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arXiv · 2202.00021

Enhancement of Double-Close-Binary Quadruples

Gavin B. Fezenko·Hsiang-Chih Hwang·Nadia L. Zakamska
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Abstract

Double-close-binary quadruples (2+2 systems) are hierarchical systems of four stars where two short-period binary systems move around their common center of mass on a wider orbit. Using Gaia Early Data Release 3, we search for comoving pairs where both components are eclipsing binaries. We present eight 2+2 quadruple systems with inner orbital periods of $<$ 0.4 days and with outer separations of $\gtrsim 1000$ AU. All but one system are newly discovered by this work, and we catalog their orbital information measured from their light curves. We find that the occurrence rate of 2+2 quadruples is 7.3 $\pm$ 2.6 times higher than what is expected from random pairings of field stars. At most a factor of $\sim$2 enhancement may be explained by the age and metallicity dependence of the eclipsing binary fraction in the field stellar population. The remaining factor of $\sim$3 represents a genuine enhancement of the production of short-period binaries in wide-separation ($>10^3$ AU) pairs, suggesting a close binary formation channel that may be enhanced by the presence of wide companions.

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Gavin B. Fezenko, Hsiang-Chih Hwang, Nadia L. Zakamska. 2022-01-31. Enhancement of Double-Close-Binary Quadruples. https://doi.org/10.1093/mnras%2Fstac309

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