Chemical Abundances from Planetary Nebulae in the Magellanic Clouds

Abstract

AbstractHeavy element abundances, in particular those of oxygen, obtained from recent spectroscopic surveys of Magellanic Cloud planetary nebulae (PN), are reviewed and compared with those derived for H regions and objects in our own galaxy. These abundances have been based on collisionally excited lines and are very sensitive to the adopted electron temperature. There is increasing evidence that temperature or density fluctuations within nebulae lead to the electron temperatures being overestimated, with the corollary that the heavy element abundances have been underestimated.