Predicted UV–optical emission spectra of photoionized asteroid material irradiated by ionizing continuum with ϕ = 2 × 10¹⁵ photons s⁻¹ cm⁻². The four panels correspond to different combinations of gas density, n_H = 10⁶ (upper two panels) or 10⁷ cm⁻³ (bottom) and total hydrogen column density, N_H = 10¹⁸ (left) and 10¹⁹ cm⁻² (right). Prominent emission lines are indicated by vertical dashed lines. We adopt a metallicity of Z = 100 Z_⊙ and a covering factor of 5%. These spectra illustrate how the emission-line strengths vary with gas density and column depth in the evaporating asteroidal clouds.