  Stellar energy loss arguments lead to strong constraints on the coupling
$\phi \gamma \gamma$ of a light axion-like particle to two photons.
Helioscopes, like CAST, are able to put competitive bounds. The PVLAS
experiment has recently observed a rotation of the polarization of a laser
propagating in a magnetic field that can be interpreted as the effect of a
quite strong $\phi \gamma \gamma$ coupling. We present scenarios where the
astrophysical and CAST bounds can be evaded, and we show that the PVLAS result
can be accomodated in one of the models, provided the new physics scale is at
very low energies.
