B. Espey
Center for Astrophysical Sciences,
Department of Physics and Astronomy,
The Johns Hopkins University, Baltimore MD 21218;
espey@pha.jhu.edu
F. P. Keenan and F. C. McKenna
Department of Pure and Applied Physics,
The Queen's University of Belfast, Belfast BT7 1NN, Northern Ireland, UK;
f.keenan@qub.ac.uk; f.mckenna@qub.ac.uk
W. A. Feibelman
Laboratory for Astronomy and Solar Physics,
Code 684.1, NASA--Goddard Space Flight Center, Greenbelt MD 20771;
feibelman@iue.gsfc.nasa.gov
and
K. M. Aggarwal
Department of Physics and Astrophysics,
University of Delhi, Delhi 110 007, India
(1006.1 Å)/I(999.6 Å) and
(1010.6 Å)/I(999.6 Å). Temperature-sensitive ratios are also given
for the Ne V] ratio R = I(1137.0 Å)/I(1574.8 Å).
We discuss the potential usefulness of these line ratios for studying hot gas and apply
them to the case of the symbiotic system RR Tel.
Using far-UV data that has recently been acquired with the Hopkins Ultraviolet Telescope, we
conclude that the Ne V and Ne VI emission in RR Tel is due to photoionization, with the
temperature and density of the emitting region being
approximately 
18,000 K and 
10
cm
,
respectively. These results are similar to those estimated using other high ionization
line diagnostics of the
nebular material, such as O V I(1371 Å)/I(1644 Å) and Ne IV I(1602 Å)/I(2423 Å).
Although these Ne V and Ne VI lines have been used as diagnostics for solar physics,
we believe that this is the first instance in which they have been applied to another
astrophysical object.
Subject headings: atomic data -- atomic processes -- binaries: symbiotic -- stars: individual (RR Tel) -- ultraviolet: stars