• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.32.4-32.4
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• 2010

Evolution of the Cosmos (ARCSEC). We have presented the evolutionary status of seven detached double line spectroscopic eclipsing binaries which are CD Tau, CM Lac, CW CMa, HS Hya, IT Cas, KM Hya, and ZZ Boo because the component stars in the binary systems still act as a single star. We determined the absolute dimensions of the binary systems using photometric and spectroscopic solutions by analyzing of the light curves and radial velocity curves. We chose evolutionary tracks of these binary systems. Using the luminosities, effective temperatures and masses. Finally we obtained ages and metallicity of the stars.

• 천문학회보
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• 제39권2호
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• pp.95-95
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• 2014

The mass measurement of neutron stars or black holes is of fundamental importance in our understanding of the evolution of massive stars and core-collapse supernova explosions as well as some exotic physics of the extreme conditions. Despite the importance, however, it's very difficult to measure mass of these objects directly. One way to do this, if they are in binary systems, to measure their binary motions (i.e., Doppler shifts) which can give us direct information on their mass. Recently many new highly-obscured massive X-ray binaries have been discovered by new hard X-ray satellites such as INTEGRAL and NuSTAR. The new highly-obscured massive X-ray binaries are faint in the optical, but bright in the infrared with many emission lines. Based on the near-infrared spectroscopy, one can first understand the nature of stellar companions to the compact objects, determining its spectral types and luminosity classes as well as mass losses and conditions of (potential) circumstellar material. Next, spectroscopic monitoring of these objects can be used to estimate the mass of compact objects via measuring the Doppler shifts of the lines. For the former, broad-band spectroscopy is essential; for the latter, high-resolution spectroscopy is critical. Therefore, IGRINS appears to be an ideal instrument to study them. An IGRINS survey of these new highly-obscured massive X-ray binaries can give us a rare opportunity to carry out population analyses for understanding the evolution of massive binary systems and formation of compact objects and their mass ranges. In this talk, we will present a sample near-infrared high resolution spectra of HMXB, IGR J19140+0951 and discuss about its spectral feature. These spectra are obtained on 13th July, 2014 from IGRINS commissioning run at McDonald 2.7m telescope. And at final, we will introduce the upgrade plan of IGRINS Operation Software (IGOS), to gather the input from IGRINS observer.

• 천문학회보
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• 제35권1호
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• pp.50.1-50.1
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• 2010

We have analyzed times of minima for of 6 binary systems. Three binary systems show period decrease at rate $3.19{\times}10-5$ yr -1 for SV Cen, $1.35{\times}10-7$ yr -1 for RT Scl and $1.14{\times}10-7$ yr -1 for AD Phe. Two systems show period increase $5.696{\times}10-8$ yr -1 for SX Aur and $6.93{\times}10-8$ yr -1 for GO Cyg. One system shows cyclic period variation. We estimated the mass transfer rate for 5 binary systems. Four systems show asymmetric light curves. Two asymmetric light curves (SV Cen and RT Scl) are due to hot spot caused by mass transfer. And two asymmetric light curves (AD Phe and TY Boo) are due to cool spot caused by magnetic activities on the cooler component. We also obtain absolute dimensions from photometric solution and spectroscopic solution by analyzing their light curves and radial velocity curves, which are collected from literatures, using 2007 version Wilson and Deviney computer code.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.32.3-32.3
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• 2010

We have analyzed times of minima for six eclipsing binary systems which show asymmetric light curves. We found that five binary systems show period decrease and one system shows cyclic period variation. Three asymmetric light curves (SV Cen, RT Scl and VW Boo) are due to hot spot caused by mass transfer. Other three asymmetric light curves (AD Phe,, EZ Hya and TY Boo) are due to cool spot on the cooler component caused by magnetic activities. We also obtain absolute dimensions from photometric solution and spectroscopic solution by analyzing their light curves and radial velocity curves, collected from literatures, using 2007 version Wilson and Devinney computer code.

• Journal of Astronomy and Space Sciences
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• 제22권3호
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• pp.223-232
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• 2005

질량비가 작은 접촉쌍성 V410 Aur과V776 Cas를 소백산천문대의 61cm망원경에 2K CCD 카메라를 부착하여 측광 관측을 하였으며, 그 결과 이 별들의 새로운 3색(BVR)의 완전한 광도곡선을 얻었다. 새로운 광도곡선과 이미 발표된 분광관측으로부터 WD모델을 이용하여 이 두 별의 궤도요소와 절대 물리량을 얻었다. V410 Aur과 V776 Cas를 포함한 절대물리량이 잘 알려진 19개의 질량비가 작은 접촉쌍성들의 진화 상태를 조사하였다. 그 결과 질량비가 작은 접촉쌍성의 주성은 대부분 TAMS상에 놓이며 반성은 ZAMS 아래 놓이고 있음을 재확인하였다.

