• Title/Summary/Keyword: ultraviolet astronomical observations

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Far Ultraviolet Observations of the ${\zeta}$ Ophiuchi HII region

  • Choi, Yeon-Ju;Min, Kyoung-Wook;Seon, Kwang-Il
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.60.1-60.1
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    • 2014
  • The star ${\zeta}$ Ophiuchi (HD 149757) is one of the brightest massive stars in the northern hemisphere and was widely studied in various wavelength domains. We report the analysis results of far ultraviolet (FUV) observations with other wavelengths for around ${\zeta}$ Ophiuchi. We study the correlation of between multi wavelength observations. We have developed a Monte Carlo code that simulates dust scattering of light including multiple encounters. The code is applied to the present Oph HII region to obtain the geometrical information of dust such as distance and thickness. Also We apply three-dimensional photoionization code to model Wisconsin $H{\alpha}$ Mapper observations of the H II region surrounding the star.

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Far-ultraviolet Observations of the Comet C/2001 Q4 (NEAT)

  • Im, Yeo-Myeong;Min, Gyeong-Uk
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.91.2-91.2
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    • 2010
  • We present far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS, also called SPEAR) around perihelion between 8 and 15 May 2004. Several important emission lines, including S I (1425, 1474 ${\AA}$), C I (1561, 1657 ${\AA}$), CO (1087.9, 1340-1680 ${\AA}$) were detected. Especially, the spectral features of CO are its electronic transitions belongings to the A-X, C-X systems. We also obtained radial profile of S I, C I, H I $Ly{\beta}$ with line fitting from central coma. The production rate of several spectral lines calculated from observed FUV photon flux. FUV spectral images of S I, C I, H I $Ly{\beta}$ emission lines were obtained.

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FUV IMAGING SPECTROSCOPIC OBSERVATIONS OF INTERSTELLAR MEDIUM WITH FIMS

  • SEON KWANG-IL;HAN WONYONG;LEE DAE-HEE;NAM UK-WON;PARK JANG-HYUN;YUK IN-SOO;JIN HO;MIN KYUNG WOOK;RYU KWANG-SUN;EDELSTEIN JERRY;KORPELA ERIC
    • Journal of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.69-72
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    • 2005
  • The FIMS (Far-ultraviolet IMaging Spectrograph; also known as SPEAR, Spectroscopy of Plasma Evolution from Astrophysical Radiation) is the primary payload of the STSAT-1, the first Korean science satellite, which was launched in September, 2003. The FIMS performs spectral imaging of diffuse far-ultraviolet emission with the unprecedented wide field of view and the relatively good spectral resolution. We present far-ultraviolet spectral observations of highly ionized interstellar medium including supernova remnants, superbubbles, soft X-ray shadows, and the molecular hydrogen fluorescent emission lines. The FIMS has detected He II, C III, 0 III, O IV, Si IV, O VI, and $H_2$ fluorescent emission lines. The emission lines arise in shocked or thermally heated and in photo-ionized gases. We present an overview of the FIMS instrument and its initial observational results.

THE STUDY OF OB STELLAR ASSOCIATIONS WITH THE GLAZAR

  • TOVMASSIAN H. M.;HOVHANNESSIAN R. KH.;EPREMIAN R. A.;HUGUENIN D.;NAVARRO S. G.
    • Journal of The Korean Astronomical Society
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    • v.29 no.spc1
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    • pp.149-150
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    • 1996
  • The results of observations of a dozen OB stellar associations made with the ultraviolet space telescope Glazar is presented.

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ORFEUS OBSERVATIONS OF ULTRAVIOLET EXCITED HIGH-J MOLECULAR HYDROGEN

  • Lee, Dae-Hee;Dixon, W. Van Dyke;Min, Kyoung-Wook;Pak, Soo-Jong
    • Journal of The Korean Astronomical Society
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    • v.42 no.6
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    • pp.145-153
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    • 2009
  • We present measurements of diffuse interstellar $H_2$ absorption lines in the continuum spectra of 10 early-type stars. The data were observed with the Berkeley Extreme and Far-Ultraviolet Spectrometer (BEFS) of the ORFEUS telescope on board the ORFEUS-SPAS I and II space-shuttle missions in 1993 and 1996, respectively. The spectra extend from the interstellar cutoff at 912 $\AA$ to about 1200 $\AA$ with a resolution of ~ 3000 and statistical signal-to-noise ratios between 10 and 65. Adopting Doppler broadening velocities from high-resolution optical observations, we obtain the $H_2$ column densities of rotational levels J" = 0 through 5 for each line of sight. The kinetic temperatures derived from J" = 0 and 1 states show a small variation around the mean value of 80 K, except for the component toward HD 219188, which has a temperature of 211 K. Based on a synthetic interstellar cloud model described in our previous work, we derive the incident UV intensity IUV and the hydrogen density $n_H$ of the observed components to be -0.4 $\leq$ log $I_{UV}\leq2.2$ and $6.3{\leq}n_H2500cm^{-3}$, respectively.

Bright stars observed by FIMS/SPEAR

  • Jo, Young-Soo;Seon, Kwang-Il;Min, Kyoung-Wook;Choi, Yeon-Ju;Lim, Tae-Ho;Lim, Yeo-Myeong;Edelstein, Jerry;Han, Wonyong
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.44.1-44.1
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    • 2016
  • In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of $2-3{\AA}$ over the wavelength of $1370-1710{\AA}$. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

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