Stellar Properties of KIC 8736245: An Eclipsing Binary with a Solar-type Star Leaving the Main Sequence
| Autor: | Donald R. Short, Samuel N. Quinn, William F. Welsh, Stephen R. Kane, Richard A. Wade, Gur Windmiller, Tara Fetherolf, Jerome A. Orosz |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Stellar rotation Starspot FOS: Physical sciences Astronomy and Astrophysics Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Type (model theory) Light curve Orbital period 01 natural sciences Photometry (astronomy) Stars Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science 0103 physical sciences Binary star Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences |
| DOI: | 10.48550/arxiv.1909.10573 |
| Popis: | There is a well-known stellar parameter discrepancy for late K and M dwarfs, in that the observed radii and temperatures are often respectively larger and cooler than predicted by theory by several percent. In an on-going effort to elucidate this issue, we examine the double-lined Kepler eclipsing binary star system KIC 8736245. We supplement the near-continuous 4-year Kepler light curve with ground-based multicolor photometry from Mount Laguna Observatory and spectroscopy from the Hobby-Eberly Telescope. The binary has an edge-on, circular 5.07 day orbit with stellar masses equal to $0.987\pm0.009$ and $0.782\pm0.009\,\text{M}_\odot$ and radii of $1.311 \pm 0.006$ and $0.804 \pm 0.004\,\text{R}_\odot$, respectively, and an estimated age of 7-9 Gyr. We find that the stellar radii are consistent with theoretical models within the uncertainties, whereas the temperature of the secondary star is $\sim$6% cooler than predicted. An important aspect of this work is that the uncertainties derived from a single epoch (individual night of observations) underestimates the overall system parameter uncertainties due to the effect of the 1-4% fluctuations caused by stellar activity. Our error estimates come from the spread in parameters measured at 8 epochs. From the periodicities in the light curve and from the eclipse times, we measure candidate spin periods to be approximately 4.98 and 5.87 days for the primary and secondary star. Surprisingly, these imply super- and sub-synchronous rotation compared to the orbital period. Thus KIC 8736245 serves as an interesting case study for the exchange of angular momentum and general stellar astrophysics as stars in binaries evolve off the main sequence. Comment: 15 pages, 12 figures, accepted to The Astronomical Journal |
| Databáze: | OpenAIRE |
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