• 천문학회보
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• 제38권1호
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• pp.59.2-59.2
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• 2013

Wilson and Bappu found a tight correlation between the stellar absolute visual magnitude (MV) and the width of the Ca II K emission line for late-type stars in 1957. Here, we revisit the Wilson-Bappu relationship (hereafter, WBR) to claim that WBR can be an excellent indicator of stellar surface gravity of late-type stars as well as a distance indicator. We have measured the width (W) of the Ca II K emission line in high resolution spectra of 125 late-type stars, which were obtained with Bohyunsan Optical Echelle Spectrograph (BOES) and adopted from the UVES archive. Based on our measurement of the emission line width (W), we have obtained a WBR of $M_V=33.76-18.00{\log}W$. In order to extend the WBR to be a surface gravity indicator, the stellar atmospheric parameters such as effective temperature ($T_{eff}$), surface gravity (logg), metallicity ([Fe/H]), and micro-turbulence (${\xi}_{tur}$) have been derived from the self-consistent detailed analysis using the Kurucz stellar atmospheric model and the abundance analysis code, MOOG. Using these stellar parameters and logW, we found that ${\log}g=-5.85\;{\log}W+9.97\;{\log}T_{eff}-23.48$ for late-type stars.

• 천문학회보
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• 제38권1호
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• pp.59.1-59.1
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• 2013

HBC722 (also known as LkHa 188-G4 and PTF 10qpf; A. Miller et al., 2011) is one of the FU Orionis-like young stellar objects which outbursted in August 2010 (Semkov et al., 2010). We have been monitoring the post-outburst phase of this object since November 2010 with Korean Astronomy and Space Science Institute Near Infrared Camera System (KASINICS), at Bohyunsan Optical Astronomy Observatory (BOAO). Four filters, J, H, Ks, and H2 band, were used for this observation. We did aperture photometry to find photometric variation. The light curve shows a long period brightness change. After decrease of the brightness, which was reported at the KAS 2011 fall meeting, HBC722 brightens up slowly now. However we cannot confirm any short period variations, previously reported by Green et al (2013), due to large scatters in the obtained light curve.

• 천문학회보
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• 제41권1호
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• pp.32.1-32.1
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• 2016

1996년, 보현산천문대는 1.8m 반사망원경과 1K CCD 카메라, 그리고 태양망원경을 갖추고 한국 천문학의 본격적인 광학관측시대를 열었다. 준공 직후인 1997년에는 측광관측기기를 2K CCD로 교체 하였으며, 1998년에는 망원경 제어시스템(TCS)을 국내 연구진이 자체 개발하였고 망원경의 전자부도 교체하였다. 1999년의 중분산분광기 제작 이후 2003년에는 고분산에셀분광기 BOES를 개발하여 세계적인 경쟁력을 갖춘 분광관측이 가능하게 되었다. BOES는 현재 보현산천문대의 주 관측기기로 활용 중이다. 2008년에는 적외선이미징카메라 KASINICS를 개발하여 관측 파장대를 적외선까지 넓혔으며, 2010년에는 가시광 측광관측기기를 4K CCD로 업그레이드 하였다. 2015년에는 망원경 구동시스템을 다시 한 번 개선하여 보다 안정적이고 정밀한 관측시스템을 갖추게 되었다. 또한, 2014년과 2015년에는 2년에 걸쳐 관측실과 숙소, 그리고 각종 연구시설의 전면 리모델링을 실시하여 관측자를 위한 환경도 개선하였다. 이러한 다양한 관측지원을 바탕으로 보현산천문대 연구장비를 활용한 논문은 매년 꾸준히 생산되고 있으며 관측과 연구결과들은 한국 광학천문학의 밑거름이 되고 있다. 2016년에는 1m 망원경 설치를 완료할 예정이며 장기관측 과제에 집중함으로써 연구의 새로운 지평을 열게 될 것이다. 연구장비의 안정적인 구동과 성능 향상을 위해 중장기발전계획 아래 노후화된 기기의 교체와 개발을 진행 중이다. 2016년 4월, 제2의 도약기를 준비 중인 보현산천문대의 준공 20주년을 맞이하여, 그 동안의 발자취를 돌아보고 앞으로 나아갈 길을 제시하고자 한다.

• 천문학회보
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• 제44권1호
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• pp.83.3-83.3
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• 2019

New high-resolution spectra and multi-band photometric data of BS Cas were obtained at the Bohyunsan Optical Astronomy Observatory in 2018 and at the Jincheon Station of the Chungbuk National University Observatory in 2011, respectively. We measured the radial velocities (RVs) for both components, and the effective temperature of the more massive star was determined to be $6262{\pm}56K$. In addition, historical light curves showed strong time-dependant light variations at the total eclipse. These variations were modeled by a cool spot on the more massive component. Finally, the physical parameters of BS Cas by a simultaneous analysis of our RV curves with the photometric light curves were presented. Individual masses and radii of both components were deduced as $M_1= 0.59{\pm}0.07M_{\odot}$, $M_2=1.47{\pm}0.15M_{\odot}$, $R_1=0.94{\pm}0.03R_{\odot}$ and $R_2=1.47{\pm}0.05R_{\odot}$.

