Emergent energy spectra (top panel) and temperature structures (bottom panel) for four low-luminosity (ℓ = 0.001) helium model atmospheres heated by α-particles with the accretion luminosity ℓ_a = 0.05 and parameters η = 0.75 and χ = 0.2. The models correspond to different incoming angles Ψ = 0°, 30°, 60°, and 85°. The emergent spectrum of the most inclined (Ψ = 85°) particle flow is well fitted at photon energies higher than 5 keV with an exponential cutoff power-law model with photon index Γ = 2.45 and cutoff energy E_cut = 85 keV (dashed curve). The blackbody spectrum of temperature kT = 1.1 keV is also shown by the dotted curve.