A comparison between observed and calculated IRAS fluxes of G and K giant stars

Infrared fluxes are calculated for a grid of cool $$(5500 \ge T_{eff} \ge 4000 K)$$ model stellar atmospheres and for models of Sirius and Vega. These fluxes are convolved with the response functions of the IRAS satellite to yield data that can be compared with observational data. Using stellar angular diameters derived by Bell & Gustafsson, the agreement between observed and calculated fluxes is good, the mean ratios of observed to calculated fluxes for a sample of 20 cool stars being 0.985, 1.033, 0.927 and 0.95 for the 12-, 25-, 60- and 100-μm passbands using one calibration approach, and 0.988, 1.012, 0.988 and 0.99 using the IRAS Supplement procedure. Intrinsic fluxes are given for 15 of these stars. Observed and computed fluxes are also compared for Sirius and Vega. The differences between the fluxes convolved with the detector responses, the monochromatic fluxes at the detector effective wavelengths, and the fluxes found using the ‘in-band’ observations are given, and some details of the properties of the models relevant to the flux calculations are described.