On X-ray pulsations in β Cephei-type variables

Abstract

Context. β Cep-type variables are early B-type stars that are characterized by oscillations observable in their optical light curves. At least one β Cep-variable also shows periodic variability in X-rays.
Aims: Here we study the X-ray light curves in a sample of β Cep-variables to investigate how common X-ray pulsations are for this type of stars.
Methods: We searched the Chandra and XMM-Newton X-ray archives and selected stars that were observed by these telescopes for at least three optical pulsational periods. We retrieved and analyzed the X-ray data for κ Sco, β Cru, and α Vir. The X-ray light curves of these objects were studied to test for their variability and periodicity.
Results: While there is a weak indication for X-ray variability in β Cru, we find no statistically significant evidence of X-ray pulsations in any of our sample stars. This might be due either to the insufficient data quality or to the physical lack of modulations. New, more sensitive observations should settle this question.

The scientific results reported in this article are based on observations made by the Chandra and XMM-Newton X-ray Observatories, data obtained from the Chandra and XMM-Newton Data Archives, and observations made by the Chandra and XMM-Newton and published previously in cited articles.