Betelgeuse spectrum as obtained from SPI for the 20–2000 keV energy range. The dot with the error bar shows the flux value in that energy bin. The downward-pointing arrows show the 3σ upper limit for bins where the flux significance is less than 2σ. The 511 keV bin is systematically large because of incomplete modeling of the diffuse emission in the Crab/Orion region and is therefore not taken as a detection of 511 keV in Betelgeuse. The red shaded region shows the flux from the g_aγ × g_ae values allowed by NuSTAR that can now directly be excluded from the ALP parameter space since the flux prediction from them is larger than the 3σ flux limits from SPI. The excluded limit is g_aγ × g_ae ≧ 3 × 10⁻²⁴ GeV⁻¹. The blue shaded region shows the flux from the g_aγ × g_ae values that were already disallowed in the NuSTAR study (Xiao et al. 2022).