive proportional counter sensitive in 3-8 keV interval. The position of the x-ray events is determined by charge division technique using nichrome wires as anodes. The principal objective of this experiment is to carry out timing studies of x-ray pulsars, x-ray binaries and other rapidly varying x-ray sources. The XSM will be used to detect transient x-ray sources and monitor intensity of bright x-ray binaries. Observations of black-hole binary Cyg X-1 and few other binary sources were carried out in early May and July-August 1996 period. Details of the x-ray detector characteristics are presented and preliminary results from the observations are discussed.
1006
- JEONG K. S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.181-182
- 1996
- 원문 바로보기
1007
- HIDAYAT BAMBANG
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.455-457
- 1996
- 원문 바로보기
1008
- LEE SEE WOO
- Journal of the Korean astronomical society = 천문학회지
- 28, n.1
- pp.45-59
- 1995
- 원문 바로보기
In the best observed Pleiades cluster, the luminosity function(LF) and mass function(MF) for main sequence(MS) stars extended to <TEX>$Mv{\approx}15.5(V{\approx}21)$</TEX> are very similar to the initial luminosity function(ILF) and initial mass function(IMF) for field stars in the solar neighborhood showing a bump at log <TEX>$m{\simeq}-0.05$</TEX> and a dip at log <TEX>$m{\simeq}-0.12$</TEX>. This dip is equivalent to the Wielen dip appearing in the LF for the field stars. The occurence of these bump and dip is independent of adopted mass-luminosity relation(MLR) . and their characteristics could be explained by a time-dependent bimodal IMF. The model with this IMF gives a total cluster mass of <TEX>$\~700M_\bigodot,\;\~25$</TEX> brown dwarfs and <TEX>$\~3$</TEX> white dwarfs if the upper mass limit of progenitor of white dwarf is greater than <TEX>$4.5M_\bigodot$</TEX>. The cluster age on the basis of LF for brightest stars is given by <TEX>$\~8\times10^7yr$</TEX> and all stars in the cluster lie along the single age sequence in the C-M diagram without showing a large dispersion from the sequence.
1009
- Park, Yong-Sun
- Journal of the Korean astronomical society = 천문학회지
- 28, n.2
- pp.255-264
- 1995
- 원문 바로보기
The HII region S140 and the associated molecular cloud L1204 have been observed with 10 molecular transitions, CO (1-0), <TEX>$^{13}CO$</TEX> (1-0), <TEX>$C^{18}O$</TEX> (1-0), CS (2-1), <TEX>$HCO^+$</TEX> (1-0), HCN (1-0), SO (<TEX>${2_2}-{1_1}$</TEX>), <TEX>$SO_2(2_{20}-3_{13})$</TEX>, OCS (8-7), and <TEX>$HNCO\;(4_{04}-3_{03})$</TEX> with <TEX>${\sim}50'$</TEX> angular resolutions. More than 7,000 spectra were obtained in total. The morphology of this region shows a massive fragment (the S140 core) and the extended envelope to the northeast. Several gas condensations have been identified in the envelope, having masses of <TEX>${\sim}10^{3}M_{\odot}$</TEX> and gas number densities of <TEX>${\lesssim}10^{4}cm^{-3}$</TEX> to <TEX>$3{\times}10^{5}cm^{-3}$</TEX> in their cores. The column densities of the observed molecular species toward the S140 core appear to be the typical warm clouds' abundances. It seems to be that the S140 core and L1204 have been swept up by an expanding shell called the Cepheus bubble. The large value of <TEX>$L_{IR}$</TEX>(embedded\;stars)/<TEX>$M_{cloud}\;{\sim}\;5\;L_{\odot}$</TEX>/<TEX>$M_{\odot}$</TEX> of the S140 core may suggest that the star formation has been stimulated by the HII region, but the shock velocity and the pressure of the region seem to give a hint of the spontaneous star formation by the self gravity.
1010
- LEE MYUNG GYOON
- Journal of the Korean astronomical society = 천문학회지
- 28, n.1
- pp.31-43
- 1995
- 원문 바로보기
We present UBVRI CCD photometry of the Type Ie supernova SN 19941 in M51 which was discovered on April 2, 1994 (UT). UBVRI CCD photometry of SN 1994 I were obtained for the period of the first two months from April 4, 1994, using the Seoul National University Observatory 60 cm telescope. The light curves of SN 19941 show several interesting features: (a) SN 19941 reaches the maximum brightness at B-band on April 8.23 (B = 13.68 mag), at V-band on April 9.10 (V = 12.89 mag), and at I-band on April 10.32 (I = 12.48 mag); (b) The light curves around the maximum brightness are much narrower than those of other types of supernovae; (c) The light curves after the peak decline more steeply than those of other types of supernovae; and (d) The colors get redder from <TEX>$(V-R){\approx}0.2 mag ((V - I){\approx} 0.3 mag, (B - V){\approx}0.7 mag)$</TEX> on April 4 to <TEX>$(V-R){\approx}0.6 mag ((V-1){\approx}0.9 mag, (B-V){\approx}1.3 mag)$</TEX> on April 18. Afterwards (V - R) colors get bluer slightly <TEX>$(by\~0.005 mag/day)$</TEX>, while (V-I) colors stay almost constant around <TEX>$(V-1){\approx}1.0 mag$</TEX>. The color at the maximum brightness is (B-V)=0.9 mag, which is <TEX>$\~1$</TEX>mag redder than the mean color of typical Type la supernovae at the maximum brightness. The light curves of SN 1994I are similar to those of the Type Ie supernova SN 1962L in NGC 1073. Adopting the distance modulus of <TEX>$(m-M)_0 = 29.2 mag$</TEX> and the reddening of E(B - V) = 0.45 mag [Iwamoto et al. 1994, preprint for ApJ], we derive absolute magnitudes at the maximum brightness of SN 1994I, Mv(max) = -17.7 mag and MB(max) = -17.4 mag. This result shows that SN 1994I was <TEX>$\~2$</TEX>mag fainter at the maximum brightness compared with typical Type Ia supernovae. A narrower peak and faster decline after the maximum in the light curve of SN 1994I compared with other types of supernovae indicate that the progenitor of SN 1994I might be a lower mass star compared with those of other types of supernovae.