  The parameter space of massive axion-like-particles (ALPs) with $m_a \sim
{\mathcal O} (100)$ MeV and coupled with nucleons is largely unexplored. Here,
we present new constraints in this parameter region. In doing so, we
characterize the supernova emissivity of heavy ALPs from a proto-neutron star,
including for the first time mass effects in both nucleon-nucleon
Bremsstrahlung and pionic Compton processes. In addition, we highlight novel
possibilities to probe the couplings with photons and leptons from supernova
ALP decays.
