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Multisite spectroscopic seismic study of the beta Cep star V2052 Oph: inhibition of mixing by its magnetic field | M. Briquet
; C. Neiner
; C. Aerts
; T. Morel
; S. Mathis
; D.R. Reese
; H. Lehmann
; R. Costero
; J. Echevarria
; G. Handler
; E. Kambe
; R. Hirata
; S. Masuda
; D. Wright
; S. Yang
; O. Pintado
; D. Mkrtichian
; B.-C. Lee
; I. Han
; A. Bruch
; P. De Cat
; K. Uytterhoeven
; K. Lefever
; J. Vanautgaerden
; B. de Batz
; Y. Frémat
; H. Henrichs
; V.C. Geers
; C. Martayan
; A.M. Hubert
; O. Thizy
; A. Tijani
; | Date: |
21 Aug 2012 | Abstract: | We used extensive ground-based multisite and archival spectroscopy to derive
observational constraints for a seismic modelling of the magnetic beta Cep star
V2052 Ophiuchi. The line-profile variability is dominated by a radial mode
(f_1=7.14846 d^{-1}) and by rotational modulation (P_rot=3.638833 d). Two
non-radial low-amplitude modes (f_2=7.75603 d^{-1} and f_3=6.82308 d^{-1}) are
also detected. The four periodicities that we found are the same as the ones
discovered from a companion multisite photometric campaign (Handler et al.
2012) and known in the literature. Using the photometric constraints on the
degrees l of the pulsation modes, we show that both f_2 and f_3 are prograde
modes with (l,m)=(4,2) or (4,3). These results allowed us to deduce ranges for
the mass (M in [8.2,9.6] M_o) and central hydrogen abundance (X_c in
[0.25,0.32]) of V2052 Oph, to identify the radial orders n_1=1, n_2=-3 and
n_3=-2, and to derive an equatorial rotation velocity v_eq in [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 (alpha_ov in [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 beta Cep star theta 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. | Source: | arXiv, 1208.4250 | Services: | Forum | Review | PDF | Favorites |
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