Nature: Iron opacity of the Sun higher than predicted
Posted: Wed Dec 31, 2014 12:55 pm
I thought I'd post this here, rather on a new thread, although it's only tangentially related. But it interested me.
M
Although the actual letter is behind a £22 paywall, the authors' abstract at this link is both informative and concise.Nature letters: A higher-than-predicted measurement of iron opacity at solar interior temperatures
J. E. Bailey, T. Nagayama et al
Nature 517, 56–59 (01 January 2015) doi:10.1038/nature14048
Received 17 September 2014 Accepted 03 November 2014 Published online 31 December 2014
Editor's summary
Internal temperature profiles of the Sun and other stars are controlled in large part by the rate at which radiation is absorbed by stellar matter. Until now it has not been possible to determine the opacity of matter in star-like conditions in the laboratory, but James Bailey et al. have now achieved that feat using the Sandia National Laboratories' Z facility, the world's most powerful X-ray generator. The experiments reveal a wavelength-resolved iron opacity that is 30 to 400 times greater than predicted in conditions very similar to those at the radiation/convection zone boundary in the Sun. Previous measurements of stellar interiors have been based on observations of surface waves, and there were serious discrepancies between theoretical predictions and observations. The new measurements account for about half of adjustment in opacity figures required to restore agreement between standard solar models and observations.
M