Red giant asteroseismic binaries in the Kepler field: Identifying gravitationally bound systems

Systems where two oscillating stars are observed in the same light curve—the so-called asteroseismic binaries (ABs)—arise from either chance alignments or gravitationally-bound stars. Asteroseismic binaries in the latter scenario offer unique opportunities to test stellar models, as they allow for asteroseismology and orbital dynamics to be used to determine precise stellar parameters of both components. Even though theoretical predictions suggest that around 200 asteroseismic binaries should exist in the Kepler data, only a handful have been detected. In this work, we increase the number of reported ABs by adding 44 new systems. We use Gaia DR3 astrometry, asteroseismic masses and evolutionary stages to assess the likelihood of the asteroseismic binaries in our sample being gravitationally bound. Contrary to predictions, we find that most of these ABs are likely chance alignments. Remarkably, the systems KIC 6501237 and KIC 1009454 have relative orbital motion and seismic properties in agreement with a wide binary scenario. These two candidates offer valuable cases for testing seismic scaling relations.