Decin, L. ; Vandenbussche, B. ; Waelkens, K. ; Eriksson, C. ; Gustafsson, B. ; Plez, B. ; Sauval, A. J.

published in Astronomy and Astrophysics, 400, pp. 695-707 (2003)

Abstract: Vega, Sirius, beta Leo, alpha Car and alpha 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. (\cite{Decin2000b}), each of these stars is discussed individually in this paper. As demonstrated in {Decin} et al. (\cite{Decin2000b}), 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 (thetad ) of these stellar sources can be deduced from their ISO-SWS spectra, which consequently yields the stellar radius (R), the gravity-inferred mass (Mg) and the luminosity (L) for these stars. For Vega, we obtained thetad = 3.35 +/- 0.20 mas, R = 2.79 +/- 0.17 Rsun, Mg = 2.54 +/- 1.21 Msun and L = 61 +/- 9 Lsun; for Sirius thetad = 6.17 +/- 0.38 mas, R = 1.75 +/- 0.11 Rsun, Mg = 2.22 +/- 1.06 Msun and L = 29 +/- 6 Lsun; for beta Leo thetad = 1.47 +/- 0.09 mas, R = 1.75 +/- 0.11 Rsun, Mg = 1.78 +/- 0.46 Msun and L = 15 +/- 2 Lsun; for alpha Car thetad = 7.22 +/- 0.42 mas, R = 74.39 +/- 5.76 Rsun, Mg = 12.80+24.95-6.35 Msun and L = 14573 +/- 2268 Lsun and for alpha Cen A thetad = 8.80 +/- 0.51 mas, R = 1.27 +/- 0.08 Rsun, Mg = 1.35 +/- 0.22 Msun and L = 1.7 +/- 0.2 Lsun. 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. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA.}\fnmsep\thanks{Appendices A and B are only available in electronic form at http://www.edpsciences.org}

DOI: 10.1051/0004-6361:20021790
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