Research Note

On X-ray pulsations in β Cephei-type variables^⋆

¹ Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
e-mail: lida@astro.physik.uni-potsdam.de
² Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139, USA
³ Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁴ Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663, USA
⁵ South African Astronomical Observatory, PO Box 9, Observatory 7935 Cape Town, South Africa

Received: 16 February 2015
Accepted: 9 March 2015

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.