NAM logo, by David Le Conte

The effect of FeI opacity on the solar ultraviolet flux

R.A. Bell (University of Maryland)

Balachandran & Bell (Nature 392, 791, 1998) found that it was necessary to increase the continuous opacity in the solar atmosphere at a wavelength of 3100 Angstroms over its standard value if the solar oxygen abundance derived from lines of the OH A-X system was to match that derived from the vibration - rotation lines of OH. Such an increase in continuous opacity causes the photospheric abundance of beryllium to match the meteoritic abundance to within the error limits. The increase also reduces the solar ultraviolet flux.

Balachandran & Bell suggested that an opacity increase could be produced by correcting for an underestimate of the FeI continuous opacity. Repeating the calculations using the more recent Opacity Project FeI calculations of Bautista (A&AS, 122,167,1997) shows a substantial alteration in the solar ultraviolet flux, particularly shortward of 3000 Angstroms. An increase of a factor of two in Bautista's values gives continuous fluxes which, when combined with the observed solar line blocking, gives very good agreement with solar fluxes observed by the Solstice experiment (Woods et al. JGR, D6, 9541, 1996).

This work was done in collaboration with Drs S. Balachandran and M Bautista.

Maintained by Ian Howarth