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KIC 4142768: An Evolved Gamma Doradus/Delta Scuti Hybrid Pulsating Eclipsing Binary with Tidally Excited Oscillations

Guo, Zhao and Fuller, Jim and Shporer, Avi and Li, Gang and Hambleton, Kelly and Manuel, Joseph and Murphy, Simon and Isaacson, Howard (2019) KIC 4142768: An Evolved Gamma Doradus/Delta Scuti Hybrid Pulsating Eclipsing Binary with Tidally Excited Oscillations. Astrophysical Journal, 885 (1). Art. No. 46. ISSN 1538-4357.

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We present the characterization of KIC 4142768, an eclipsing binary with two evolved A-type stars in an eccentric orbit with a period of 14 days. We measure the fundamental parameters of the two components (M₁ = 2.05M_⊙, R₁ = 2.96R_⊙ and M₂ = 2.05M_⊙, R₂ = 2.51R_⊙) by combining Kepler photometry and spectra from the Keck HIRES. The measured surface rotation rates are only one-fifth of the pseudo-synchronous rate of the eccentric orbit. The Fourier spectrum of the light curve reveals hybrid pulsations of δ Scuti and γ Doradus type, with pulsation frequencies at about 15–18 day⁻¹ for p modes and about 0.2–1.2 day⁻¹ for low-frequency g modes. Some of the g modes are exact orbital harmonics and are likely tidally excited. Their pulsation amplitudes and phases both agree with predictions from linear tidal theory for l = 2, m = 2 prograde modes. We examine the period spacing patterns in the self-driven g modes and identify them mostly as prograde sectoral dipole modes. The unstable frequency range and frequency spacing of the p modes and the inferred asymptotic g-mode period spacings both agree with the stellar model for the primary star evolved to a late stage of the main sequence. The inferred rotation rate of the convective core boundary is very slow, similar to the small surface rotation rate inferred from the spectroscopy. The measured surface and near-core rotation rates provide constraints for testing the mechanism of angular momentum transfer and tidal synchronization in evolved eccentric binary star systems.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Guo, Zhao0000-0002-0951-2171
Fuller, Jim0000-0002-4544-0750
Shporer, Avi0000-0002-1836-3120
Li, Gang0000-0001-9313-251X
Hambleton, Kelly0000-0001-5473-856X
Murphy, Simon0000-0002-5648-3107
Isaacson, Howard0000-0002-0531-1073
Additional Information:© 2019 The American Astronomical Society. Received 2019 July 12; revised 2019 September 3; accepted 2019 September 4; published 2019 October 29. We are in debt to the referee whose suggestions improve the quality of this paper. We thank the Kepler team for making such exquisite data publicly available, and the MESA team for developing excellent modeling tools. Z.G. thanks Jerry Orosz for making the ELC code available. The usage of programs developed by the team of Douglas Gies in Georgia State University is acknowledged. This work is partially supported by the Polish NCN grants grant 2015/18/A/ST9/00578. J.F. acknowledges support by an Innovator Grant from The Rose Hills Foundation and the Sloan Foundation through grant FG-2018-10515. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Group:TAPIR, Astronomy Department
Funding AgencyGrant Number
National Science Centre (Poland)2015/18/A/ST9/00578
Rose Hills FoundationUNSPECIFIED
Alfred P. Sloan FoundationFG-2018-10515
Subject Keywords:Stellar oscillations; Asteroseismology; Binary stars; Eclipsing binary stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Stellar oscillations (1617); Asteroseismology (73); Binary stars (154); Eclipsing binary stars (444)
Record Number:CaltechAUTHORS:20191029-111719772
Persistent URL:
Official Citation:Zhao Guo et al 2019 ApJ 885 46
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99533
Deposited By: Tony Diaz
Deposited On:29 Oct 2019 18:29
Last Modified:29 Oct 2019 18:29

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