Effects of dust formation on chemical abundancesGas-phase abundances of C, Mg, Si, Ca, and Fe have been measured for a number of planetary nebulae on the basis of optical, ultraviolet, and infrared emission-line intensities. The abundances of Si, Ca, and Fe show characteristic depletions of one to two orders-of-magnitude as a result of grain formation. Magnesium shows a similar depletion in the outer parts of several planetary nebulae, but it is undepleted in their inner parts. Carbon is not detectably depleted by grain formation. Efficient condensation of refractory elements can easily occur during the early stages of formation of a planetary nebula; but the observed, residual gas-phase abundances are not understood. Observations of molecules in the envelopes of late-type stars may provide useful clues.
Document ID
19830067927
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Shields, G. A. (Texas, University Austin, TX, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1983
Subject Category
Astrophysics
Meeting Information
Meeting: Planetary nebulae; Proceedings of the Symposium