Helioseismological constraint on solar axion emission
  Helioseismological sound-speed profiles severely constrain possible deviations from standard solar models, allowing us to derive new limits on anomalous solar energy losses by the Primakoff emission of axions. For an axion-photon coupling $g_{a\gamma} < 5 x 10^(-10) GeV^(-1)$ the solar model is almost indistinguishable from the standard case, while $g_{a\gamma} > 10 x 10^(-10) GeV^(-1)$ is probably excluded, corresponding to an axion luminosity of about $0.20 L_(sun)$. This constraint on $g_{a\gamma}$ is much weaker than the well-known globular-cluster limit, but about a factor of 3 more restrictive than previous solar limits. Our result is primarily of interest to the large number of current or proposed search experiments for solar axions because our limit defines the maximum g_{a\gamma}$ for which it is self-consistent to use a standard solar model to calculate the axion luminosity. 
Helmut Schlattl, Achim Weiss (MPA Garching), Georg Raffelt (MPP   Muenchen)