Article Dans Une Revue Astronomy & Astrophysics - A&A Année : 2001

The XMM-Newton view of stellar coronae: High-resolution X-ray spectroscopy of Capella

Résumé

We present the high-resolution RGS X-ray spectrum of the stellar binary Capella observed by the XMM-Newton satellite. A multi-thermal approach has first been applied to fit the data and derive elemental abundances. Using the latter, the emission measure distribution has been reconstructed using a Chebychev polynomial fit. Its shape is found to display a sharp peak around 7 MK, consistent with previous EUVE and ASCA results. A smaller but significant amount of emission measure is required around 1.8 MK in order to explain the O Vii He-like triplet and the C Vi Lyalpha line. We have applied the temperature diagnostics of dielectronic recombination satellite lines to the He-like O Vii triplet to constrain the cool plasma temperature, and have obtained a lower limit consistent with the global reconstruction of the emission measure distribution. We have used line ratios from the forbidden, intercombination, and resonance lines of the O Vii triplet to derive an average density for the cool coronal plasma (ne <1 1010 cm-3). Implications for the coronal structure of Capella are discussed. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).
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Dates et versions

hal-02336082 , version 1 (17-01-2025)

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Marc Audard, E. Behar, M. Güdel, A. J. J. Raassen, D. Porquet, et al.. The XMM-Newton view of stellar coronae: High-resolution X-ray spectroscopy of Capella. Astronomy & Astrophysics - A&A, 2001, 365 (1), pp.L329-L335. ⟨10.1051/0004-6361:20000246⟩. ⟨hal-02336082⟩
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