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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Publications of The Korean Astronomical Society
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The Korean Astronomical Society
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Volume & Issues
Volume 15, Issue spc2 - Dec 2000
Volume 15, Issue spc1 - Aug 2000
Volume 15, Issue 1 - Jun 2000
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SPECTRA OF HII REGIONS IN SPIRAL GALAXIES AND GALACTIC GLOBULAR CLUSTERS
CHUN MUN-SUK ; SOHN YOUNG-JONG ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 1~13
We review the early historical developement of astronomical spectrographs, properties of emission line spectra of HII regions in spiral galaxies, and absorption line features of galactic globular clusters. Emission line spectra of HII regions within three spiral galaxies NGC 300, NGC 1365, and NGC 7793, which were observed from AAT/IPCS, had been analysed, and we discuss the abundances of elements in HII regions and the radial abundace gradients through the galaxies. The radial UBV color variations of two globular clusters, NGC 1851 and NGC 2808, were examined for correlations with radial variations of several absorption lines in the integrated spectra, which were obtained from SAAO 74 inch telescope and image tube spectrograph. Nine giant star's spectra in NGC 3201 were also obtained and analysed for the radial abundance gradients in the globular cluster. The results show that the presence of a radial color gradient in a globular cluster is correlated with the presence of abundance gradients. Finally, we suggest some scientific programs for the new high dispersion spectrograph, which will be installed to the BOAO 1.8m telescope.
SPECTROSCOPIC STUDY ON RED GIANTS IN GLOBULAR CLUSTERS
LEE SANG-GAK ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 15~30
A large scatter of the chemical abundances among globular cluster red giants has been observed. Especially the chemical elements C, N, O, Na, Mg, and Al vary form star to star within globular clusters. Except for
Cen and M22, most globular clusters could be considered to be monometallic of their iron peak elements within error ranges. The variations in light elements among globuar cluster giants appear much more pronounced than in field halo giants of comparable Fe-peak metallicity. It has been found that in general the nitrogen abundance is anticorrelated with both carbon and oxygen, while it is correlated with Na and AI. These intracluster abundance inhomogeneities can be interpreted either by mixing of nucleosythesized material from the deep stellar interior during the red giant branch phase of evolution or by inhomogeneities of primordially processed material, from which the stars were formed. The simple way of distingushing between two senarios is to obtain the element abundances of main-sequence stars in globular clusters, which are too faint for high resolution spectroscopic studies until now. Both 'evolutionary' and 'primodial' origins are accepted for explanations of abundance variations among red giants and CN-CH anticorrelations among main-sequence stars in globular clusters. This paper reviews chemical abundances of light elements among globular cluster giants, with brief reviews of cannonical stellar evolution of low mass stars after main-sequence and deep mixing for abundance variations of cluster giants, and a possible connection between deep mixing and second parameter.
SPECTROSCOPY OF PLANETS AND COMETS
KIM SANG JOON ; LEE YOUNG SIEK ; YI YU ; KIM YOUNG HA ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 31~38
We have presented detected molecules, atoms, radicals, ions, and dimers in the atmospheres of planets and comets from Earth-based and spaceborne observatories during the last 3 decades. We have reviewed spectroscopic studies on the auroral emissions and air glows of the giant planets, and briefly summarized spectroscopic observations of dimers in the atmospheres of the giant planets and Titan. In particular, we highlighted the recent detections of new molecular emissions and absorptions in the spectra of the giant planets, Titan, and recent bright comets from spaceborne or ground-based observatories. We also reviewed current models and theories of the origin and evolution of the solar system, and implications of isotopic ratios in these atmospheres.
LONG-SLIT SPECTROSCOPY FOR EXTENDED OBJECTS
SUNG EON-CHANG ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 39~60
We will discuss two-dimmensional spectrophotometry including long-slit spectroscopy and narrow-band imaging. The basic principles, applications, and techniques of observations and data reduction of spectroscopy and spectrophotometry for extended objects are described. This discussion will focus on practical long-slit spectroscopy using a Cassegrain spectrograph attached with 2 or 4m class telescopes and on imaging spectrophotometry using narrow-band interference filter sets. We will discuss scientific applications.
EMISSION LINE SPECTROSCOPY WITH THE 1.8M OPTICAL TELESCOPE
HYUNG SIEK ; ALLER LAWRENCE H. ; KIM KANG-MIN ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 61~71
The emission line objects such as planetary nebulae, symbiotics, gaseous nebulae, HII regions, novae, supernovae, SNRs, nearby spiral galaxies, dIrr, dE, and nearby active galactic nuclei, would be goldmines for us to dig with the 1.8m bohyunsan optical (BOAO) telescope. We discussed the importance of strategically important diagnostic lines and atomic constant calculation for a study of Galactic and extragalactic emission objects. The scientific background on a spectrometer development history is briefly presented and spectroscopic research areas other than the emission objects are also summarized.
