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Title: Condensation of refractory metals in asymptotic giant branch and other stellar environments

Abstract

The condensation of material from a gas of solar composition has been extensively studied, but less so condensation in the environment of evolved stars, which has been mainly restricted to major compounds and some specific element groups such as the Rare Earth elements. Also of interest, however, are refractory metals like Mo, Ru, Os, W, Ir, and Pt, which may condense to form refractory metal nuggets (RMNs) like the ones that have been found in association with presolar graphite. We have performed calculations describing the condensation of these elements in the outflows of s-process enriched AGB stars as well as from gas enriched in r-process products. While in carbon-rich environments (C > O), the formation of carbides is expected to consume W, Mo, and V (Lodders and Fegley), the condensation sequence for the other refractory metals under these conditions does not significantly differ from the case of a cooling gas of solar composition. The composition in detail, however, is significantly different due to the completely different source composition. Condensation from an r-process enriched source differs less from the solar case. Elemental abundance ratios of the refractory metals can serve as a guide for finding candidate presolar grains among the RMNsmore » in primitive meteorites—most of which have a solar system origin—for confirmation by isotopic analysis. We apply our calculations to the case of the four RMNs found by Croat et al., which may very well be presolar.« less

Authors:
; ;
Publication Date:
OSTI Identifier:
22365044
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; ASYMPTOTIC SOLUTIONS; CARBIDES; COMPUTERIZED SIMULATION; ELEMENT ABUNDANCE; GIANT STARS; GRAPHITE; METEORITES; R PROCESS; RARE EARTHS; REFRACTORIES; REFRACTORY METALS; S PROCESS; SOLAR SYSTEM; SPACE; STAR EVOLUTION; STARS; SUPERNOVA REMNANTS

Citation Formats

Schwander, D., Berg, T., Schönhense, G., and Ott, U., E-mail: schwandd@uni-mainz.de. Condensation of refractory metals in asymptotic giant branch and other stellar environments. United States: N. p., 2014. Web. doi:10.1088/0004-637X/793/1/20.
Schwander, D., Berg, T., Schönhense, G., & Ott, U., E-mail: schwandd@uni-mainz.de. Condensation of refractory metals in asymptotic giant branch and other stellar environments. United States. https://doi.org/10.1088/0004-637X/793/1/20
Schwander, D., Berg, T., Schönhense, G., and Ott, U., E-mail: schwandd@uni-mainz.de. 2014. "Condensation of refractory metals in asymptotic giant branch and other stellar environments". United States. https://doi.org/10.1088/0004-637X/793/1/20.
@article{osti_22365044,
title = {Condensation of refractory metals in asymptotic giant branch and other stellar environments},
author = {Schwander, D. and Berg, T. and Schönhense, G. and Ott, U., E-mail: schwandd@uni-mainz.de},
abstractNote = {The condensation of material from a gas of solar composition has been extensively studied, but less so condensation in the environment of evolved stars, which has been mainly restricted to major compounds and some specific element groups such as the Rare Earth elements. Also of interest, however, are refractory metals like Mo, Ru, Os, W, Ir, and Pt, which may condense to form refractory metal nuggets (RMNs) like the ones that have been found in association with presolar graphite. We have performed calculations describing the condensation of these elements in the outflows of s-process enriched AGB stars as well as from gas enriched in r-process products. While in carbon-rich environments (C > O), the formation of carbides is expected to consume W, Mo, and V (Lodders and Fegley), the condensation sequence for the other refractory metals under these conditions does not significantly differ from the case of a cooling gas of solar composition. The composition in detail, however, is significantly different due to the completely different source composition. Condensation from an r-process enriched source differs less from the solar case. Elemental abundance ratios of the refractory metals can serve as a guide for finding candidate presolar grains among the RMNs in primitive meteorites—most of which have a solar system origin—for confirmation by isotopic analysis. We apply our calculations to the case of the four RMNs found by Croat et al., which may very well be presolar.},
doi = {10.1088/0004-637X/793/1/20},
url = {https://www.osti.gov/biblio/22365044}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 793,
place = {United States},
year = {Sat Sep 20 00:00:00 EDT 2014},
month = {Sat Sep 20 00:00:00 EDT 2014}
}