A quintuple star system containing two eclipsing binaries

• Published in: Monthly notices of the Royal Astronomical Society 2016-10, Vol.462 (2), p.1812-1825
• Main Authors: Rappaport, S., Lehmann, H., Kalomeni, B., Borkovits, T., Latham, D., Bieryla, A., Ngo, H., Mawet, D., Howell, S., Horch, E., Jacobs, T. L., LaCourse, D., Sódor, Á., Vanderburg, A., Pavlovski, K.
• Format: Article
• Language: English
• Subjects: Adaptive optics; Astronomy; Binary stars; Double stars; Eclipsing binary stars; Imaging; Orbits; Radial velocity; Scientific imaging; Separation; Stars & galaxies; Stellar systems
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw1745

We present a quintuple star system that contains two eclipsing binaries. The unusual architecture includes two stellar images separated by 11 arcsec on the sky: EPIC 212651213 and EPIC 212651234. The more easterly image (212651213) actually hosts both eclipsing binaries which are resolved within that image at 0.09 arcsec, while the westerly image (212651234) appears to be single in adaptive optics (AO), speckle imaging, and radial velocity (RV) studies. The ‘A’ binary is circular with a 5.1-d period, while the ‘B’ binary is eccentric with a 13.1-d period. The γ velocities of the A and B binaries are different by ∼10 km s−1. That, coupled with their resolved projected separation of 0.09 arcsec, indicates that the orbital period and separation of the ‘C’ binary (consisting of A orbiting B) are ≃65 yr and ≃25 au, respectively, under the simplifying assumption of a circular orbit. Motion within the C orbit should be discernible via future RV, AO, and speckle imaging studies within a couple of years. The C system (i.e. 212651213) has an RV and proper motion that differ from that of 212651234 by only ∼1.4 km s−1 and ∼3 mas yr−1. This set of similar space velocities in three dimensions strongly implies that these two objects are also physically bound, making this at least a quintuple star system.