SPECTROSCOPIC STUDIES IN X-RAY ASTRONOMY
CHOI CHUL-SUNG ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 73~83
X-ray astronomy deals with measurements of the electromagnetic radiation in the energy range of
. The wavelength of X-ray is comparable to the size of atoms, so that the photons in the X-ray range are usually produced and absorbed by the atomic processes. Since the launch of the first X-ray astronomy satellite 'Uhuru' in 1970, technological advances in a launch capability and a detection capability make X-ray astronomy one of the most rapidly evolving fields of astronomical research. Particularly, a spectral resolving power
has been increased by an order of 2 - 3 (in the energy range of 0.1 - 10 keV) during the past 30years. In this paper, I briefly review a developing process of the resolving power and spectroscopic techniques. Then I describe important emission/absorption lines in X-ray astronomy, as well as diagnostics of gas property with line parameters.
INFRARED SPECTROSCOPIC ASTRONOMY OF STARS AND GALAXIES
SUH KYUNG-WON ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 85~91
Infrared spectroscopic observations and their analysis revealed many physical and chemical characteristics of the various stars with dust envelopes. Especially, AGB stars and young stellar objects are believed to be major contributors of infrared radiation from galaxies. The wavelength of the peak spectral energy for typical galaxies is about
. Therefore, infrared spectral observations of galaxies provide important information for their overall properties. The qualitative analysis of the infrared spectra which are made of various stars and interstellar matter will be possible through a new population synthesis.
SPECTRA OF CHROMOSPHERICALLY ACTIVE STARS
KANG YOUNG WOON ; KIM HOIL ; LEE WOO BAIK ; OH KYU DONG ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 93~102
We have reviewed the magnetic activity in close binaries. Solar like magnetic activity indicators such as photometric spots, chromo spheric emission, coronal X-ray and radio emission, and flare activity are commonplace in many cool stars with convective envelopes. Using the UV spectra we confirmed the strength of stellar activity increases with more rapid rotation and later spectral types which corresponds to the increasing depth of the star's convective envelope. Apart from very young stellar objects such as T Tauri stars, the stars with the highest levels of activity are close binary systems composed of cool stars, i.e., the chromospherically active binaries such as RS CVn, BY Dra, W UMa and related systems. The IUE low and high dispersion spectra of V711 Tau, VW Cep and SW Lac are used for ultraviolet photometry and for a variation study of chromospheric activity. Evidence of chromospherically activity is indicated by the intensity variation of the Mg II emission line with orbital phase.
RAMAN SPECTROSCOPY IN SYMBIOTIC STARS
LEE HEE-WON ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 103~112
Symbiotic stars are known as binary systems of a giant with heavy mass loss and a white dwarf accompanied by an emission nebula. They often show bipolar nebulae, and are believed to form an accretion disk around the white dwarf component by attracting the slow but heavy stellar wind around the giant companion. However, the existence and physical properties of the accretion disk in these systems still remain controversial. Unique to the spectra of symbiotic stars is the existence of the symbiotic bands around
, which have been identified by Schmid (1989) as the Raman scattered features of the O VI
doublet by atomic hydrogen. Due to the incoherency of the Raman scattering, these features have very broad profiles and they are also strongly polarized. In the accretion disk emission model, it is expected that the Raman features are polarized perpendicular to the binary axis and show multiple peak structures in the profile, because the neutral scatterers located near the giant component views the accretion disk in the edge-on direction. Assuming the presence of scattering regions outflowing in the polar directions, we may explain the additional red wing or red peak structure, which is polarized parallel to the binary axis. We argue that in the accretion disk emission model it is predicted that the profile of the Raman feature around
is different from the profile of the
because the O VI line optical depth varies locally around the white dwarf component. We conclude that the Raman scattered features are an important tool to investigate the physical conditions and geometrical configuration of the accretion disk in a symbiotic star.
LINE EMISSION FROM THE MAGNETOSPHERE OF MAGNETIC CATACLYSMIC VARIABLES
KIM YONGGI ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 113~118
A magnetic cataclysmic variable has a rotating magnetic white dwarf which accretes matter from its late type companion. Kim & Beuermann (1995) presented a phenomenological model of the accretion from its surrounding structure e.g., a disk into the magnetosphere of the white dwarf, and presented results for the spin modulated X-ray spectrum and light curves. Using this model, we calculate the optical continuum and line emission which result from reprocessing of X-rays in the accretion stream within the magnetosphere. Penning (1985) suggested the observed spin-modulated radial-velocity variations might result from reprocession of X-rays in the disk. We, however, find the radiation can be originated from the magnetosphere accretion stream. We use the same geometrical model to calculate the optical and the X-ray behaviour. The results from the two wavelength bands are internally consistent. We conclude that this approach will increase the diagnostic accuracies of the results.
