2003A&A...400..695D

Vega, Sirius, β Leo, α Car and α Cen A belong to a sample of twenty stellar sources used for the calibration of the detectors of the Short-Wavelength Spectrometer on board the Infrared Space Observatory (ISO-SWS). While general problems with the calibration and with the theoretical modelling of these stars are reported in Decin et al. (2003A&A...400..679D), each of these stars is discussed individually in this paper. As demonstrated in Decin et al. (2003A&A...400..679D), it is not possible to deduce the effective temperature, the gravity and the chemical composition from the ISO-SWS spectra of these stars. But since ISO-SWS is absolutely calibrated, the angular diameter (θ_d) of these stellar sources can be deduced from their ISO-SWS spectra, which consequently yields the stellar radius (R), the gravity-inferred mass (M_g) and the luminosity (L) for these stars. For Vega, we obtained θ_d=3.35±0.20mas, R=2.79±0.17R_☉, M_g=2.54±1.21M_☉ and L=61±9L_☉; for Sirius θ_d=6.17±0.38mas, R=1.75±0.11R_☉, M_g=2.22±1.06M_☉ and L=29±6L_☉; for β Leo θ_d=1.47±0.09mas, R=1.75±0.11R_☉, M_g=1.78±0.46M_☉ and L=15±2L_☉; for α Car θ_d=7.22±0.42mas, R=74.39±5.76R_☉, M_g=12.80^+24.95_–6.35M_☉ and L=14573±2268L_☉ and for α Cen A θ_d=8.80 ±0.51mas, R=1.27±0.08R_☉, M_g=1.35±0.22M_☉ and L=1.7±0.2L_☉. These deduced parameters are confronted with other published values and the goodness-of-fit between observed ISO-SWS data and the corresponding synthetic spectrum is discussed.