Multiperiodicity in the light variations of the β Cephei star β Crucis

¹ Koninklijke Sterrenwacht van België, Ringlaan 3, 1180 Brussel, Belgium
² Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3030 Heverlee, Belgium e-mail: Conny.Aerts@ster.kuleuven.ac.be
³ Department of Physics, US Air Force Academy, Colorado Springs, CO 80840, USA e-mail: Derek.Buzasi@usafa.af.mil
⁴ Interferometry Science Center, California Institute of Technology, Pasadena, CA 91125, USA e-mail: jcatanz@ix.netcom.com
⁵ Infrared Processing and Analysis Center, Mailstop 100-22, California Institute of Technology, Pasadena, CA 91125, USA e-mail: tim@ipac.caltech.edu
⁶ SIRTF Science Center, Mailstop 314-6, California Institute of Technology, Pasadena, CA 91125, USA e-mail: laher@ipac.caltech.edu

Corresponding author: J. Cuypers, Jan.Cuypers@oma.be

Received: 11 April 2002
Accepted: 20 June 2002

Abstract

High-resolution spectroscopic observations have led recently to the discovery that the β Cephei star β Crucis (Mimosa) is multiperiodic with at least three non-radial pulsation modes. Data obtained by the star tracker of the WIRE satellite have now allowed us to confirm this multiperiodicity in the light variations. A total of 5 million observations covering 17 days was analysed and the three main periods we find in this work are in perfect agreement with the results derived from the line profile variations. The photometric amplitudes are small (3, 2.7 and 0.6 millimag for the dominant modes), but this is not surprising in view of the mode identifications derived earlier from the line profiles. Additional periods of low-amplitude modes (between 0.2–0.3 mmag) are also derived, including one suggested earlier by the radial velocity data.