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Astron. Astrophys. 345, 629-634 (1999)

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Abundance gradients in the outer galactic disk from planetary nebulae *

W.J. Maciel and C. Quireza

Instituto Astronômico e Geofísico, Universidade de São Paulo, Av. Miguel Stefano 4200, 04301-904 São Paulo SP, Brazil (maciel@iagusp.usp.br)

Received 1 December 1998 / Accepted 1 March 1999


Radial abundance gradients of the element ratios O/H, Ne/H, S/H, and Ar/H are determined on the basis of a sample of disk planetary nebulae. The behaviour of the gradients at large distances from the galactic centre, [FORMULA] kpc, is emphasized. It is concluded that the derived gradients are consistent with an approximately constant slope in the inner parts of the Galaxy, and some flattening for distances larger than [FORMULA]. A comparison is made with previous determinations using both photoionized nebulae and young stars, and some consequences on theoretical models for the chemical evolution of the galactic disk are discussed.

Key words: ISM: abundances – ISM: planetary nebulae: general – Galaxy: abundances

* Table 1 is available only electronically at the CDS (anonymous ftp or http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/345/629)

Send offprint requests to: W.J. Maciel

© European Southern Observatory (ESO) 1999

Online publication: April 19, 1999