METAL-POOR PLANETARY NEBULAE: EFFECTS OF WINDS
W. J. Maciel
Astrophys. Space Sci. 209, 65-70 (1993)
Some planetary nebulae in the galactic thick disk display extremely
low abundances of heavy elements such as O, Ne, S, and Ar, compared
with "normal" or type II nebulae. Their central stars are generally
relatively cool and underluminous, indicating that the progenitor stars
had very low masses. It is suggested that strong stellar winds have
had an important role in the formation of these objects, which is
supported by the large mass loss rates now observed.
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