6 research outputs found
Contemporaneous Observations of Direct and Raman Scattered O VI in Symbiotic Stars
Symbiotic stars are binary systems consisting of a hot star, typically a
white dwarf, and a cool giant companion. The wind from the cool star is ionized
by the radiation from the hot star, resulting in the characteristic combination
of sharp nebular emission lines and stellar molecular absorption lines in the
optical spectrum. Most of the emission lines are readily identifiable with
common ions. However, two strong, broad emission lines at
6825, 7082 defied identification with known atoms and ions. In 1989 Schmid made
the case that these long unidentified emission lines resulted from the Raman
scattering of the O VI resonance photons at 1032, 1038 by
neutral hydrogen.
We present contemporaneous far-UV and optical observations of direct and
Raman scattered O VI lines for nine symbiotic stars obtained with the Hopkins
Ultraviolet Telescope (Astro-2) and various ground-based telescopes. The O VI
emission lines are present in every instance in which the
6825, 7082 lines are present in support of the Schmid Raman scattering model.
We calculate scattering efficiencies and interpret the results in terms of the
Raman models. Additionally, we measure the flux of the Fe II fluorescence line
at 1776, which is excited by the O VI line at 1032, and
calculate the first estimates of the conversion efficiencies of this process.Comment: 48 pages, 5 figure