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The Ionization Structure of NGC 6720 and NGC 7009

Published online by Cambridge University Press:  18 September 2017

T. Barker*
Affiliation:
Wheaton College, Norton, Massachusetts, USA

Extract

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Measurements of line intensities over a spectral range generally as great as 1300 Å to 11,000 Å have been made in four positions in the Ring Nebula and eight positions in NGC 7009. Ionic abudances determined from optical and UV lines are in good agreement, except that the C2+ abundance inferred from the optical 4267 Å recombination line is as much as 10 times higher than that measured from the 1906, 1909 Å CIII) lines. In both nebulae, this discrepancy is greatest nearest the central star. At the present time the most attractive explanation seems to be that the 4267 Å line is affected by resonance fluorescence due to light from central stars of planetaries.

Type
Abstracts of Contributed Papers
Copyright
Copyright © Reidel 1983