  Axion-Like Particles (ALPs) coupled with electrons would be produced in a
Supernova (SN) via electron-proton bremsstrahlung and electron-positron fusion.
We evaluate the ALP emissivity from these processes by taking into account the
ALP mass and thermal effects on electrons in the strongly degenerate and
relativistic SN plasma. Using a state-of-the-art SN simulation, we evaluate the
SN 1987A cooling bound on ALPs for masses in the range $1-200$ MeV, which
excludes currently unprobed regions down to $g_{ae}\sim 2.5\times 10^{-10}$ at
$m_a\sim 120$ MeV.
