Beta Cephei stars in the ASAS-3 data. II. 103 new Beta Cephei stars and a discussion of low-frequency modes

TL;DR

This study identified 103 new Beta Cephei stars from ASAS-3 data, including hybrid pulsators and binary components, significantly expanding the known sample for seismic analysis and stellar pulsation research.

Contribution

The paper reports the discovery of 103 new Beta Cephei stars, nearly doubling the known population, and highlights the identification of hybrid pulsators and binary systems for seismic studies.

Findings

Discovered 103 new Beta Cephei stars.

Identified 5 candidate hybrid Beta Cephei/SPB pulsators.

Found Beta Cephei pulsations in late O-type stars.

Abstract

We analysed ASAS-3 photometry of bright early-type stars with the goal of finding new Beta Cephei stars. We were particularly interested in stars that would be good for seismic analysis, i.e., stars that (i) have a large number of excited modes, (ii) show rotationally split modes, (iii) are components of eclipsing binary systems, (iv) have low-frequency modes, that is, are hybrid Beta Cephei/SPB stars. Our study was made with a homogeneous sample of over 4100 stars having MK spectral type B5 or earlier. For these stars, the ASAS-3 photometry was analysed by means of a Fourier periodogram. We have discovered 103 Beta Cephei stars, nearly doubling the number of previously known stars of this type. Among these stars, four are components of eclipsing binaries, seven have modes equidistant or nearly equidistant in frequency. In addition, we found five Beta Cephei stars that show low-frequency periodic variations, very likely due to pulsations. We therefore regard them as candidate hybrid Beta Cephei/SPB pulsators. All these stars are potentially very useful for seismic modeling. Moreover, we found Beta Cephei-type pulsations in three late O-type stars and fast period changes in one, HD 168050.