Systematic search for stellar pulsators in the eclipsing binaries observed byKepler

Abstract

Eclipsing binaries (EBs) are unique targets for measuring precise stellar properties and constrain stellar evolution models. In particular, it is possible to measure at the percent level masses and radii of both components of a double-lined spectroscopic EB. Since the advent of high-precision photometric space missions (MOST, CoRoT, Kepler, BRITE, TESS), the use of stellar pulsation properties to infer stellar interiors and dynamics constitutes a revolution for low-mass star studies. The Kepler mission has led to the discovery of thousands of classical pulsators such as δ Scuti and solar-like oscillators (main sequence and evolved), but also almost 3000 EBs with orbital periods shorter than 1100 days. We report the first systematic search for stellar pulsators in the entire Kepler eclipsing binary catalog. The focus is mainly aimed at discovering δ Scuti, γ Doradus, red giant, and tidally excited pulsators. We developed a data inspection tool (DIT) that automatically produces a series of plots from the Kepler light-curves that allows us to visually identify whether stellar oscillations are present in a given time series. We applied the DIT to the whole Kepler eclipsing binary database and identified 303 systems whose light curves display oscillations, including 163 new discoveries. A total of 149 stars are flagged as δ Scuti (100 from this paper), 115 stars as γ Doradus (69 new), 85 stars as red giants (27 new), 59 as tidally excited oscillators (29 new). There is some overlap among these groups, as some display several types of oscillations. Despite many of these systems are likely to be false positives, i. e., when an EB light curve is blended with a pulsator, this catalog gathers a vast sample of systems that are valuable for a better understanding of stellar evolution.

The single-sided pulsator CO Camelopardalis

“…This problem of why some stars pulsate and others do not is not understood for close binary stars (Gaulme & Guzik 2019).…”

“…Hence we have been searching for stars with their pulsation axis aligned with the tidal axis for over 40 years, since the discovery of oblique pulsation. Gaulme & Guzik (2019) conducted the first systematic survey of pulsating stars in eclipsing binaries in the Kepler eclipsing binary catalogue, which includes stars with orbital periods as short as 0.05 d. They found 13 systems with periods less than 0.5 d that show γ Dor or δ Sct pulsations, although they could not rule out false positives, e.g., potential third components, or background contamination. Interestingly, they could not come to a conclusion about whether being in a close binary suppresses pulsation.…”

“…We ourselves have (unsystematically) also noticed in our examination of both Kepler and TESS data that close binary stars with components in the δ Sct instability strip often show no pulsations at all, but some do. Gaulme & Guzik (2019) have made a good start in examining this. Now the statistics of pulsations in close binary stars needs to be studied even more systematically, in comparison with the statistics for pulsations in wide binaries and single stars.…”

Active red giants: Close binaries versus single rapid rotators

“…We developed an automatic pipeline -the Data Inspection Tool, hereafter DIT -to analyze the whole sample, which cleans the light curves and extracts the properties of both rotational modulation and solar-like oscillations. The code is similar to that described in Gaulme & Guzik (2019) to look for stellar pulsators A63, page 4 of 18 Fig. 3.…”

Four New Γ Doradus Variables in Eclipsing Binaries: Revised Pulsation Period Relations

“…These requirements make the Kepler space telescope an excellent instrument to study the pulsational properties of the γ Dor variables, with its very high precision and continuous data spanning over 4 years. Using Kepler data, more than 100 eclipsing binaries with a γ Dor component were discovered so far (Gaulme & Guzik 2019). Ibanoglu et al (2018) compiled a comprehensive catalogue of γ Dor variables and showed that the pulsation periods of binary γ Dor variables are proportional to their orbital periods and pulsation constants (Q), but inversely proportional to the fractional radii of the pulsating components.…”