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Published December 20, 2019 | Submitted + Published
Journal Article Open

Eclipsing binaries in the open cluster Ruprecht 147. II: EPIC 219568666

Abstract

We report our spectroscopic monitoring of the detached, grazing, and slightly eccentric 12 day double-lined eclipsing binary EPIC 219568666 in the old nearby open cluster Ruprecht 147. This is the second eclipsing system to be analyzed in this cluster, following our earlier study of EPIC 219394517. Our analysis of the radial velocities combined with the light curve from the K2 mission yields absolute masses and radii for EPIC 219568666 of M₁ = 1.121 ± 0.013 M☉ and R₁ = 1.1779 ± 0.0070 R☉ for the F8 primary and M₂ = 0.7334 ± 0.0050 M☉ and R₂ = 0.640 ± 0.017 R☉ for the faint secondary. Comparison with current stellar evolution models calculated for the known metallicity of the cluster points to a primary star that is oversized, as is often seen in active M dwarfs, but this seems rather unlikely for a star of its mass and with a low level of activity. Instead, we suspect a subtle bias in the radius ratio inferred from the photometry, despite our best efforts to avoid it, which may be related to the presence of spots on one or both stars. The radius sum for the binary, which bypasses this possible problem, indicates an age of 2.76 ± 0.61 Gyr, which is in good agreement with a similar estimate from the binary in our earlier study.

Additional Information

© 2019 The American Astronomical Society. Received 2019 October 1; revised 2019 November 4; accepted 2019 November 4; published 2019 December 16. The spectroscopic observations of EPIC 219568666 were gathered with the help of P. Berlind, M. Calkins, G. Esquerdo, and D. Latham. J. Mink is thanked for maintaining the CfA echelle database. We are also grateful to J. Irwin for implementing changes in the eb program that facilitated the present analysis, and to the anonymous referee for helpful comments and suggestions. G.T. acknowledges partial support from NASA's Astrophysics Data Analysis Program through grant 80NSSC18K0413, and to the National Science Foundation (NSF) through grant AST-1509375. J.L.C. is supported by the NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1602662, and by NASA under grant NNX16AE64G issued through the K2 Guest Observer Program (GO 7035). This work was performed in part under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. The research has made use of the SIMBAD and VizieR databases, operated at the CDS, Strasbourg, France, and of NASA's Astrophysics Data System Abstract Service. The research was made possible through the use of the AAVSO Photometric All-Sky Survey (APASS), funded by the Robert Martin Ayers Sciences Fund. Data products were also used from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. The work has also made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The computational resources used for this research include the Smithsonian Institution's "Hydra" High Performance Cluster.

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Published - Torres_2019_ApJ_887_109.pdf

Submitted - 1911.02579.pdf

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Created:
August 22, 2023
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