Analysis of Refined Parameters of the Eclipsing Hierarchical Triple Stellar System KOI-126
Abstract
KOI-126 was the first eclipsing hierarchical triple stellar system identified in the Kepler mission's photometry. The system contains a low-mass binary, KOI-126 B and C, with a period of P1 = 1.76713 ± 0.00019 days, orbiting a third star, KOI-126 A, with a period of P2 = 33.9214 ± 0.0013 days (Carter et al. 2011). The geometry and dynamics of the system are such that determination of the parameters of each of the three stars can be made accurately (better than a few percent) from the photometry alone, although using the radial velocities of star A yields an improvement of roughly a factor of 3-5 in precision. Carter et al. measured the masses of KOI-126 B and C to be 0.2413 ± 0.0030 M⊙ and 0.2127 ± 0.0026 M⊙, with radii 0.2543 ± 0.0014 R⊙, 0.2318 ± 0.0013 R⊙ respectively. KOI-126 A was measured to have a mass 1.347 ± 0.032 M⊙ and a radius 2.0254 ± 0.0098 R⊙ with an eccentricity around the low-mass binary of e2 = 0.3043 ± 0.0024. The original analysis employed a full dynamical-photometric model, utilizing a Levenberg-Marquardt algorithm and least-squares minimization, to fit the short-cadence (i.e. one minute exposures) photometric data from Kepler captured over a period of 247 days. The complete set of short-cadence data now covers a span of ~1,300 days. In light of the new data, and the valuable contribution that accurately measured fully-convective stars can offer to theoretical stellar models, we refined the parameters of this system. This new analysis was done using the same dynamical-photometric model developed by Carter et al. and incorporates a Markov chain Monte Carlo (MCMC) algorithm with least-squares minimization to fit the parameter space. We discuss the implication of our results in the context of evolutionary models for low mass stars. We acknowledge support from the National Science Foundation via the grant AST-1109928.
- Publication:
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American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22315521E