Red giant asteroseismic binaries in the Kepler field: Identifying gravitationally bound systems
Espinoza-Rojas, Francisca; Themessl, Nathalie; Hekker, Saskia
- Publisher
- Zenodo
- Language
- en
Abstract
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.
Full text
Red giant asteroseismic binaries in the Kepler Field: Identifying gravitationally bound systems Francisca Espinoza-Rojas Nathalie Themeßl Saskia Hekker TASC9/KASC16 Workshop July 9th, 2025
Depending on difference KIC 5098145 Seismically unresolved Check poster #47 by Jeong Yun Choi 2
Seismically resolved KIC 6501237 Depending on difference KIC 5098145 Seismically unresolved Check poster #47 by Jeong Yun Choi 3
Predictions about asteroseismic binaries A new means for detecting non-eclipsing binaries 4
Predictions about asteroseismic binaries Adapted from Miglio et al. (2014) Fraction 0 0.1 0.2 0.3 00.5 1 1.5 2.0 Seismically resolved difference distribution 5 Miglio et al. (2014) ●~200 in Kepler long cadence data ●Small fraction is seismically resolved. ●Only 10% contamination from chance alignments A new means for detecting non-eclipsing binaries
Predictions about asteroseismic binaries 6 Adapted from Miglio et al. (2014) difference distribution Miglio et al. (2014) ●~200 in Kepler long cadence data ●Small fraction is seismically resolved. ●Only 10% contamination from chance alignments Mazzi et al. (2025) ●Not expected to interact during their evolution A new means for detecting non-eclipsing binaries Adapted from Miglio et al. (2014) Fraction 0 0.1 0.2 0.3 00.5 1 1.5 2.0 Seismically resolved
State of the art Only a handful of AB systems has been reported to date 7 Seismically unresolved Seismically resolved
Sample of ABs adfç 25 ABs (Bell at al. 2019) 15 ABs CAPASS (Espinoza-Rojas et al. in prep) 40 ABs 8
9 Motion on the sky: Astrometry How to detect gravitational interaction? Seismically resolved Wide orbits predicted Sample of ABs
Gravitationally bound? Based on Gaia DR3 astrometry and El-Badry et al. (2018, 2021) Espinoza-Rojas et al. (submitted) Chance alignments 16 Orbital velocity difference Projected separation Complete match
Gravitationally bound? Based on Gaia DR3 astrometry and El-Badry et al. (2018, 2021) Espinoza-Rojas et al. (submitted) Chance alignments 17 Orbital velocity difference Projected separation Complete match Single match P ~25% P ~50% WB WB
Are there any spatially unresolved systems? Based on Gaia multiplicity indicator: Renormalised Unit Weight Error (RUWE) Ruwe > 1.4 indicates potentially unresolved multiple systems 18 Espinoza-Rojas et al. (submitted) 7 RUWE candidates No match Single match Complete match
Ruwe > 1.4 indicates potentially unresolved multiple systems 19 Schimak (2023) Espinoza-Rojas et al. (submitted) KIC 10841730 Are there any spatially unresolved systems? Based on Gaia multiplicity indicator: Renormalised Unit Weight Error (RUWE) No match Single match Complete match
20 Espinoza-Rojas et al. (submitted) Radial velocity variability in ABs Based on Gaia radial velocity variability indicators (Katz et al. 2023) 6 RV candidates No match Single match Complete match
21 Espinoza-Rojas et al. (submitted) WB candidates RUWE candidates RV candidates Binary candidates 7 RUWE candidates 6 RV candidates 2 WB candidates
Takeaways Resolved asteroseismic binaries: ●~65% are chance alignments ●Two wide binary candidates: KIC 6501237 and KIC 10094545 ●7 RUWE and 6 RV binary candidates identified with Gaia multiplicity indicators 22 francisca.espinoz[email protected]g
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