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Published May 2016 | Published + Submitted
Journal Article Open

New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2


We present the discovery in Kepler's K2 mission observations and our follow-up radial velocity (RV) observations from Keck/HIRES for four eclipsing binary (EB) star systems in the young benchmark Pleiades and Hyades clusters. Based on our modeling results, we announce two new low mass (M_(tot) < 0.6 M⊙) EBs among Pleiades members (HCG 76 and MHO 9) and we report on two previously known Pleiades binaries that are also found to be EB systems (HII 2407 and HD 23642). We measured the masses of the binary HCG 76 to ≾2.5% precision, and the radii to ≾4.5% precision, which together with the precise effective temperatures yield an independent Pleiades distance of 132 ± 5 pc. We discuss another EB toward the Pleiades that is a possible but unlikely Pleiades cluster member (AK II 465). The two new confirmed Pleiades systems extend the mass range of Pleiades EB components to 0.2–2 M⊙. Our initial measurements of the fundamental stellar parameters for the Pleiades EBs are discussed in the context of the current stellar models and the nominal cluster isochrone, finding good agreement with the stellar models of Baraffe et al. at the nominal Pleiades age of 120 Myr. Finally, in the Hyades, we report a new low mass eclipsing system (vA 50) that was concurrently discovered and studied by Mann et al. We confirm that the eclipse is likely caused by a Neptune-sized transiting planet, and with the additional RV constraints presented here we improve the constraint on the maximum mass of the planet to be ≾1.2 M_(Jup).

Additional Information

© 2016 The American Astronomical Society. Received 2016 January 1; accepted 2016 February 4; published 2016 April 13. We thank the referee for helpful comments which led to significant improvement in the quality of this work. T.J.D thanks J. Southworth for helpful discussions regarding the use of JKTEBOP, and I. Crossfield for providing his MCMC transit fitting routine which was used to fit vA 50b. Support for this work was provided by NASA via grant NNX15AV62G. Some of the material presented herein is based upon work supported in 2015 by the National Science Foundation Graduate Research Fellowship under Grant DGE1144469. T.J.D. gratefully acknowledges research activities support from F. Córdova through the Neugebauer Scholarship. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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Published - aj_151_5_112.pdf

Submitted - 1602.01901v1.pdf


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