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Nonequilibrium iron oxide formation in some low-mass post-asymptotic giant branch starsUsing experimental evidence that under highly oxidizing conditions gamma-Fe2O3 (maghemite) and Fe3O4 display refractory behavior, it is proposed that very low C/O ratios, that could be unique to evolving AGB stars, induce nonequilibrium formation of ferromagnetic iron oxide grains along with chondritic dust. The oxides are preferentially fractionated from chondritic dust in the stellar magnetic field which could account for the observed extreme iron underabundance in their photosphere. A search for the 1-2.5-micron IR absorption feature, or for diagnostic magnetite and maghemite IR absorption features, could show the validity of the model proposed.
Document ID
19930032150
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rietmeijer, Frans J. M. (New Mexico Univ. Albuquerque, United States)
Date Acquired
August 15, 2013
Publication Date
November 20, 1992
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 400
Issue: 1
ISSN: 0004-637X
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAG9-160
Distribution Limits
Public
Copyright
Other