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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 52/122
511
- ELKHATEEB M. M.
- Journal of the Korean astronomical society = 천문학회지
- 38, n.1
- pp.13-16
- 2005
- 원문 바로보기
We present a period analysis of the well known <TEX>$\beta$</TEX> Lyrae type eclipsing binary GO Cyg <TEX>$(P= 0^d .7177)$</TEX>. Several new times of minimum light, recorded photoelectrically, have been gathered. Analysis of all available eclipse timings of GO Cyg has confirmed a significant period increase with rate of <TEX>$2.52 {\times} 10^{-10}$</TEX> day / cycle, also new period has been estimated. New linear and quadratic ephemerides have been calculated for the system.
512
- KOKUBO EUCHIRO
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.153-155
- 2005
- 원문 바로보기
We have developed the four-dimensional digital universe theater at which we can visualize the observational data and theoretical models of astronomical objects stereoscopically. The astronomical objects cover all scales of the universe from the solar system to the large-scale structure of the universe. We have also produced the three-dimensional movies of various astronomical processes based on the results of computer simulations. We plan to distribute all the products of this project through the internet.
513
- KO JONGWAN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.149-151
- 2005
- 원문 바로보기
We have studied the environmental effect on optical-NIR color gradients of 273 nearby elliptical galaxies. Color gradient is a good tool to study the evolutionary history of elliptical galaxies, since the steepness of the color gradient reflects merging history of early types. When an elliptical galaxy goes through many merging events, the color gradient can be get less steep or reversed due to mixing of stars. One simple way to measure color gradient is to compare half-light radii in different bands. We have compared the optical and near infrared half-light radii of 273 early-type galaxies from Pahre (1999). Not surprisingly, we find that <TEX>$r_e(V)s$</TEX> (half-light radii measured in V-band) are in general larger than <TEX>$r_e(K)s$</TEX> (half-light radii measured in K-band). However, when divided into different environments, we find that elliptical galaxies in the denser environment have gentler color gradients than those in the less dense environment. Our finding suggests that elliptical galaxies in the dense environment have undergone many merging events and the mixing of stars through the merging have created the gentle color gradients.
514
- MULLER SEBASTIEN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.245-248
- 2005
- 원문 바로보기
We present mm observations with the IRAM 30m radiotelescope of the HCN (J=1-0) and HCO+ (J=1-0) emission lines from Giant Moleculat Clouds (GMC) in the disk of the Andromeda Galaxy, The selected GMC targets have various morphology and environments, including locations within spiral arms or in interarm regions and with galactocentric radii ranging from 2.4 to 15.5 kpc over the disk. The radial distributions of the ratios HCN/CO and HCO+ /CO are discussed and their values are compared to other galaxies.
515
- TANIGUCHI YOSHIAKI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.187-190
- 2005
- 원문 바로보기
The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST) treasury project. The COSMOS aims to perform a 2 square degree imaging survey of an equatorial field in I(F814W) band, using the Advanced Camera for Surveys (ACS). Such a wide field survey, combined with ground-based photometric and spectroscopic data, is essential to understand the interplay between large scale structure, evolution and formation of galaxies and dark matter. In 2004, we have obtained high-quality, broad band images of the COSMOS field (B, V, r', i', and z') using Suprime-Cam on the Subaru Telescope, and we have started our new optical multi-band program, COSMOS-21 in 2005. Here, we present a brief summary of the current status of the COSMOS project together with contributions from the Subaru Telescope. Our future Subaru program, COSMOS-21, is also discussed briefly.
516
- IZUMIURA HIDEYUKI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.81-84
- 2005
- 원문 바로보기
We are undertaking an extra-solar planet search around G-type giant stars by means of Doppler technique using an iodine absorption cell installed to the high dispersion echelle spectrograph for the 188 cm reflector at Okayama Astrophysical Observatory (Okayama Planet Search Program, OPSP). Having detected the first planet candidate (Sato et al. 2003)the search has been proved very promising. Taking advantage of this success, we are trying to develop OPSP to an international collaborative work. We here report the current status of our efforts for establishing such collaborations, namely, those with Chinese and Korean astronomers. We also propose to establish an East-Asian network to search for extra-solar planets around G-type giant stars with the transit detecting technique as well as the Doppler technique, asking other persons/groups to join us to enjoy the planet search.
