W. J. Maciel - Abstract #40STRONGLY METAL DEFICIENT PLANETARY NEBULAEW. J. Maciel, J. A. Freitas Pacheco, S. J. Codina-Landaberry Rev. Mexicana Astron. Astrofis. 21, 517-520 (1990) We study a group of planetary nebulae of type II with extremely low abundances of heavy elements. It is concluded that their central stars have masses lower than expected from most stellar evolution calculations. |