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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

(Volume 92 - Année 2023 — Numéro 2 - Proceedings of the 10th Meeting on Hot Subdwarfs and Related Objects)
DOI: 10.25518/0037-9565.11294
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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.

About: 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

About: Roberto Silvotti

INAF-Osservatorio Astrofisico di Torino, strada dell’Osservatorio 20, 10025 Pino Torinese, Italy

About: Andrzej S. Baran

ARDASTELLA Research Group and Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

About: Maja Vučković

Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile

About: Péter Németh

Astroserver.org, Főtér 1, 8533 Malomsok, Hungary

About: Sumanta K. Sahoo

ARDASTELLA Research Group and Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warsaw, Poland

About: Mike Reed

Department of Physics, Astronomy and Materials Science, Missouri State University, 901 S, National, Springfield, MO 65897, USA