The Opacity Project

The Opacity Project (OP) refers to an international collaboration that was formed in 1984 to calculate the extensive atomic data required to estimate stellar envelope opacities and to compute Rosseland-mean opacities and other related quantities. It has involved research groups from France, Germany, the United Kingdom, the United States and Venezuela. The state- of-the-art atomic calculations were carried out in the close coupling approximation using the R-matrix method. The OP team has published a comprehensive description in the book "The Opacity Project" (Vol.1, Institute of Physics Publishing, London UK, 1995), containing original papers and an extensive set of oscillator strengths.


TOPbase - Telnet and WWW Access

TOPbase is a read-only database system specially designed for general use of the OP atomic data. It contains energy levels, f-values and photoionization cross sections for astrophysically abundant elements.

TOPbase version has been specifically developed for interactive use of the data, and allows the ftp of selected data files. It contains data for ions with the following atomic and electron numbers:

**** TOPbase -- WWW interface at NASA GSFC (U.S. Site) ****

Telnet ( - login: topbase, password: Seaton+

Another link to TOPbase at CDS in Strasbourg, France is available via Opacity Project .

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Revised: 1995 Nov 7