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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 48/122
471
- OHASHI NAGAYOSHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.103-106
- 2005
- 원문 바로보기
The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy & Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m radio telescopes comprise the array with currently working receiver bands at 230, 345, and 690 GHz. The array will have 8 receiver bands covering the frequency range of 180-900 GHz. The backend is flexible analog-digital correlator with a full bandwidth of 2GHz, which is very powerful to cover several line emissions simultaneously. The current status and future plans of the SMA are described with emphasis on Taiwanese efforts.
472
CURRENT STATUS OF THE INSTRUMENTS, INSTRUMENTATION AND OPEN USE OF OKAYAMA ASTROPHYSICAL OBSERVATORY
- YOSHIDA MICHITOSHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.117-120
- 2005
- 원문 바로보기
Current instrumentation activities and the open user status of Okayama Astrophysical Observatory (OAO) are reviewed. There are two telescopes in operation and one telescope under reforming at OAO. The 188cm telescope is provided for open use for more than 200 nights in a year. The typical over-subscription rate of observation proposals for the 188cm telescope is <TEX>${\~}$</TEX> 1.5 - 2. The 50cm telescope is dedicated to <TEX>$\gamma$</TEX>-ray burst optical follow-up observation and is operated in collaboration with Tokyo Institute of Technology. The 91cm telescope will become a new very wide field near-infrared camera in two years. The high-dispersion echelle spectrograph (HIDES) is the current primary instrument for the open use of the 188cm telescope. Two new instruments, an infrared multi-purpose camera (ISLE) and an optical low-dispersion spectrograph (KOOLS), are now under development. They will be open as common use instruments in 2006.
473
- KIM TAEHYUN
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.145-148
- 2005
- 원문 바로보기
We present a photometric study of galaxies in the central regions of six nearby galaxy clusters at redshift z=0.0231<TEX>${\~}$</TEX>0.0951. We have derived BVI photometry of the galaxies from the CCD images obtained at the Bohyunsan Optical Astronomical Observatory (BOAO) in Korea, and JHKs photometry of the bright galaxies from the 2MASS extended source catalog. Comparing the galaxy photometry results with the simple stellar population model of Bruzual & Charlot (2003) in the optical & NIR color-color diagrams, we have estimated the ages and metallicities of early type galaxies. We have found that the observed galaxies had recent star-formation mostly 5 <TEX>${\~}$</TEX> 7 Gyrs ago but the spread in age estimation is rather large. The average metallicities are [Fe/H]=0.l<TEX>${\~}$</TEX>0.5 dex. These results support the hypothesis that large early type galaxies in clusters are formed via hierarchical merging of smaller galaxies.
474
- CHEN ALFRED BING-CHIH
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.303-306
- 2005
- 원문 바로보기
Transient luminous events (TLEs; sprites, elves, jets and etc.) are lightning-related optical flashes occurring above thunderstorms. Since the first discovery of sprites in 1989, scientists have learned a great deal about the morphological, spectroscopic and electromagnetic characteristics of TLEs through ground and spacecraft campaigns. However, most of the TLE studies were based on events recorded over US High Plains. To elucidate the possible biasing effects, space-borne observations are needed and have their merits. Imager of sprites and Upper Atmospheric Lightning (ISUAL) on the FORMOSAT-2 satellite is the first instrument to carry out a true global measurement of TLEs from a low- earth orbit. In this short paper, we apply a common astronomical data analysis technique, two-color diagram, on the ISUAL spectrophotometer (SP) data. By choosing appropriated bandpasses and converting the measured flux of TLEs into the unit of magnitude, two-color diagrams of TLEs can be constructed. We demonstrate that two-color diagrams, which were constructed from the narrow-band spectrophotometer data, can be used to classify different types of TLEs and trace their temporal evolution. The amount of reddening due to Earth's atmosphere can also be estimated from two-color diagrams assembled from the broad-band spectrophotometer data.
475
- SAKAI TAKESHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.257-260
- 2005
- 원문 바로보기
We have mapped the W 3 giant molecular cloud in the <TEX>$C^o\;^3P_1-^3 P_o$</TEX> ([CI]) line with the Mount Fuji Submillimeter-wave Telescope. The [CI] emission is extended over the molecular cloud, having peaks at three star forming clouds; W 3(Main), W 3(OH), and AFGL 333. The [CI] emission is found to be strong in the AFGL 333 cloud. We have also observed the <TEX>$C^{18}O,\;CCS,\;N_2H^+$</TEX>, and <TEX>$H^{13}CO^+$</TEX> lines by using the Nobeyama Radio Observatory 45 m telescope. In the AFGL 333 cloud, we find two massive cores, which are highly gravitationally bound and have no sign of active star formation. The high [<TEX>$C^o$</TEX>]/[CO] and [CCS]/[<TEX>$N_2H^+$</TEX>] abundance ratios suggest that the AFGL 333 cloud is younger than the W 3(Main) and W 3(OH) clouds.
476
- NOUMARU JUNICHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.101-102
- 2005
- 원문 바로보기
Subaru Telescope proposes to hold Subaru East Asia Youth School (Tentative Name) in 2005.