• 천문학논총
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• 제37권2호
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• pp.13-31
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• 2022

We observed the symbiotic star AG Dra for a total of 61 nights between April 2004 and December 2021 using the 1.8-m telescope and the high-resolution Echelle spectrograph BOES at the Bohyunsan Optical Astronomy Observatory and obtained 355 frames of spectroscopic data to investigate the variations in its spectral lines. Overnight short-term and long-term changes in prominent emission lines are examined. No short-term changes are found in the line profiles. However, the peak intensity of the Hα emission line exhibits very small variation. In the long-term period, many emission lines including He I λ5875, λ6678, λ7065 and Fe II λ5018 are found to vary reflecting the symbiotic outburst activities. It is noted that He II λ4686 and Raman-scattered O VI λ6830, λ7088 are exceptions, where no significant variations are discernible. One of the noticeable lines is the λ5018 line. Its appearance and disappearance pattern are different from other emission lines, and the line is found to appear in outburst states. The Hα and Hβ lines remain very similar in our spectroscopic monitoring campaign.

• 천문학회보
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• 제46권2호
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• pp.76.2-76.2
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• 2021

We present the characterization of the performance of the next-generation controller (SDSU Gen III) for BOAO Echelle Spectrograph CCD (BOES CCD) at the Bohyunsan Optical Astronomy Observatory. The current controller (SDSU Gen II) of the BOES CCD will be upgraded to SDSU Gen III to provide a more stabilized operation. To assess the performance of the new controller (e.g., conversion gain, full well capacity, S/N), we obtain various types of calibration images (e.g., bias, flat, science images of standard stars). Based on those datasets, we find that the overall performance of the new controller is somewhat comparable to that of the old controller if the slow mode is adopted for the readout. This may demonstrate that the new controller can be successfully substituted for the old controller without a substantial loss of performance. However, further analysis with a large dataset obtained in various observational conditions is necessary to confirm our results.

• 천문학회지
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• 제56권1호
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• pp.35-40
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• 2023

We have been conducting a exoplanet search survey using Bohyunsan Observatory Echelle Spectrograph (BOES) for the last 18 years. We present the detection of exoplanet candidate in orbit around HD 18438 from high-precision radial velocity (RV) mesurements. The target was already reported in 2018 (Bang et al. 2018). They conclude that the RV variations with a period of 719 days are likely to be caused by the pulsations because the Lomb-Scargle periodogram of HIPPARCOS photometric and H_α EW variations for HD 18438 show peaks with periods close to that of RV variations and there were no correlations between bisectors and RV measurements. However, the data were not sufficient to reach a firm conclusion. We obtained more RV data for four years. The longer time baseline yields a more accurate determination with a revised period of 803 ± 5 days and the planetary origin of RV variations with a minimum planetary companion mass of 21 ± 1 M_Jup. Our current estimate of the stellar parameters for HD 18438 makes it currently the largest star with a planetary companion.

• Current Research on Agriculture and Life Sciences
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• 제33권2호
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• pp.37-40
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• 2015

Poria cocos is an edible and pharmaceutical mushroom with a long history of medicinal use in Korea. For the last 30 years, the domestic cultivated supply of Poria cocos has been unable to meet consumer demand, so Poria cocos is collected in mountainous areas and also imported from China. Thus, to increase the supply of Poria cocos, many artificial cultivation methods have been studied. In this study, Poria cocos is cultivated under different environmental conditions using plastic bags and the results compared. When cultivating Poria cocos at different temperatures (20, 25, 30 and $35^{\circ}C$) and using different numbers of plastic bag layers (1, 2), the most efficient cultivation conditions were a temperature of $25-30^{\circ}C$ and 2 plastic bag layers. The fastest growth was at $25-30^{\circ}C$, and the Poria cocos exhibited no weight change when cultivated using layers of plastic bags (1, 2).

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.453-466
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• 2004

한국천문연구원에서는 적외선관측기술 개발의 일환으로 지상망원경용 근적외선 카메라인 KAONICS(KAO Near-Infrared Camera System)를 개발하고 있다. 이러한 개발의 선행 연구 과정으로서 우리는 보현산천문대와 소백산천문대의 근적외선($1-5{\mu}m$) 관측 조건을 정량적으로 조사했다. KAONICS의 기본 파장 밴드인 J, H, K, L 에 대해 대기 투과 모델을 사용하여 PWV(Precipitable Water Vapour)에 따른 대기투과율을 계산했으며, 각각의 파장 밴드에서 관측 한계 등급을 계산했다. 계산 결과, 두 천문대 모두 근적외선 영역에서 관측이 가능하며, 서로 비슷한 관측 능력을 가지고 있다는 결론을 얻었다.

• Journal of Astronomy and Space Sciences
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• 제26권4호
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• pp.487-498
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• 2009

지난 2005년 1월 4일 보현산 천문대(BOAO)의 BOES(BOao Echelle Spectograph)를 이용하여 Machholz(C/2004Q2) 혜성을 관측하였다. 이 논문에서는 Machholz 혜성의 고분산 분광 자료를 이용하여 미확인 분광선에 관한 연구를 수행하였으며 연구에 이용된 분광선의 파장 범위는 $4800{\sim}8100{\AA}$ 영역이다. 기존에 있던 Swift- Tuttle 혜성 Brorsen-Metcalf 혜성, Austin 혜성, 그리고 122P/de Vieo 혜성의 자료들과 비교분석을 하였다. 다수의 미확인 분광선에 대한 원인물질을 알아냈고, 이러한 자료들은 앞으로 혜성 연구에 있어서 유용한 자료로 활용될 수 있을 것이다.