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11 pages, 771 KiB

Open AccessArticle

Period Variation Rates of Four Radial Single-Mode High-Amplitude Delta Scuti Stars

by Tian-Fang Ma, Jia-Shu Niu and Hui-Fang Xue

Universe 2025, 11(3), 86; https://doi.org/10.3390/universe11030086 - 6 Mar 2025

Viewed by 675

In this work, we present a study on the long time-scale period variations of four single-mode high-amplitude delta Scuti stars (HADS) via the classical

O - C

analysis. The target HADS are (i) XX Cygni, (ii) YZ Bootis, (iii) GP Andromedae, and (iv) [...] Read more.

In this work, we present a study on the long time-scale period variations of four single-mode high-amplitude delta Scuti stars (HADS) via the classical

O - C

analysis. The target HADS are (i) XX Cygni, (ii) YZ Bootis, (iii) GP Andromedae, and (iv) ZZ Microscopii. The newly determined times of maximum light came from the Transiting Exoplanet Survey Satellite (TESS), American Association of Variable Star Observers (AAVSO), and Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne (BAV) projects. Together with the times of maximum light obtained in the historical literature, the

O - C

analysis was performed on these HADS, in which we obtained the linear period variation rates

\dot{P} / P

(9.2 \pm 0.2) \times 10^{- 9} {yr}^{- 1}

(3.2 \pm 0.2) \times 10^{- 9} {yr}^{- 1}

(4.22 \pm 0.03) \times 10^{- 8} {yr}^{- 1}

, and

(- 2.06 \pm 0.02) \times 10^{- 8} {yr}^{- 1}

, respectively. Based on these results and some earlier research, we also discuss the evolutionary stages and the mechanisms of the period variation of these four HADS. Full article

(This article belongs to the Special Issue Variable Stars in the 21st Century: From Microvariability to Megavariability)

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15 pages, 1374 KiB

Open AccessArticle

Mass-Accreting Pulsating Components of Algols

by David Mkrtichian, Khemsinan Gunsriviwat, Holger Lehmann, Chris Engelbrecht, Andrew Tkachenko and Victor Nazarenko

Galaxies 2022, 10(5), 97; https://doi.org/10.3390/galaxies10050097 - 16 Sep 2022

Cited by 4 | Viewed by 2774

Abstract

We present a review of the latest results of studies of the class of mass-accreting pulsating components of semi-detached eclipsing binaries known as oEA stars. The application of the techniques of asteroseismology to this class of stars unlocks new pathways for gaining a deeper understanding of the short-term evolution and magnetic activity of binary stars. We report the discovery of 49 new pulsating components of eclipsing binaries, based on data from NASA’s TESS space telescope. Recent observational results on the pulsation characteristics of these stars are summarized. The effects of the interaction of the magnetic and spot activity of the Roche-lobe-filling component of a system with the pulsations of the mass-accreting component are discussed. Full article

(This article belongs to the Special Issue What’s New under the Binary Suns)

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24 pages, 12825 KiB

Open AccessArticle

Asteroseismic Analysis of δ Scuti Components of Binary Systems: The Case of KIC 8504570

by Alexios Liakos and Panagiotis Niarchos

Galaxies 2020, 8(4), 75; https://doi.org/10.3390/galaxies8040075 - 28 Oct 2020

Cited by 5 | Viewed by 3155

Abstract

The present work concerns the Asteroseismology of the

K e p l e r

The present work concerns the Asteroseismology of the

K e p l e r

-detached eclipsing binary KIC 8504570. Particularly, it focuses on the pulsational behaviour of the oscillating component of this system and the estimation of its physical parameters in order to enrich the so far poor sample of systems of this kind. Using spectroscopic observations, the spectral type of the primary component was determined and used to create accurate light curve models and estimate its absolute parameters. The light curve residuals were subsequently analysed using Fourier transformation techniques to obtain the pulsation models. Theoretical models of

δ

Scuti stars were employed to identify the oscillation modes of the six detected independent frequencies of the pulsator. In addition, more than 385 combination frequencies were also detected. The absolute and the pulsational properties of the

δ

Scuti star of this system are discussed and compared with all the currently known similar cases. Moreover, using a recent(empirical) luminosity–pulsation period relationship for

δ

Scuti stars, the distance of the system was estimated. Full article

(This article belongs to the Special Issue Astrophysics of Eclipsing Binaries in the Era of Space-Borne Telescopes)

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