TESS photometry of the eclipsing δ Scuti star AI Hydrae

Jae Woo Lee*, Kyeongsoo Hong, Martti H. Kristiansen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


AI Hya has been known as an eclipsing binary with a monoperiodic δ Sct pulsator. We present the results from its TESS (Transiting Exoplanet Survey Satellite) photometry observed during Sector 7. Including our five minimum epochs, the eclipse timing diagram displays the apsidal motion with a rate of ω˙=0.075±0.031degyr−1⁠, which corresponds to an apsidal period of U=4800±2000yr. The binary star model represents that the smaller, less massive primary component is 427K hotter than the pulsating secondary, and our distance of 612±36pc is in good agreement with the Gaia distance of 644±26pc. We subtracted the binary effects from the observed TESS data and applied a multifrequency analysis to these residuals. The result reveals that AI Hya is multiperiodic in its pulsation. Of 14 signals detected, four (⁠f1⁠, f2⁠, f3⁠, f6⁠) may be considered independent pulsation frequencies. The period ratios of Ppul/Porb=0.012–0.021 and the pulsation constants of Q=0.30–0.52 d correspond to δ Sct pulsations in binaries. We found that the secondary component of AI Hya pulsates in both radial fundamental F modes (⁠f2 and f3⁠) and non-radial g1 modes with a low degree of ℓ=2 (⁠f1 and f6⁠).
Original languageEnglish
Article number37
JournalPublications of the Astronomical Society of Japan
Issue number3
Number of pages9
Publication statusPublished - 2020


  • Asteroseismology
  • Binaries: eclipsing
  • Stars: fundamental parameters
  • Stars: individual (AI Hydrae)
  • Stars: oscillations

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