The ISO-SWS Flux Standard Stars: Synthetic Spectra and Observations

Abstract

We present flux-calibrated, synthetic spectra for the calibration stars of the Short Wavelength Spectrometer of the Infrared Space Observatory ISOSWS (cf. Kessler et al. 1996). ISO-SWS covers a wavelength range of 2.4 to 45µm (cf. de Graauw et al. 1996), and although in the NIR the flux calibration of Vega can be used, at longer wavelengths the flux calibration has to be extrapolated by other means, because (i) Vega has at λ ≥ 25μm an IR excess due to circumstellar dust and (ii) there is an, as yet, unresolved controversy about Vega’s flux at 10µm (cf. Rieke et al. 1985). The majority of the standard stars of SWS are of MK class G and K III, as cool giants are amongst the brightest objects in the IR, and model atmospheres for cool giants are available and well-studied (cf. Jørgensen and Gustafsson 1994).