Finding binaries among Kepler pulsating stars from phase modulation of their pulsations

TL;DR

This paper introduces a photometric method using Kepler data to detect and characterize binary star systems through pulsation phase modulation, eliminating the need for spectroscopic observations.

Contribution

The novel approach allows for automated detection and orbital parameter estimation of binaries solely from Kepler light curves, including systems with multiple pulsation modes.

Findings

Successfully derived orbital parameters from light curves of pulsating stars.

Detected binaries with various orbital characteristics.

Demonstrated the method's ability to analyze systems with multiple pulsating components.

Abstract

We present a method for finding binaries among pulsating stars that were observed by the Kepler Mission. We use entire four-year light curves to accurately measure the frequencies of the strongest pulsation modes, then track the pulsation phases at those frequencies in 10-d segments. This produces a series of time-delay measurements in which binarity is apparent as a periodic modulation whose amplitude gives the projected light travel time across the orbit. Fourier analysis of this time-delay curve provides the parameters of the orbit, including the period, eccentricity, angle of ascending node and time of periastron passage. Differentiating the time-delay curve yields the full radial-velocity curve directly from the Kepler photometry, without the need for spectroscopy. We show examples with $\delta$ Scuti stars having large numbers of pulsation modes, including one system in which both components of the binary are pulsating. The method is straightforward to automate, thus radial velocity curves can be derived for hundreds of non-eclipsing binary stars from Kepler photometry alone.