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arXiv · 2212.02950

Asteroseismology of hot subdwarf B stars observed with TESS: discovery of two new gravity mode pulsating stars

Murat Uzundag·Roberto Silvotti·Andrzej S. Baran·Maja Vuckovic·Péter Nemeth·Sumanta K. Sahoo·Mike Reed
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Abstract

TIC033834484 and TIC309658435 are long-period pulsating subdwarf B star, which were observed extensively (675 and 621 days, respectively) by the Transiting Exoplanet Survey Satellite (TESS). The high-precision photometric light curve reveals the presence of more than 40 pulsation modes including both stars. All the oscillation frequencies that we found are associated with gravity (g)-mode pulsations, with frequencies spanning from 80 $\mu$Hz (2 500 s) to 400 $\mu$Hz (12 000 s). We utilize the asteroseismic tools including asymptotic period spacings and rotational frequency multiplets in order to identify the pulsational modes. We found dipole (l = 1) mode sequences for both targets and calculate the mean period spacing of dipole modes ($\Delta P_{l=1}$), which allows us to identify the modes. Frequency multiplets provide a rotation period of about 64 d for TIC033834484. From follow-up ground-based spectroscopy, we find that TIC\,033834484 has an effective temperature of 24 210 K (140), a surface gravity of logg = 5.28 (03) and TIC309658435 has an effective temperature of 25 910 K (150), a surface gravity of logg = 5.48 (03).

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Murat Uzundag, Roberto Silvotti, Andrzej S. Baran, Maja Vuckovic, Péter Nemeth, Sumanta K. Sahoo, Mike Reed. 2022-12-06. Asteroseismology of hot subdwarf B stars observed with TESS: discovery of two new gravity mode pulsating stars. https://arxiv.org/abs/2212.02950

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