• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.43-48
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• 2005

We present a high resolution spectrum of PU Vul observed at Bohyunsan Optical Astronomy Observatory (BOAO) on April 9, 2004. Permitted emission and nebular lines of PU Vul had been significantly changed compared to all spectra observed since its eruption in 1979. Therefore all new lines should be re-identified and were done so. We do-convoluted a $H{\beta}$ line into several emission components with Gaussian functions. Then we carefully discussed the geometrical feature of PU Vul in April 2004.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.94.1-94.1
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• 2014

We have carried out IGRINS test observations during its May commissioning run. Our targets were composed of three Luminous Blue Variables (LBVs), one supernova remnant (SNR), and an unidentified stellar source emitting [Fe II] 1.644 um line. In the preliminary results, three LBVs MWC 314, P Cygni, and AFGL 2298 show different characteristics: the spectrum of MWC 314 which is known to be in a binary system clearly shows double-peak structures in hydrogen and iron lines, the P Cygni spectrum reveals the Brackett series of hydrogen emission lines with prominent P-Cygni profiles, and AFGL 2298 likely at its visual minimum phase shows rather different spectrum with relatively weak hydrogen lines. The SNR (G11.2-0.3) was to test the sensitivity of IGRINS for diffuse emission. We successfully detected a dozen H2 emission lines with a velocity width of ~13 km/s, which might indicate a C-shock origin. The unidentified stellar source was one of stellar/compact sources of unknown nature detected in the survey of the Galactic plane in [Fe II] 1.644 um emission line (http://gems0.kasi.re.kr/uwife/). Its spectrum is under investigation. We will present the spectra of test observations and will discuss their scientific significance.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.59-64
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• 1998

Kim & Beuermann (1995, 1996)have developed a model for the propagation of X-rays from the accreting white dwarfthrough the infalling material and the re-emission of the energy deposited by photo-absorption in the optical (and UV) spectral range. By using this model, we calculate the profiles of the $H_{\gamma}$ emission-line spectrum of intermediate polars. Photoabsorption of X-ray by the infalling material is the dominant process in forming the observed energy-dependent rotational modulation of the X-ray flux. X-ray and optical modulations are sensitive to model parameters in different ways. In principle, these dependencies allow us to obtain improved insight into the accretion geometry of the intermediate polars. We present results of our calculations and compare them with the $H{\beta}$ line spectrum(Kim & Beuermann 1996).

• Journal of The Korean Astronomical Society
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• v.40 no.2
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• pp.39-47
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• 2007

A high resolution spectrum of PU Vul obtained at Bohyunsan Astronomy Observatory on April 9, 2004 is presented. At this phase, PU Vul was an emission-line star and its continuum was very weak. Emission lines of He II, H I, [Ne IV], [N II], [O III], [Ar V ] and [Fe VII] dominated the spectrum of PU Vul. Many of them exhibited hat-top profiles with strong and multi-peaked emissions on flat-tops of their profiles. Radial velocities for these lines were measured. Origins of the spectral lines are discussed in terms of the wind and the photoionization models.

• Journal of The Korean Astronomical Society
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• v.47 no.4
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• pp.147-152
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• 2014

We present measurements of the Fe $K{\alpha}$ emission line of the intermediate polar V1223 Sagittarii observed with the Suzaku satellite. The spectrum is modeled with an absorbed thermal bremsstrahlung spectrum and three Gaussians for the three components of the Fe $K{\alpha}$ lines. We resolve the neutral or low-ionized (6.41keV), He-like (6.70keV), and H-like (7.00keV) iron lines. We also obtain a thermal continuum temperature of 25 keV, which supports a thermal origin of the hard X-rays observed from the shock heated layers of gas between the white dwarf and the shock front. Hence, we believe that the He-like and H-like lines are from the collisional plasma. On the origin of the Fe $K{\alpha}$ fluorescence line, we find that it could be partly from reflections of hard X-rays from the white dwarf surface and the $N_H$ absorption columns. We also discuss the Fe $K{\alpha}$ emission line as veritable tool for the probe of some astrophysical sites.

• Journal of The Korean Astronomical Society
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• v.37 no.2
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• pp.87-90
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• 2004

Spectrophotometry of the night sky over Mount Bohyun is presented for the nearly entire visible wavelengths of $3600{\~}$8600{\AA}$. The data was obtained under moonless clear sky in February 2004 with the 1.8-m telescope and the long slit spectrograph. The sky spectrum shows a number of strong emission lines originated from light pollution, especially due to high pressure sodium lamps. When compared to the night sky of Kitt Peak, our sky continuum is 1 to 2 magnitude brighter at all wavelengths, the worst being around the broad emission region near 6000${\AA}$. The night sky spectrum presented here with almost complete line identifications is a useful reference for arc-independent wavelength calibrations to check the gravity flexure of the spectrograph and the wavelength shift between FeNeArHe arc frames and science frames.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.133-145
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• 2000

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., $OVI{\lambda}6830.\;The\;OVI{\lambda}6830$ emission lines are also found in S-type symbiotics, which have been known as charateristics of D-types.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.61-71
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• 2000

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.

• Journal of The Korean Astronomical Society
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• v.36 no.2
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• pp.55-60
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• 2003

In Lee, Kang & Byun (2001) the discovery of Raman scattered 6545 A feature was reported in symbiotic stars and the planetary nebula M2-9. The broad emission feature around 6545 A is formed as a result of Raman scattering of He II n = 6 $\to$ n = 2 photons by atomic hydrogen. In this paper, we introduce a method to compute the equivalent width of He II $\lambda$ 1025 line and present an optical spectrum of the symbiotic star RR Telescopii as an example for a detailed illustration. In this spectrum, we pay attention to the broad H$\alpha$ wings and the Raman scattered He II 6545 feature. The broad Ha wings are also proposed to be formed through Raman scattering of continuum around Ly$\beta$ by Lee (2000), and therefore we propose that the equivalent width of the He II $\lambda$ 1025 emission line is obtained by a simple comparison of the strengths of the 6545 feature and the broad H$\alpha$ wings. We prepare a template H$\alpha$ wing profile from continuum radiation around Ly$\beta$ with the neutral scattering region that is supposed to be responsible for the formation of Raman scattered He II 6545 feature. Isolation of the 6545 feature that is blended with [N II] $\lambda$ 6548 is made by using the fact that [N II] $\lambda$ 6584 is always 3 times stronger than [N II] $\lambda$ 6548. We also fit the 6545 feature by a Gaussian which has a width 6.4 times that of the He II $\lambda$ 6527 line. A direct comparison of these two features for RR Tel yields the equivalent width $EW_{Hel025} = 2.3{\AA}$ of He II $\lambda$ 1025 line. Even though this far UV emission line is not directly observable due to heavy interstellar extinction, nearby He II lines such as He II $\lambda$ 1085 line may be observed using far UV space instruments, which will verify this calculation and hence the origins of various features occurring in spectra around H$\alpha$.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.113-118
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• 2000

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.