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):46. pp. 1-14. ISSN 0004-637X


Abstract

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 (M 1=2.05 M ,R 1=2.96 R and M 2=2.05 M,R 2=2.51 R) 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.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 15 Jul 2022 02:43
Last Modified: 17 Jul 2022 23:52
Uncontrolled Keywords: Stellar oscillations; Asteroseismology; Binary stars; Eclipsing binary stars; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-4357/ab41f6
URI: http://eprints.usq.edu.au/id/eprint/47878

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