Aerts, C.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium Department of Astrophysics, Radboud University Nijmegen, 6500 GL Nijmegen, The Netherlands]
Cuypers, J.[Koninklijke Sterrenwacht van België, Ringlaan 3, 1180 Brussel, Belgium]
Yakut, K.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium Department of Astronomy and Space Sciences, Faculty of Science, University of Ege, 35100 Izmir, Turkey]
Scuflaire, Richard[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Evol. et stabilité des étoiles et des amas d'étoiles (ESEA) >]
Dupret, Marc-Antoine[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique >]
Uytterhoeven, K.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy mercator Telescope, Calle Alvarez de Abreu 70, 38700 Santa Cruz de La Palma, Spain]
van Winckel, H.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium]
Raskin, G.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium mercator Telescope, Calle Alvarez de Abreu 70, 38700 Santa Cruz de La Palma, Spain]
Davignon, G.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium mercator Telescope, Calle Alvarez de Abreu 70, 38700 Santa Cruz de La Palma, Spain]
Le Guillou, L.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium mercator Telescope, Calle Alvarez de Abreu 70, 38700 Santa Cruz de La Palma, Spain]
van Malderen, R.[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium]
[en] stars: early-type ; stars: variables: general ; stars: oscillations
[en] Aims. We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, beta Cep, and Maia stars after the analysis of their hipparcos data. We analysed our new seven passband geneva data collected for these stars during the first three years of scientific operations of the mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes. Methods: We searched for frequencies in all the geneva passbands and colours by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. The modes were identified by applying the method of photometric amplitudes for which we calculated a large, homogeneous grid of equilibrium models to perform a pulsational stability analysis. When both the radius and the projected rotational velocity of an object are known, we determined a lower limit for the rotation frequency to estimate the expected frequency spacings in rotationally split pulsation modes. Results: We detected 61 frequencies, among which 33 are new. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid beta Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant. All the Maia candidates were reclassified into other variability classes. We performed mode identification for the pulsating variables for the first time. The most probable l value is 0, 1, 2, and 4 for 1, 31, 9, and 5 modes, respectively, including only 4 unambiguous identifications. For 7 stars we cannot rule out that some of the observed frequencies belong to the same rotationally split mode. For 4 targets we may begin to resolve close frequency multiplets. Based on observations collected with the p7 photometer attached to the Flemish 1.2-m mercator telescope situated at the Roque de los Muchachos observatory on La Palma (Spain). Section [see full textsee full text], including Figs. is only available in electronic form at http://www.aanda.org, and Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/463/243
[Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium]