517
- CHEN YANG
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.211-214
- 2005
- 원문 바로보기
We performed a spatially resolved spectroscopic study of the thermal composite supernova remnant 3C 391 by the Chandra observation. Broad- and narrow-band X-ray images show a southeast-northwest elongated morphology and unveil a highly clumpy structure of the remnant. The spectral analysis for. the small-scale features indicates normal metal abundance and uniform temperature for the interior gas. The properties of the hot gas are largely in agreement with the cloudlet evaporation model as a main mechanism for the 'thermal composite' X-ray appearance, though radiative rim and thermal conduction may also be effective. An unresolved X-ray source, with a power-law spectrum, is observed on the northwest border. The equivalent width images reveal a faint finger-like protrusion in Si and S lines out of the southwest radio border.
518
- KAIFU NORIO
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.325-328
- 2005
- 원문 바로보기
I report here about the future direction of cooperation of astronomy in East Asia region, which has been a long-years subject of the EAMA since 1990. During this EAMA-6 we had many positive discussions and remarkable progress toward the promotion of our cooperation. We also had an 'East Asian Observatory' WG meeting yesterday with many attendants, and actively discussed this important subject in some detail. The following report is to summarize the fruitful products we had in the EAMA-6 discussions and in past EAMA activities, and to propose a direction and some action items toward the bright future of astronomy in East Asia.
519
- LYO A-RAN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.241-244
- 2005
- 원문 바로보기
We have analysed near-infrared JHKL observations of the members of the <TEX>$\approx$</TEX>9 Myr-old <TEX>$\eta$</TEX> Chamaeleontis cluster. Using (J - H)/(K - L) and (H - K)/(K - L) IR colour-colour diagrams for the brightest 15 members of the cluster, we find the fraction of stellar systems with near-IR excess emission was 0.60 <TEX>$\pm$</TEX> 0.13 (2<TEX>$\sigma$</TEX>). For the CTT and WTT star population, we also find a strong correlation between the IR excess and Ha emission which is also known as an accretion indicator. The (K - L) excess of these stars appears to indicate a wide range of star-disk activity; from a CTT star with high levels of accretion, to CTT - WTT transitional objects with evidence for some on-going accretion, and WTT stars with weak or absent IR excesses. Among the brightest 15 members, four stars (RECX 5, 9, 11 and ECHA J0843.3-7905) with IR excesses <TEX>${\Delta}$</TEX>(K - L) > 0.4 mag and strong or variable optical emission were identified as likely experiencing on-going mass accretion from their circumstellar disks which we confirmed their accretion disks from the optical high-resolution echelle spectroscopic study. The result-ing accretion fraction of 0.27 <TEX>$\pm$</TEX> 0.13 (2<TEX>$\sigma$</TEX>) suggests that the accretion phase, in addition to the disks themselves, can endure for at least <TEX>${\~}$</TEX>10 Myr.
520
- Seo, Haing-Ja
- Journal of the Korean astronomical society = 천문학회지
- 38, n.4
- pp.471-478
- 2005
- 원문 바로보기
Spectroscopic data obtained by the Infrared Interferometer Spectrometer (IRIS) aboard Voyager 1 and 2 have been re-visited. Using the spectroscopic data and footprints of the IRIS aperture on the planet, we constructed images of the stratosphere of Jupiter at the emission bands of hydrocarbons including <TEX>$CH_4,\;C_2H_6,\;C_2H_2,\;C_3H_4,\;C_6H_6$</TEX>, and <TEX>$C_2H_4$</TEX>. Thermal emission from the hydrocarbons on Jupiter originates from a broad region of the stratosphere extending from 1 to 10 millibars. We averaged the data using a bin of 20 degrees of longitude and latitudes in order to increase signal-to-noise ratios. The resultant images show interesting wave structure in Jupiter's stratosphere. Fourier transform analyses of these images yield wavenumbers 5 - 7 at mid-Northern and mid-Southern latitudes, and these results are different from those resulted from previous ground-based observations and recent Cassini CIRS, suggesting temporal variations on the stratospheric infrared pattern. The comparisons of the Voyager 1 and 2 spectra also show evidence of temporal intensity variations not only on the infrared hydrocarbon polar brightenings of hydrocarbon emissions but also on the stratospheric infrared structure in the temperate regions of Jupiter over the 4 month period between the two Voyager encounters. Short running title: Stratospheric Images of Jupiter derived from Voyager IRIS Spectra.