ISO-SWS calibration and the accurate modelling of cool-star atmospheres - III. A0 to G2 stars

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

doi:10.1051/0004-6361:20021790

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Volume 400 / No 2 (March III 2003)

A&A, 400 2 (2003) 695-707

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Issue		A&A Volume 400, Number 2, March III 2003


Page(s)		695 - 707
Section		Stellar atmospheres
DOI		https://doi.org/10.1051/0004-6361:20021790
Published online		12 June 2003

A&A 400, 695-707 (2003)

ISO-SWS calibration and the accurate modelling of cool-star atmospheres ^*,^**

III. A0 to G2 stars

L. Decin¹, B. Vandenbussche¹, C. Waelkens¹, K. Eriksson², B. Gustafsson², B. Plez³ and A. J. Sauval⁴

¹ Instituut voor Sterrenkunde, KULeuven, Celestijnenlaan 200B, 3001 Leuven, Belgium
² Institute for Astronomy and Space Physics, Box 515, 75120 Uppsala, Sweden
³ GRAAL - CC72, Université de Montpellier II, 34095 Montpellier Cedex 5, France
⁴ Observatoire Royal de Belgique, Avenue Circulaire 3, 1180 Bruxelles, Belgium

Corresponding author: L. Decin, Leen.Decin@ster.kuleuven.ac.be

Received: 22 November 2001
Accepted: 2 December 2002

Abstract

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. ([CITE]), each of these stars is discussed individually in this paper. As demonstrated in Decin et al. ([CITE]), 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 ( $\theta_{\rm d}$ ) 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 $\mbox{$\theta_{\rm d}$}= 3.35 \pm 0.20$ mas, $R = 2.79 \pm 0.17$ $R_{\odot}$ , $M_{\rm g} = 2.54 \pm 1.21$ $M_{\odot}$ and $L = 61 \pm 9$ $L_{\odot}$ ; for Sirius $\mbox{$\theta_{\rm d}$}= 6.17 \pm 0.38$ mas, $R = 1.75 \pm 0.11$ $R_{\odot}$ , $M_{\rm g} = 2.22 \pm 1.06$ $M_{\odot}$ and $L = 29 \pm 6$ $L_{\odot}$ ; for β Leo $\mbox{$\theta_{\rm d}$}= 1.47 \pm 0.09$ mas, $R = 1.75 \pm 0.11$ $R_{\odot}$ , $M_{\rm g} = 1.78 \pm 0.46$ $M_{\odot}$ and $L = 15 \pm 2$ $L_{\odot}$ ; for α Car $\mbox{$\theta_{\rm d}$}= 7.22 \pm 0.42$ mas, $R = 74.39 \pm 5.76$ $R_{\odot}$ , $M_{\rm g} = 12.80^{+24.95}_{-6.35}$ $M_{\odot}$ and $L = 14573 \pm 2268$ $L_{\odot}$ and for α Cen A $\mbox{$\theta_{\rm d}$}= 8.80 \pm 0.51$ mas, $R = 1.27 \pm 0.08$ $R_{\odot}$ , $M_{\rm g} = 1.35 \pm 0.22$ $M_{\odot}$ and $L = 1.7 \pm 0.2$ $L_{\odot}$ . 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.

Key words: infrared: stars / stars: atmospheres / stars: fundamental parameters

^*

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.

^**

Appendices A and B are only available in electronic form at http://www.edpsciences.org

© ESO, 2003

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ISO-SWS calibration and the accurate modelling of cool-star atmospheres *,**

III. A0 to G2 stars

ISO-SWS calibration and the accurate modelling of cool-star atmospheres ^*,^**