• Title/Summary/Keyword: symbiotic stars

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High Resolution Spectroscopy of Raman Features in Symbiotic Stars and Young Planetary Nebulae Using the BOES

  • Lee, Hee-Won
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.59.4-60
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    • 2016

  • One important aspect of the late stage stellar evolution is the mass loss processes, where a significant amount of stellar material will be returned to the interstellar space to be used for stars of the next generation. Raman scattered O VI and He II by atomic hydrogen in symbiotic stars and young planetary nebulae are found to be excellent tools to investigate the mass loss processes and estimate the mass loss rate. These features appear near hydrogen Balmer emission lines due to the huge cross section in the vicinity of Lyman resonance transitions. With the capability of high spectral resolution and broad spectral coverage, BOES is an ideal instrument to perform Raman spectroscopy of these objects. In this talk, a cursory overview of our research activities on Raman spectroscopy of symbiotics and PNe using the BOES is presented.

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STRENGTH OF THE RAMAN SCATTERED HE II EMISSION LINES IN SYMBIOTIC STARS AND PLANETARY NEBULAE

  • LEE HEE-WON
    • 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$\alpha$.

  • https://doi.org/10.5303/JKAS.2003.36.2.055 인용 PDF KSCI

THE FORMATION OF THE DOUBLE GAUSSIAN LINE PROFILES OF THE SYMBIOTIC STAR AG PEGASI

  • Hyung, Siek;Lee, Seong-Jae
    • Journal of The Korean Astronomical Society
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    • v.53 no.2
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    • pp.35-42
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    • 2020

  • We analyze high dispersion emission lines of the symbiotic nova AG Pegasi, observed in 1998, 2001, and 2002. The Hα and Hβ lines show three components, two narrow and one underlying broad line components, but most other lines, such as HI, HeI, and HeII lines, show two blue- and red-shifted components only. A recent study by Lee & Hyung (2018) suggested that the double Gaussian lines emitted from a bipolar conical shell are likely to form Raman scattering lines observed in 1998. In this study, we show that the bipolar cone with an opening angle of 74°, which expands at a velocity of 70 km s-1 along the polar axis of the white dwarf, can accommodate the observed double line profiles in 1998, 2001, and 2002. We conclude that the emission zone of the bipolar conical shell, which formed along the bipolar axis of the white dwarf due to the collimation by the accretion disk, is responsible for the double Gaussian profiles.

  • https://doi.org/10.5303/JKAS.2020.53.2.35 인용 PDF KSCI