Volume 655, November 2021
|Number of page(s)||7|
|Section||Stellar structure and evolution|
|Published online||19 November 2021|
TIC 308396022: δ Scuti–γ Doradus hybrid with large-amplitude radial fundamental mode and regular g-mode period spacing
Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi’an Jiaotong University, 710049 Xi’an, PR China
2 IRAP, Université de Toulouse, CNRS, CNES, UPS, Toulouse, France
3 Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, Camperdown, NSW 2006, Australia
4 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
5 Space Telescope Science Institute in Baltimore, Baltimore, MD, USA
Accepted: 30 September 2021
We analyse the pulsating behaviour of TIC 308396022, based on observations by the TESS mission. The star is a high-amplitude δ Sct star that shows a very rich amplitude spectrum using the 3-yr light curve. Among these frequencies, the strongest peak of f1 = 13.20362567(12) d−1 is identified as the radial fundamental mode, and we also find the first and second overtones (f2 and f3). In the low-frequency range (< 2.5 d−1), 22 peaks are identified as gravity modes, which show a regular period spacing of about 2460 s and have an angular degree of l = 1. The period spacing pattern does not show a significant downward trend, suggesting the star is rotating slowly. We note that this is a δ Sct–γ Dor hybrid star containing a high-amplitude radial fundamental mode and a regular g-mode period spacing pattern. With the O − C analysis, we find the star shows a significant time delay, implying that the star has a companion and it is likely to be a white dwarf. The history of possible mass transfer provides a great opportunity for testing the current theories of binary evolution, mass transfer, and pulsation.
Key words: stars: oscillations / stars: variables: δ Scuti / stars: individual: TIC 308396022
© ESO 2021
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