Pulsational properties of ten new slowly pulsating B stars

Abstract

Context. Slowly pulsating B (SPB) stars are upper main-sequence multi-periodic pulsators that show non-radial g-mode oscillations driven by the κ mechanism acting on the iron bump. These multi-periodic pulsators have great asteroseismic potential and can be employed for the calibration of stellar structure and evolution models of massive stars. Aims. We collected a sample of ten hitherto unidentified SPB stars with the aim of describing their pulsational properties and identifying pulsational modes. Methods. Photometric time series data from various surveys were collected and analyzed using diverse frequency search algorithms. We calculated astrophysical parameters and investigated the location of our sample stars in the log T eff versus log L/L diagram. Current pulsational models were calculated and used for the identification of pulsational modes in our sample stars. An extensive grid of stellar models along with their g-mode eigenfrequencies was calculated and subsequently cross-matched with the observed pulsational frequencies. The best-fit models were then used in an attempt to constrain stellar parameters such as mass, age, metallicity, and convective overshoot. Results. We present detected frequencies, corresponding g-mode identifications, and the masses and ages of the stellar models producing the best frequency cross-matches. We partially succeeded in constraining stellar parameters, in particular concerning mass and age. Where applicable, rotation periods have been derived from the spacing of triplet component frequencies. No evolved SPB stars are present in our sample. We identify two candidate high-metallicity objects (HD 86424 and HD 163285), one young SPB star (HD 36999), and two candidate young SPB stars (HD 61712 and HD 61076). Conclusions. We demonstrate the feasibility of using ground-based observations to perform basic asteroseismological analyses of SPB stars. Our results significantly enlarge the sample of known SPB stars with reliable pulsational mode identifications, which provides important input parameters for modeling attempts aiming to investigate the internal processes at work in upper main-sequence stars.

On the Diversity of Mixing and Helium Core Masses of B-type Dwarfs from Gravity-mode Asteroseismology

“…The SPB stars have masses in the range 3-10 M e and oscillate in gravity (g) modes, where gravity acts as the dominant restoring force for the oscillations (Aerts et al 2010). Until recently, the extent of the CBM region had been estimated for 19 SPB stars (Degroote et al 2010;Moravveji et al 2015Moravveji et al , 2016Szewczuk & Daszyńska-Daszkiewicz 2015Buysschaert et al 2018;Johnston et al 2019b;Moździerski et al 2019;Wu & Li 2019;Fedurco et al 2020;Wu et al 2020;Michielsen et al 2021;Szewczuk et al 2022), and the amount of envelope mixing determined for four of them (Moravveji et al 2015(Moravveji et al , 2016Wu & Li 2019;Wu et al 2020). For only two of the stars were different shapes of the CMB mixing tested against the observations (Moravveji et al 2015(Moravveji et al , 2016Michielsen et al 2021), while Michielsen et al (2021) tested the temperature gradient within the CMB region for one SPB star.…”

Outbursts and stellar properties of the classical Be star HD 6226

“…Our results on the spectroscopic time series are indeed consistent with the mode calculations of Miglio et al (2007a) for this star being a SPB star with an =1, 2, or 3 mode. While our spectroscopic data do not directly show any additional modes, it has been well established that these stars often show multiple pulsational modes (see recent analysis of Fedurco et al 2020), which could include the two photometric frequencies we discussed in Section 4.…”

A comparison of the dynamical and model-derived parameters of the pulsating eclipsing binary KIC 9850387

“…This has been demonstrated by a number of observational studies of g-mode pulsators (e.g. Moravveji et al 2015Moravveji et al , 2016Buysschaert et al 2018;Walczak et al 2019;Wu & Li 2019;Fedurco et al 2020).…”