POSTER PAPER 3.10
Metallicity and Infrared Debris Disks: ISO Evidence for Anti-correlation
M.L. Edwards and R.E. Stencel
Institute: University of Denver, Department of Physics and Astronomy, www.du.edu
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Abstract:
University of Denver (DU) executed a NASA key project that acquired a magnitude limited sample of 66 stars from the Infrared Space Observatory (ISO) mission, looking for infrared signatures indicative of planet formation around nearby stars. Age and abundance data has been obtained from the literature to supplement the infrared photometry performed by the ISO satellite in the interest of discovering correlations between infrared excesses, ages, and chemical abundances. There are two possible scenarios other than the null possibility where disk stars are identical chemically to non-disk stars. Either the disk will enhance the metal content of the star through accretion or it will lower the metalicity of the parent star by acting as a sink for iron and other heavy elements. The most likely scenario is that young stars with disks will show evidence of a low abundance pattern as the heavy elements in the protostellar cloud form regions of higher density, thus making their own regions of gravitational collapse independent of the main stellar mass. Then as these planetesimals collapse into the parent star the abundances return to more normal levels as time passes, perhaps even increasing the abundances to unusually high levels. The strongest conclusion from the University of Denver ISO sample is that infrared excesses decrease slowly over time regardless of sample choice. This means that dust disks are persistent features of a star, so persistent that a mechanism for replenishing the dust is necessary in order to explain the strength of dust found around older stars.
Index Keywords: Infrared Excess; Metallicity; ISO
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Manuscript submitted: 2001-Sep-06
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.