CONSTRUCTION OF THE BOAO ECHELLE SPECTROGRAPH (BOES)
KIM KANG-MIN ; JANG JEONG GYUN ; CHUN MOO-YOUNG ; PARK BYEONG-GON ; HYUNG SIEK ; HAN INWOO ; YOON TAE SEOG ; VOGT STEVEN S. ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 119~126
The BOES (BOAO Echelle Spectrograph), a fiber-fed echelle spectrograph of the BOAO 1.8 m telescope, has been designed and now is being manufactured. The BOES follows a white pupil design collimated with two off-axis parabolic mirrors. The 136mm collimating beam leaving the 41.59 grooves/mm R4 echelle grating is refocused near the narrow folding mirror. Through the two cross-disperser prisms and
transmission camera, the beam images on EEV
CCD. The BOES can take the wavelength range of 3700 to
at a single spot with spectral resolution R = 20000 to 40000 depending on the fiber set employed. We describe the key sciences and performance, current status of construction, and future plan of the BOES.
FABRY-PEROT SPECTROMETER IN ASTRONOMY
PAK SOOJONG ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 127~132
The purposes of spectroscopy in astronomy are to measure the radiation flux of the spectroscopic emission or absorption line and to measure the dynamical parameters of the line profile. In order to use an appropriate instrument for the scientific purpose, we need to understand the characteristics of various spectrometers, e.g., a prism spectrometer, a grating spectrometer, and a Fabry-Perot spectrometer (FPS), which are being used in ultra-violet, optical, and infrared bands. The FabryPerot spectrometer is not very popular compared to the grating spectrometer, because of its complex and tricky operations. The Fabry-Perot spectrometer, however, can get a two-dimensional image at one exposure, so we can study radiation mechanisms and dynamical properties of extended sources, e.g., clusters, nebula, and galaxies.
THE SPECTROSCOPIC CHARATERISTICS OF 23 SYMBIOTICS
KIM YEOJEONG ; HYUNG SIEK ; ALLER LAWRENCE H. ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 133~145
Symbiotic stars are known as binary systems with both cool and hot components with enshrounding nebulous gas. The cool component, M-type giant, is presumably loosing its mass into a hot white or main sequence companion star through the inner Lagrangian point. The lines emit from the ionized nebulous region around the hot star while the mass loss or accretion activity is believed to be the main cause of sudden variation of the continuum and line fluxes. We selected 17 symbiotics for which the emission line fluxes were measured from the IUE SWP, LWR data, to find variability of spectrum. We also investigated the periodic variation of emissions or eclipsing effect from the IUE lines. All of our symbiotics show very high electron densities in the emission regions. For other optical symbiotics, the observations had been carried in 1999 with BOAO mid-resolution spectrometer. We classified symbiotics based on their outburst activities, or emission line characteristics, i.e.,
emission lines are also found in S-type symbiotics, which have been known as charateristics of D-types.
WINGS RAMAN-SCATTERED IN SYMBIOTIC STARS
BAK JIH-YONG ; LEE HEE-WON ;
Publications of The Korean Astronomical Society, volume 15, issue spc1, 2000, Pages 147~151
Symbiotic stars, believed to be binary systems of a mass-losing giant and a white dwarf with an emission nebula, are known to exhibit very broad wings around Hex that extend to
. The wing formation mechanism is not a settled matter and recently Lee (2000) proposed that Raman scattering of Ly
by neutral hydrogen is responsible for the broad H
wings. In this model, it is predicted that. the Hex wings will be polarized depending on the geometric and kinematic distribution of the scatterers relative to the UV emission region. In this paper, we investigate the polarization of Hex wings in symbiotic stars. Noting that many symbiotic stars possess bipolar nebular morphology, we assume that the distribution of neutral scatterers follows the similar pattern with a receding velocity of several tens of km
that mimics the expansion of the neutral envelope of the nebula. It is found that the red wing is more strongly polarized than the blue and main part and that the polarization direction is along the equatorial plane. We obtain a typical degree of polarization
percent, however, it varies depending on the detailed distribution of H I scatterers We conclude that spectropolarimetry will provide very important information on the origin of the Hex wings.