477
- Choi, Seong-Hwan
- Journal of the Korean astronomical society = 천문학회지
- 38, n.4
- pp.463-470
- 2005
- 원문 바로보기
In this paper, we have made the component-based development of observational software for KASI solar imaging spectrograph (KSIS) that is able to obtain three-dimensional imaging spectrograms by using a scanning mirror in front of the spectrograph slit. Since 2002, the KASI solar spectrograph has been successfully operated to observe solar spectra for a given slit region as well as to inspect the response functions of narrow band filters. To improve its capability, we have developed the KSIS that can perform sequential observations of solar spectra by simultaneously controlling the scanning mirror and the CCD camera via Visual C++. Main task of this paper is to introduce the development of the component-based software for KSIS. Each component of the software is reusable on the level of executable file instead of source code because the software was developed by using CBD (component-based development) methodology. The main advantage of such a component-based software is that key components such as image processing component and display component can be applied to other similar observational software without any modifications. Using this software, we have successfully obtained solar imaging spectra of an active region (AR 10708) including a small sunspot. Finally, we present solar <TEX>$H{\alpha}$</TEX> spectra (<TEX>$6562.81{\AA}$</TEX>) that were obtained at an active region and a quiet region in order to confirm the validity of the developed KSIS and its software.
478
- UMETSU KEIICHI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.191-195
- 2005
- 원문 바로보기
We used Subaru observations of A1689 (z = 0.183) to derive an accurate, model-independent mass profile for the entire cluster, r<TEX>$\le$</TEX>2Mpc/h, by combining magnification bias and distortion measurements. The projected mass profile steepens quickly with increasing radius, falling away to zero at r<TEX>${\~}$</TEX>1.0Mpc/h, well short of the anticipated virial radius. Our profile accurately matches onto the inner profile, r <TEX>$\le$</TEX>200kpc/ h, derived from deep HST / ACS images. The combined ACS and Subaru information is well fitted by an NFW profile with virial mass, <TEX>$(1.93 \pm 0.20) {\times}10^{15} M_{\bigodot}$</TEX>, and surprisingly high concentration, <TEX>$C_{vir} = 13.7^{+1.4}_{-1.1}$</TEX>, significantly larger than theoretically expected (<TEX>$C_{vir} {\le}4$</TEX>), corresponding to a relatively steep overall profile. These results are based on a reliable sample of background galaxies selected to be redder than the cluster E/SO sequence. By including the faint blue galaxy population a much smaller distortion signal is found, demonstrating that blue cluster members significantly dilute the true signal for r <TEX>$\le$</TEX> 400kpc/ h. This contamination is likely to affect most weak lensing results to date.
479
- HIRANO NAOMI
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.219-222
- 2005
- 원문 바로보기
We present the high-resolution (2'-4') images of the molecular envelopes surrounding the evolved stars, V Hya, VY CMa, and <TEX>${\pi}^1$</TEX> Gru observed with the Submillimeter Array. The CO J=2-1 and 3-2 images of the carbon star V Hya show that the circumstellar structure of this star consists of three kinematic components; there is a flattened disk-like envelope that is expanding with a velocity of <TEX>${\~}16 km\;s^{-1}$</TEX>, the second component is the medium-velocity wind having a deprojected velocity of 40-120 km <TEX>$s^{-l}$</TEX> moving along the disk plane, and the third one is the bipolar molecular jet having an extreme velocity of 70-185 km <TEX>$s^{-l}$</TEX>. The axis of this high velocity jet is perpendicular to the plane of the disk-like envelope. We found that the circumstellar structure of the S-star <TEX>${\pi}^1$</TEX> Gru traced by the CO J =2-1 resembles that of V Hya quite closely; the star is surrounded by the expanding disk-like envelope and is driving the medium-velocity wind along the disk plane. We also obtained the excellent images of VY CMa with the CO and <TEX>$^{13}CO$</TEX> J=2-1 and <TEX>$SO\;6_5-5_4$</TEX> lines. The maps of three molecular lines show that the envelope has a significant velocity gradient in the east-west direction, suggesting that the envelope surrounding VY CMa is also flattened and expanding along its radial direction. The high-resolution images obtained with the SMA show that some AGB stars are associated with the asymmetric mass loss including the equatorial wind and bipolar jet.
480
- LIM JEREMY
- Journal of the Korean astronomical society = 천문학회지
- 38, n.2
- pp.237-240
- 2005
- 원문 바로보기
We present images of L1551 IRS5 at angular resolutions as high as <TEX>${\~}$</TEX>30 mas, corresponding to a spatial resolution of <TEX>${\~}$</TEX>5 AU, made at 7 mm with the VLA. Previously known to be a binary protostellar system, we show that L1551 IRS5 is likely a triple protostellar system. The primary and secondary components have a projected separation of <TEX>${\~}$</TEX>46 AU, whereas the tertiary component has a projected separation of <TEX>${\~}$</TEX>11 AU from the primary component. The circumstellar dust disks of the primary and secondary components have dimensions of <TEX>${\~}$</TEX>15 AU, whereas that of the tertiary component has a dimension of <TEX>${\~}$</TEX>10 AU. Their major axes are closely, but not perfectly, aligned with each other, as well as the major axis of the surrounding flattened, rotating, and contracting molecular condensation (pseudodisk). Furthermore, the orbital motion of the primary and secondary components is in the same direction as the rotational motion of this pseudodisk. We suggest that all three protostellar components formed as a result of the fragmentation of the central region of the molecular pseudo disk. The primary and secondary components, but apparently not the tertiary component, each exhibits a bipolar ionized jet that is centered on and which emergers perpendicular to its associated dust disk. Neither jets are resolved along their base, implying that they are driven within a radial distance of <TEX>${\~}$</TEX>2.5 AU from their central protostars. Finally, we show evidence for what may be dusty matter streams feeding the two main protostellar components.