Bibcode
Handler, G.; Shobbrook, R. R.; Uytterhoeven, K.; Briquet, M.; Neiner, C.; Tshenye, T.; Ngwato, B.; van Winckel, H.; Guggenberger, E.; Raskin, G.; Rodríguez, E.; Mazumdar, A.; Barban, C.; Lorenz, D.; Vandenbussche, B.; Şahin, T.; Medupe, R.; Aerts, C.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 424, Issue 3, pp. 2380-2391.
Fecha de publicación:
8
2012
Número de citas
29
Número de citas referidas
24
Descripción
We report a multisite photometric campaign for the β Cep stars
V2052 Oph and V986 Oph. 670 h of high-quality differential photoelectric
Strömgren, Johnson and Geneva time-series photometry was obtained
with eight telescopes on five continents during 182 nights. Frequency
analyses of the V2052 Oph data enabled the detection of three pulsation
frequencies, the first harmonic of the strongest signal, and the
rotation frequency with its first harmonic. Pulsational mode
identification from analysing the colour amplitude ratios confirms the
dominant mode as being radial, whereas the other two oscillations are
most likely l = 4. Combining seismic constraints on the inclination of
the rotation axis with published magnetic field analyses we conclude
that the radial mode must be the fundamental mode. The rotational light
modulation is in phase with published spectroscopic variability, and
consistent with an oblique rotator for which both magnetic poles pass
through the line of sight. The inclination of the rotation axis is
54° < i < 58° and the magnetic obliquity 58° <
β < 66°. The possibility that V2052 Oph has a magnetically
confined wind is discussed. The photometric amplitudes of the single
oscillation of V986 Oph are most consistent with an l = 3 mode, but this
identification is uncertain. Additional intrinsic, apparently temporally
incoherent light variations of V986 Oph are reported. Different
interpretations thereof cannot be distinguished at this point, but this
kind of variability appears to be present in many OB stars. The
prospects of obtaining asteroseismic information for more rapidly
rotating β Cep stars, which appear to prefer modes of higher l, are
briefly discussed.
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