Morehead State University

Poster Title

Raman-Scattered He II at 6545 Å in Symbiotic Star and Planetary Nebulae

Institution

Morehead State University

Abstract

Many old stars are associated with gaseous nebulae. These nebulae are the results of mass loss from the star, via winds and ejection events, as the stars evolve. Nebulae produce emission lines that can be used to determine both the composition and dynamics of the gas. We report the detection of weak emission lines at approximately 6545 Å due to Raman scattering of He II in several symbiotic stars and planetary nebulae. Raman scattering is non-elastic scattering of He II photons in the ground state of neutral hydrogen. Van Groningen first identified Raman scattering of He II as weak emission features at about 4332 Å and 4851 Å. He identified the above lines as resulting from the inelastic scattering of far-ultraviolet 949 Å and 972 Å photons on the ground state of neutral hydrogen. Raman scattering of He II lines at about 6545 Å have been identified more recently in the spectrum of RR Tel, He 2-106, and V1016 Cyg symbiotic stars and the planetary nebulae M2-9. We will discuss the implications of the identification of Raman scattered He II of HM Sge and NGC 7027.

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Raman-Scattered He II at 6545 Å in Symbiotic Star and Planetary Nebulae

Many old stars are associated with gaseous nebulae. These nebulae are the results of mass loss from the star, via winds and ejection events, as the stars evolve. Nebulae produce emission lines that can be used to determine both the composition and dynamics of the gas. We report the detection of weak emission lines at approximately 6545 Å due to Raman scattering of He II in several symbiotic stars and planetary nebulae. Raman scattering is non-elastic scattering of He II photons in the ground state of neutral hydrogen. Van Groningen first identified Raman scattering of He II as weak emission features at about 4332 Å and 4851 Å. He identified the above lines as resulting from the inelastic scattering of far-ultraviolet 949 Å and 972 Å photons on the ground state of neutral hydrogen. Raman scattering of He II lines at about 6545 Å have been identified more recently in the spectrum of RR Tel, He 2-106, and V1016 Cyg symbiotic stars and the planetary nebulae M2-9. We will discuss the implications of the identification of Raman scattered He II of HM Sge and NGC 7027.