ABUNDANCES OF GALACTIC ANTICENTER PLANETARY NEBULAE AND THE OXYGEN ABUNDANCE GRADIENT IN THE GALACTIC DISK

Journal Article · Sat Nov 20 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/724/1/748· OSTI ID:21471163

Henry, R B. C.; Morrison, Michael A ^[1]; Kwitter, Karen B; Jaskot, Anne E ^[2]; Balick, Bruce ^[3]

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1. H. L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)
2. Department of Astronomy, Williams College, Williamstown, MA 01267 (United States)
3. Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)

We have obtained spectrophotometric observations of 41 anticenter planetary nebulae (PNe) located in the disk of the Milky Way. Electron temperatures and densities, as well as chemical abundances for He, N, O, Ne, S, Cl, and Ar were determined. Incorporating these results into our existing database of PN abundances yielded a sample of 124 well-observed objects with homogeneously determined abundances extending from 0.9 to 21 kpc in galactocentric distance. We performed a detailed regression analysis which accounted for uncertainties in both oxygen abundances and radial distances in order to establish the metallicity gradient across the disk to be 12 + log(O/H) = (9.09 {+-} 0.05) - (0.058 {+-} 0.006) x R{sub g} , with R{sub g} in kpc. While we see some evidence that the gradient steepens at large galactocentric distances, more objects toward the anticenter need to be observed in order to confidently establish the true form of the metallicity gradient. We find no compelling evidence that the gradient differs between Peimbert Types I and II, nor is oxygen abundance related to the vertical distance from the galactic plane. Our gradient agrees well with analogous results for H II regions but is steeper than the one recently published by Stanghellini and Haywood over a similar range in galactocentric distance. A second analysis using PN distances from a different source implied a flatter gradient, and we suggest that we have reached a confusion limit which can only be resolved with greatly improved distance measurements and an understanding of the natural scatter in oxygen abundances.

• OSTI ID: 21471163
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 724; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ELECTRON TEMPERATURE
ELEMENTS
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
MATHEMATICS
MILKY WAY
NEBULAE
NONMETALS
OXYGEN
PLANETARY NEBULAE
REGRESSION ANALYSIS
SPECTROPHOTOMETRY
STATISTICS