A window into δ Sct stellar interiors: understanding the eclipsing binary system TT Hor

Streamer, Margaret and Ireland, Michael J. and Murphy, Simon J. and Bento, Joao (2018) A window into δ Sct stellar interiors: understanding the eclipsing binary system TT Hor. Monthly Notices of the Royal Astronomical Society, 480 (1). pp. 1372-1383. ISSN 0035-8711

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The semi-detached eclipsing binary system TT Hor has a δ Sct primary component (accretor) accreting mass from the secondary star (donor). We fit an eclipsing binary model from V, B, and I photometry combined with spectroscopy using PHOEBE. Radial velocity variations of the centre of mass of TT Hor AB over two years suggest the presence of a wide companion, consistent with a Kozai–Lidov resonance formation process for TT Hor AB. Evolutionary models computed with MESA give the initial mass of the donor as ≈1.6 M⊙ and that of the accretor as ≈1.3 M⊙. The initial binary orbit has a similar initial separation to the currently observed separation of 11.4 R⊙. Mass transfer commences at an age of 2.5 Gyr when the donor is a subgiant. We model the accretor as a tidally locked 2.2 ± 0.2 M⊙ δ Sct pulsator which has accreted ≈0.9 M⊙ of slightly He-enriched material (mean ΔY < 0.01) from the donor over the last 90 Myr. The best fit from all measured parameters and evolutionary states is for a system metallicity of [M/H] = 0.15. A pulsation model of the primary gives a self-consistent set of modes. Our observed oscillation frequencies match to within 0.3 per cent and the system parameters within uncertainties. However, we cannot claim that our identified modes are definitive, and suggest follow-up time-series spectroscopy at high resolution in order to verify our identified modes. With the higher signal-to-noise ratio and continuous observations with TESS, more reliable mode identification due to frequency and amplitude changes during the eclipse is likely.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 27 Apr 2022 04:51
Last Modified: 28 Apr 2022 04:14
Uncontrolled Keywords: Asteroseismology; Binaries: eclipsing; Stars: variables: δ Scuti; 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/10.1093/mnras/sty1881
URI: http://eprints.usq.edu.au/id/eprint/47965

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