The Opacity Project Tables Service

For historical reasons, stellar structure codes have been using the opacity tables from OPAL. However, after the first release of its opacities in 1995 [1] dedicated to stellar envelope conditions, The Opacity Project (OP) [2] pursued the work of atomic calculations and extended the different databases (TipTopbase). Finally the OP released in 2004 [3] the new set of monochromatic opacities available on the present site under Opacity Project (OPCD3.3). In order to simplify the work of stellar modellers, we now provided this service to generate opacity tables for any composition fully compatible with the OPAL routine.

1 - The Opacity Project Team, 1995, The Opacity Project Vol. 1, Institute of Physics Publications, Bristol, UK
2 - Seaton M.J., 1987, J. Phys. B 20, 6363. Abstract
3 - Badnel et al., 2005, MNRAS, Volume 360, Issue 2, pp. 458-464. Abstract
4 - Grevesse, N.; Sauval, A. J.; Space Science Reviews, v. 85, Issue 1/2, p. 161-174 (1998) Abstract

To generate an opacity tables in the type1 OPAL format, insert your e-mail address, modify the Fractions related to each metal; and press on 'Compute' button. You will receive your results by e-mail.

You can also preview and download the existing results
or use our Standalone Client (for processing multiple compositions at once)

Number Fraction
Log Scale

    E-mail address    




H 12 12
He 10.93 10.93
C 8.52
N 7.92
O 8.83
Ne 8.08
Na 6.33
Mg 7.58
Al 6.49
Si 7.56
P 5.56
S 7.20
Cl 5.28
Ar 6.40
K 5.13
Ca 6.35
Ti 4.94
Cr 5.69
Mn 5.53
Fe 7.50
Ni 6.25

Note: All the solar mixtures (GS98, Asplund2xxx, Caffau2009, Lodders2009) are based upon a 21 elements mixture like OPAL. However, when the table are generated, it reduces the composition to the 17 elements present in The Opacity Project database. The contribution of each of the 4 missing elements is transfered to the closest element above it in the periodic table as explained in Delahaye & Pinsonneault 2006 Abstract.

For more informations about this service or in case of troubleshooting please contact Frank Delahaye or Carlo Maria Zwölf

CNRS OSU Auburn Université de Cergy Pontoise ias ville de Paris Observatoire de Paris
CNES bruker ville de Paris cea Cambridge