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The rocket ultraviolet spectrum of the planetary nebula NGC 7027An ultraviolet spectrum of NGC 7027 was obtained with a rocket-borne telescope. The observed fluxes are given on an absolute basis and upper limits are given for the strongest predicted lines which were not observed. The extinction correction was made on the basis of the observed and calculated line ratios for the hydrogenic recombination line of He 2 at 1640A to H beta. The extinction is in agreement with ground based determinations. When corrected for extinction the C 4 resonance line at 1549A is in good agreement with the intensity calculated from models, but the C 3 intercombination line at 1909A is a factor of ten too bright. The addition of dielectronic recombination to the models sufficiently changes the C 3 concentration to reduce the discrepancy to a factor of four. The abundance of carbon is assumed to be 2 x 0.0001 that of hydrogen. Using carbon abundances for the sun, this discrepancy disappears and there must be attenuation in the C 4 line. Since the optical depth is approximately 10,000 at the line center, no appreciable number of absorbing grains can exist in the C 4 producing region of the nebula.
Document ID
19750016522
Acquisition Source
Legacy CDMS
Document Type
Preprint (Draft being sent to journal)
Authors
Bohlin, R. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Marionni, P. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Stecher, T. P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 3, 2013
Publication Date
May 1, 1975
Subject Category
Astronomy
Report/Patent Number
NASA-TM-X-70892
X-672-75-113
Accession Number
75N24594
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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