Photodynamical analysis of the triply eclipsing hierarchical triple system EPIC 249432662

Abstract

Using Campaign 15 data from the K2 mission, we have discovered a\ntriply-eclipsing triple star system: EPIC 249432662. The inner eclipsing binary\nsystem has a period of 8.23 days, with shallow $\\sim$3% eclipses. During the\nentire 80-day campaign, there is also a single eclipse event of a third-body in\nthe system that reaches a depth of nearly 50% and has a total duration of 1.7\ndays, longer than for any previously known third-body eclipse involving\nunevolved stars. The binary eclipses exhibit clear eclipse timing variations. A\ncombination of photodynamical modeling of the lightcurve, as well as seven\nfollow-up radial velocity measurements, has led to a prediction of the\nsubsequent eclipses of the third star with a period of 188 days. A campaign of\nfollow-up ground-based photometry was able to capture the subsequent pair of\nthird-body events as well as two further 8-day eclipses. A combined\nphoto-spectro-dynamical analysis then leads to the determination of many of the\nsystem parameters. The 8-day binary consists of a pair of M stars, while most\nof the system light is from a K star around which the pair of M stars orbits.\n