[en] We investigate the short-term optical variability of two γ Cas analogues, πAqr and BZ Cru, thanks to intensive ground-based spectroscopic and space-borne photometric monitorings. For both stars, low-amplitude (mmag) coherent photometric variability is detected. The associated signals display long-term amplitude variations, as in other Be stars. However, these signals appear at high frequencies, especially in πAqr, indicating p modes with a high degree l, a quite unusual feature amongst Be stars. While BZ Cru presents only low-level spectral variability, without clear periodicity, this is not the case of πAqr. In this star, the dominant photometric frequencies, near ∼12 d[SUP]-1[/SUP], are confirmed spectroscopically in separate monitorings taken during very different disc activity levels; the spectroscopic analysis suggests a probable tesseral nature for the mode.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël ; Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Pigulski, Andrzej; Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland
Rauw, Grégor ; Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Smith, Myron A.; NSF National Optical-Infrared Astronomy Research Laboratory, 950 N Cherry Ave, Tucson, AZ 85721, USA)
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