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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2009

Asteroseismology and interferometry of the red giant star ε Ophiuchi

Résumé

The GIII red giant star ε Oph has been found to exhibit several modes of oscillation by the MOST mission. We interpret the observed frequencies of oscillation in terms of theoretical radial p-mode frequencies of stellar models. Evolutionary models of this star, in both shell H-burning and core He-burning phases of evolution, are constructed using as constraints a combination of measurements from classical ground-based observations (for luminosity, temperature, and chemical composition) and seismic observations from MOST. Radial frequencies of models in either evolutionary phase can reproduce the observed frequency spectrum of ε Oph almost equally well. The best-fit models indicate a mass in the range of 1.85 ± 0.05 {M_&sun;} with radius of 10.55 ± 0.15{R_&sun;}. We also obtain an independent estimate of the radius of ε Oph with highly accurate interferometric observations in the infrared K' band, using the CHARA/FLUOR instrument. The measured limb-darkened disk angular diameter of ε Oph is 2.961 ± 0.007 mas. Together with the Hipparcos parallax, this translates into a photospheric radius of R = 10.39 ± 0.07 {R_&sun;}. The radius obtained from the asteroseismic analysis matches the interferometric value quite closely even though the radius was not constrained during the modelling.

Dates et versions

hal-03786360 , version 1 (23-09-2022)

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Citer

Anwesh Mazumdar, Antoine Merand, Pierre Demarque, Pierre Kervella, Caroline Barban, et al.. Asteroseismology and interferometry of the red giant star ε Ophiuchi. Astronomy and Astrophysics - A&A, 2009, 503, pp.521-531. ⟨10.1051/0004-6361/200912351⟩. ⟨hal-03786360⟩
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