Emergent energy spectra (top panel) and temperature structures (bottom panel) of four low luminosity (ℓ = 0.001) helium model atmospheres heated by α-particles with luminosity ℓ_a = 0.05 and parameters η = 0.25 and Ψ = 60°. The presented models have different temperature parameter χ = 0.1, 0.2, 0.5, and 0.7. The fit to the spectrum above 5 keV with an exponential cutoff power law with Γ = 2.15, E_cut = 85 keV is shown for χ = 0.1. The dotted curve shows the blackbody with temperature kT = 1 keV.