β Cephei Pulsations in the High-mass Eclipsing System CW Cephei

CW Cep is an early B-type eclipsing binary with mass measurement precisions better than 1%. We report the discovery of pulsation signatures in the Transiting Exoplanet Survey Satellite time-series data of the system observed during Sectors 17 and 18. Our binary modeling indicates that the target star is a partially eclipsing detached system with masses of 12.95 M and 11.88 M and radii of 5.52 R and 5.09 R in an eccentric orbit of e = 0.0305. The distance to the eclipsing system, 928 36 pc, is much more precise than the Gaia distance of 962 453 pc. Applying multifrequency analyses to the residual light curve in the outside-eclipse part, we detected 13 significant signals in two frequency regions. Six frequencies below 1 day(-1) appeared to be mostly orbital harmonic and combination terms, or sidelobes due to insufficient removal of the binary effects. In contrast, seven frequencies clustered around 2.73 day(-1) and 5.34 day(-1) could be considered beta Cep-type pulsations. Our results represent the second discovery of beta Cep pulsations present in double-lined eclipsing binaries with precise masses and, hence, CW Cep serves as an important test bed for the asteroseismic modeling of high-mass stars.

Automated summary

CW Cep is an early B-type eclipsing binary system with precise mass measurements, showing pulsation signatures that could be orbital harmonics or secondary frequencies. These findings contribute to the asteroseismic modeling of high-mass stars.