Emergent (unredshifted) spectra and temperature structures of model atmospheres with two relative luminosities (l = 0.95 and 0.1) at fixed surface gravity (log g = 14.0) for various chemical compositions: pure hydrogen (dotted curves), pure helium (dashed curves) and solar mix of hydrogen and helium, and subsolar metal abundance Z = 0.3   Z_⊙ (solid curves). Top panel: spectra normalized to maximum flux versus photon energy in units of the effective temperature. Note, that T_eff ∝ l^1/4(1 + X)^−1/4. For clarity, the spectra for l = 0.95 are shifted along the ordinate axis by a factor of 10. Bottom panel: corresponding temperature structures (in units of the effective temperature) versus Thomson optical depth.