  We explore consequences of the idea that the cooling speed of white dwarfs
can be interpreted in terms of axion emission. In this case the Yukawa coupling
to electrons has to be g_{ae} 10^-13, corresponding to an axion mass of a few
meV. Axions then provide only a small fraction of the cosmic cold dark matter,
whereas core-collapse supernovae release a large fraction of their energy in
the form of axions. We estimate the diffuse supernova axion background (DSAB)
in the universe, consisting of 30 MeV-range axions with a radiation density
comparable to the extra-galactic background light. The DSAB would be
challenging to detect. However, axions with white-dwarf inspired parameters can
be accessible in a next generation axion helioscope.
