  Stellar evolution considerations are of fundamental importance in our
understanding of the axion/ALP-photon coupling, g_{a\gamma}. Helium burning
stars are the best laboratories to study this coupling. Here, we will review
the bounds from massive and low mass helium burning stars, and present a new
analysis of the bound from the horizontal branch stars. The analysis provides
the strongest bound to date on g_{a\gamma} in a wide mass range.
