The emission and absorption spectra of Kr and Xe atoms near the P-1,3(1)-S-1(0) resonance lines in an atmosphere of helium atoms under equilibrium conditions have been theoretically investigated. Potential curves for excited states of Kr(4p(5)5s) + He and Xe(5p(5)6s) + He quasi-molecules are obtained with joint application of the effective Hamiltonian and pseudopotential methods. Experimental data are used for the ground state. Based on these potential curves, the spectral profiles of quasi-molecular emission and absorption for short-wavelength wings of the resonance lines are calculated within the quasi-static approximation. The results obtained for absorption are compared with the known experimental data.