AAS 205th Meeting, 9-13 January 2005
Session 52 Stellar Atmospheres, Abundances and Opacities
Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall

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[52.14] Up-dated Opacities from the Opacity Project.

N. R. Badnell (University of Strathclyde, UK), M. J. Seaton (UCL, UK), M. A. Bautista (IVIC, Venezuala), K. Butler (University of Munich, Germany), F. Delahaye (Ohio State University), C. Mendoza (IVIC, Venezuala), P. Palmeri (GSFC), C. J. Zeippen (Meudon, France)

Using the code AUTOSTRUCTURE, extensive calculations of inner-shell atomic data have been made for the chemical elements He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. The results are used to obtain up-dated opacities from the Opacity Project, OP. A number of other improvements on earlier work have also been included.

Rosseland-mean opacities from OP are compared with those from OPAL. Differences of 5 to 10% occur. OP gives the `Z-bump', at \log(T)~5.2, to be shifted to slightly higher temperatures. The opacities from OP, as functions of temperature and density, are smoother than those from OPAL. Extensive tests show that the numerical accuracy of the OP opacities following integration over frequency mesh and interpolation on temperature--density mesh is better than 1%.

Prior to a number of recent investigations which have indicated a need for a downward revision in the solar abundances of oxygen and other elements, there was good agreement between properties of the sun deduced from helioseismology and from stellar evolution models calculated using OPAL opacities. The revisions in abundances destroy that agreement. Results from up-dated OP opacities will be presented for the region of the solar radiative interior.

The author(s) of this abstract have provided an email address for comments about the abstract: badnell@phys.strath.ac.uk

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© 2004. The American Astronomical Society.