Ionization structure of planetary nebulae. Part 8: NGC 6826

Technical Report · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6568980

Barker, T

Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 1700 A were made in seven positions in the planetary nebulae NCG 6826. The O(++) electron temperature varies little from 8900 K throughout the nebula; the Balmer continuum electron temperature averages 1500 K higher. The wavelength 4267 C II line intensities imply C(++) abundances that are systematically higher than those determined from the wavelength 1906, 1909 C III lines, but because of uncertainties in the intensities of the ultraviolet lines relative to the optical ones, this discrepancy is less conclusively demonstrated in NGC 6826 than in other planetaries in this series. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages give results that are consistent and also in approximate agreement with abundances calculated using ultraviolet lines in the few cases where the relevant ultraviolet lines are measurable. The results of the logarithmic abundances differ somewhat from the recent study by Aller and Czyzak, in part because their measured electron temperatures are somewhat higher. The Ar, Ne, and, to some extent, O and S abundances appear to be somewhat low, suggesting that the progenitor to NGC 6826 like that to NGC 7662, may have formed out of somewhat metal-poor material.

• Research Organization: Wheaton Coll., Norton, MA (USA)
• OSTI ID: 6568980
• Report Number(s): N-87-17581; NASA-CR-180142; NAS-1.26:180142
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ARGON
CARBON
CHEMICAL COMPOSITION
DATA
ELECTRON TEMPERATURE
ELEMENTS
EMISSION SPECTRA
EXPERIMENTAL DATA
FLUIDS
GASES
INFORMATION
IONIZATION
NEBULAE
NEON
NONMETALS
NUMERICAL DATA
OXYGEN
PLANETARY NEBULAE
RARE GASES
SPECTRA
SULFUR