New Beta Cephei Stars from the KELT Project

Abstract

We present the results of a search for Galactic β Cephei stars, which are massive pulsating stars with both pressure modes and mixed modes. Thus, these stars can serve as benchmarks for seismological studies of the interiors of massive stars. We conducted the search by performing a frequency analysis on the optical light curves of known Oand B-type stars with data from the Kilodegree Extremely Little Telescope exoplanet survey. We identify 113 β Cephei stars, of which 86 are new discoveries, which altogether represent a 70% increase in the number currently known. An additional 97 candidates are identified. Among our targets, we find five new eclipsing binaries and 22 stars with equal frequency spacings suggestive of rotational splitting of nonradial pulsation modes. Candidates for runaway stars among our targets and a number of interesting individual objects are discussed. Most of the known and newly discovered β Cephei stars will be observed by the Transiting Exoplanet Survey Satellite mission, providing by far the most comprehensive observational data set of massive main-sequence pulsating stars of sufficient quality for detailed asteroseismic studies. Future analysis of these light curves has the potential to dramatically increase our understanding of the structure of stellar interiors and the physical processes taking place therein. Unified Astronomy Thesaurus concepts: Beta Cepheid variable stars (148); Asteroseismology (73); Stellar oscillations (1617); Multi-periodic variable stars (1079); Pulsating variable stars (1307); Short period variable stars (1453); Early-type variable stars (432); Light curves (918); Light curve classification (1954); Surveys (1671); B stars (128) Supporting material: data behind figure, machine-readable tables

Characterization of the variability in the O+B eclipsing binary HD 165246

“…The Transiting Exoplanet Survey Satellite (TESS; Ricker et al 2015) is currently assembling sub-mmag precision space-based photometry of high-mass stars across the entire sky. This sample is yielding high quality observations of more massive stars than any homogeneous database to date (see e.g., Burssens et al 2020;Labadie-Bartz et al 2020). Characterization of the variability (or lack thereof) in these stars is providing the basis upon which predictions of physical mechanisms can be tested.…”

Massive Star Modeling and Nucleosynthesis

“…While the overall picture of these analyses would advocate a 50%-50% fraction of differentially and rigidly rotating β Cephei stars, this sample is way too small to give us firm answers about the rotation profiles in massive stars, and only when statistically-significant large asteroseismic surveys will have yielded their results will we be able to assess whether the same problem of angular momentum occurs in massive stars as in low-mass stars. We might not have to wait too long: Labadie- Bartz et al (2020) have identify 86 new β Cephei stars and 97 candidates from the KELT project (Kilodegree Extremely Little Telescope exoplanet survey) that will be included in the target list of TESS (Transiting Exoplanet Survey Satellite).…”

Classifying Be star variability with TESS I: the southern ecliptic

“…(perhaps there are low amplitude frequency groups below the detection threshold), and it is also sometimes observed that the strength of groups and/or their most prominent frequencies can significantly vary over time (Smith et al 2006;Borre et al 2020;Labadie-Bartz & Carciofi 2020a, Labadie-Bartz et al 2020, so that the lack of observed groups at the time when a given star is observed by TESS does not neces-sarily mean that groups have not existed in the past (or will not become more prominent in the future).…”