Briquet, M. ; Neiner, C. ; Aerts, C. ; Morel, T. ; Mathis, S. ; Reese, D. R. ; Lehmann, H. ; Costero, R. ; Echevarria, J. ; Handler, G. ; Kambe, E. ; Hirata, R. ; Masuda, S. ; Wright, D. ; Yang, S. ; Pintado, O. ; Mkrtichian, D. ; Lee, B. C. ; Han, I. ; Bruch, A. ; De Cat, P. ; Uytterhoeven, K. ; Lefever, K. ; Vanautgaerden, J. ; de Batz, B. ; Frémat, Y. ; Henrichs, H. ; Geers, V. C. ; Martayan, C. ; Hubert, A. M. ; Thizy, O. ; Tijani, A.

published in Monthly Notices of the Royal Astronomical Society, 427, pp. 483-493 (2012)

Abstract: We used extensive ground-based multisite and archival spectroscopy to derive observational constraints for a seismic modelling of the magnetic β Cep star V2052 Ophiuchi. The line-profile variability is dominated by a radial mode (f1 = 7.148 46 d-1) and by rotational modulation (Prot = 3.638 833 d). Two non-radial low-amplitude modes (f2 = 7.756 03 d-1 and f3 = 6.823 08 d-1) are also detected. The four periodicities that we found are the same as the ones discovered from a companion multisite photometric campaign and known in the literature. Using the photometric constraints on the degrees ℓ of the pulsation modes, we show that both f2 and f3 are prograde modes with (ℓ, m) = (4, 2) or (4, 3). These results allowed us to deduce ranges for the mass (M ∈ [8.2, 9.6] M⊙) and central hydrogen abundance (Xc ∈ [0.25, 0.32]) of V2052 Oph, to identify the radial orders n1 = 1, n2 = -3 and n3 = -2, and to derive an equatorial rotation velocity veq ∈ [71, 75] km s-1. The model parameters are in full agreement with the effective temperature and surface gravity deduced from spectroscopy. Only models with no or mild core overshooting (αov ∈ [0, 0.15] local pressure scale heights) can account for the observed properties. Such a low overshooting is opposite to our previous modelling results for the non-magnetic β Cep star θ Oph having very similar parameters, except for a slower surface rotation rate. We discuss whether this result can be explained by the presence of a magnetic field in V2052 Oph that inhibits mixing in its interior.

DOI: 10.1111/j.1365-2966.2012.21933.x
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