Asteroseismology of hot subdwarf B stars observed with TESS: discovery of two new gravity mode pulsating stars
Murat Uzundag,
Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile and European Southern Observatory, Alonso de Cordova 3107, Santiago, Chile. Corresponding author:
muratuzundag.astro@gmail.com
Roberto Silvotti,
INAF-Osservatorio Astrofisico di Torino, strada dell’Osservatorio 20, 10025 Pino Torinese, Italy
Andrzej S. Baran,
ARDASTELLA Research Group and Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
Maja Vučković,
Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile
Sumanta K. Sahoo,
ARDASTELLA Research Group and Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warsaw, Poland
Mike Reed,
Department of Physics, Astronomy and Materials Science, Missouri State University, 901 S, National, Springfield, MO 65897, USA
Abstract
TIC 033834484 and TIC 309658435 are long-period pulsating subdwarf B stars, 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 µHz (2 500 s) to ∼400 µHz (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 (ΔPl=1), which allows us to identify the modes. Frequency multiplets provide a rotation period of ∼64 d for TIC 033834484. From follow-up ground-based spectroscopy, we find that TIC 033834484 has an effective temperature of 24 210 K (140), a surface gravity of log g/cms-2 = 5.28 (03) and TIC 309658435 has an effective temperature of 25 910 K (150), a surface gravity of log g/cms-2 = 5.48 (03).
Keywords : asteroseismology, stars: oscillations (including pulsations), stars: interiors, stars: evolution, stars: horizontal-branch, stars: subdwarfs, stars: individual: TIC 033834484, TIC 309658435
To cite this article
Murat Uzundag, Roberto Silvotti, Andrzej S. Baran, Maja Vučković, Péter Németh, Sumanta K. Sahoo & Mike Reed, «Asteroseismology of hot subdwarf B stars observed with TESS: discovery of two new gravity mode pulsating stars», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 92 - Année 2023, Numéro 2 - Proceedings of the 10th Meeting on Hot Subdwarfs and Related Objects, 117-125 URL : http://popups.ulg.be/0037-9565/index.php?id=11294.