• Journal of Astronomy and Space Sciences
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• 제23권3호
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• pp.189-198
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• 2006

BVRI CCD 측광 관측에 의하여 질량비가 작은 접촉쌍성 HN UMa와 II UMa의 새로운 광도곡선을 얻었다. 새로운 광도곡선과 이미 발표된 분광관측으로부터 Wilson-Devinney 프로그램을 이용하여 이 두 별의 궤도요소와 절대 물리량을 얻었다. HN UMa와 II UMa를 포함한 절대물리량이 잘 알려진 21개의 질량비가 작은 접촉쌍성들의 진화 상태를 조사하였다. 그 결과 질랑비가 작은 접촉쌍성의 반성은 영년주계열 아래 놓이며, 이러한 현상은 질량이 작은 접촉쌍성의 반성에서의 질량손실을 가정할 경우, 비록 작의 양의 질량이지만 반성에서의 질량 감소는 상대적으로 광도의 감소가 현저히 작아지기 때문일 것으로 예상된다.

• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.75-82
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• 2017

High-resolution spectroscopic observations of the eclipsing binary system RR Lyn were made using the 1.8 m telescope at the Bohuynsan Optical Astronomical Observatory in Korea. The spectral resolving power was R = 82,000, with a signal to noise ratio of S/N > 150. We found the effective temperatures and surface gravities of the primary and secondary components to be equal to $T_{eff}$ = 7,920 & 7,210 K and log(g) = 3.80 & 4.16, respectively. The abundances of 34 and 17 different chemical elements were found in the atmospheric components. Correlations between the derived abundances with condensation temperatures and the second ionization potentials of these elements are discussed. The primary component is a typical metallic line star with the abundances of light and iron group elements close to solar values, while elements with atomic numbers Z > 30 are overabundant by 0.5-1.5 dex with respect to solar values. The secondary component is a ${\lambda}$ Boo type star. In this type of stars, CNO abundances are close to solar values, while the abundance pattern shows a negative correlation with condensation temperatures.

• 천문학회지
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• 제41권2호
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• pp.23-37
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• 2008

The high-resolution optical region spectroscopic data of the symbiotic nova AG Peg secured with the Hamilton Echelle Spectrograph at the Lick Observatory, have been analyzed along with the International Ultraviolet Explorer UV archive data. We measure about 700 line intensities in the wavelengths of 3859 to $9230{\AA}$ and identify about 300 lines. We construct pure photoionization models that represent the observed lines and the physical condition for this symbiotic nova. The spectral energy distribution of the ionizing radiation is adopted from stellar model atmospheres. Based on photoionization models, we derive the elemental abundances; C & N appear to be similar to be smaller than the Galactic planetary nebular value while O is enhanced. Our result is compared with the Contini (1997, 2003) who analyzed the UV region spectral data with the shock + ionization model. The Fe abundance appears to be enhanced than that of normal planetary nebulae, which suggests that AG Peg may have formed in the Galactic disk. The models indicate that the temperature of the central star which excite the shell gas may have fluctuated to an unexpected extent during the years 1998 - 2002.

• 천문학회보
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• 제44권1호
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• pp.46.3-46.3
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• 2019

We present our observational and theoretical investigation of Raman-scattered features in symbiotic stars (SySts). SySts are long interacting binaries, consisting of a hot compact star and an evolved giant, whose interaction via accretion process is at the origin of a tangled network of gas and dust nebulae. These systems are ideal objects to study a variety of important astrophysical problems, and have also been proposed as possible progenitors of type Ia supernova. In this talk, we emphasize that Raman-scattered features are exclusive spectroscopic tools to probe the stellar wind accretion processes in SySts. We studied mass transfer and mass loss processes in SySts using high resolution spectra obtained with 1.8m telescope at Mt. Bohyun and the 6.5m Magellan-Clay telescope combining with the theoretical modeling of radiative transfer of Raman-scattered features. We also note that there are a much smaller number of SySts known in our Galaxy, implying the necessity of systematic search programs. In view of the fact that Raman O VI features at $6830{\AA}$ are found in only bona fide SySts, we will carry out a photometric search of objects with Raman O VI features using a narrow band filter centered at $6830{\AA}$ in Local group galaxies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.288.1-288.1
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• 2014

We investigated the optical properties of Ge1-xSex and Ge1-x-ySexAsy amorphous semiconductor films using spectroscopic ellipsometry and Raman spectroscopy. The dielectric functions and absorption coefficients of the amorphous films were determined from the measured ellipsometric angles. We obtained the optical gap energies and Urbach energies from the absorption coefficients, and found a strong bowing effect in the optical gap energy of Ge1-x-ySexAsy where the endpoint binaries were Ge0.50Se0.50 and Ge0.31As0.69. Based on the correlation between optical gap energies and Urbach energies, the large bowing parameter was attributed to the electronic disorder. We found the composition dependence of several phonon modes using Raman spectroscopy. For Ge1-x-ySexAsy, the D mode (232-267 cm-1) changed from As-As (or As3 pyramid), to As(Se1/2)3 pyramid, and finally to Se clusters, as the Se composition increased. Resonant Raman phenomenon was observed in Ge0.38Se0.62 at a laser excitation of 514 nm (2.41 eV). We verified that this laser energy corresponds to the transition energy of Ge0.38Se0.62 using the second derivative of the dielectric function of Ge0.38Se0.62.