A&A 423, 199-207 (2004)
Chemical abundances of planetary nebulae towards the Galactic anticenterR. D. D. Costa, M. M. M. Uchida and W. J. Maciel
Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG), Universidade de São Paulo, Rua do Matão 1226, 05508-900, São Paulo SP, Brazil
(Received 20 October 2003 / Accepted 24 April 2004 )
In this paper we report new observations and derive chemical abundances for a sample of 26 planetary nebulae (PN) located in the anticenter direction. Most of these nebulae are far away objects, located at Galactocentric distances greater than about 8 kpc, so that they are particularly useful for the determination of the radial gradients at large distances from the galactic center. A comparison of the present results with previously determined abundances suggests that the radial abundance gradients flatten out at distances larger than about 10 kpc from the center.
Key words: ISM: planetary nebulae: general -- Galaxy: disk -- ISM: abundances
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