Amplitude variability in γ Dor and δ Sct stars observed by the <i>Kepler</i> spacecraft

Guzik, Joyce A.; Kosak, Katie; Bradley, P. A.; Jackiewicz, Jason

doi:10.1017/s1743921316006128

Cited by 3 publications

(1 citation statement)

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“…Investigating Kepler δ Scuti stars, 603 stars exhibited at least one pulsation mode that varied significantly in amplitude over 4 years (Bowman et al, 2016). In more general, amplitude and/or frequency variations had been found among nearly all types of non-stochastically excited pulsators (Guzik et al, 2015). The long-term follow-up of the famous δ Scuti star, 4 CVn, showed that most pulsation modes exhibited a systematic significant period and amplitude changes on a timescale of decades (Breger et al, 2017).…”

Section: Newest Results Of the Space Era 2006-2018mentioning

confidence: 99%

An Observer's View on the Future of Asteroseismology

Paparó

2019

Front. Astron. Space Sci.

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Scientific research is a continuous process, and the speed of future progress can be estimated by the pace of finding explanations for previous research questions. In this observers based view of stellar pulsation and asteroseismology, we start with the earliest observations of variable stars and the techniques used to observe them. The earliest variable stars were large amplitude, radial pulsators but were followed by other classes of pulsating stars. As the field matured, we outline some cornerstones of research into pulsating star research with an emphasis on changes in observational techniques. Improvements from photographs, to photometry, CCDs, and space telescopes allowed researchers to separate out pulsating stars from other stars with light variations, recognize radial and nonradial pulsation courtesy of increased measurement precision, and then use nonradial pulsations to look inside the stars, which cannot be done any other way. We follow several highlighted problems to show that even with excellent space data, there still may not be quick theoretical explanations. As the result of technical changes, the structure of international organizations devoted to pulsating stars has changed, and an increasing number of conferences specialized to space missions or themes are held. Although there are still many unsolved problems, such as mode identification in non-asymptotic pulsating stars, the large amount of data with unprecedented precision provided by space missions (MOST, CoRoT, Kepler) and upcoming missions allow us to use asteroseismology to its full potential. However, the enormous flow of data will require new techniques to extract the science before the next missions. The future of asteroseismology will be successful if we learn from the past and improve with improved techniques, space missions, and a properly educated new generation.

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Section: Newest Results Of the Space Era 2006-2018mentioning

confidence: 99%

An Observer's View on the Future of Asteroseismology

Paparó

2019

Front. Astron. Space Sci.

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Exploring the unexpected: Disharmonized harmonic pulsation modes in high-amplitude δ Scuti stars

Xue,

Niu

2024

A&A

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Harmonics are a ubiquitous feature across various pulsating stars.\ They are traditionally viewed as mere replicas of the independent primary pulsation modes and have thus been excluded from asteroseismological models. Recent research, however, has uncovered a significant discrepancy: in high-amplitude delta Scuti (HADS) stars, harmonics exhibit uncorrelated variations in amplitude and frequency relative to their independent primary pulsation modes . The nature of these disharmonized harmonics is a question of critical importance. In our study we analysed five triple-mode HADS stars observed by the Transiting Exoplanet Survey Satellite (TESS) and discovered some pervasive patterns of disharmonized harmonics in both the fundamental ($f_0$) and first overtone ($f_1$) pulsation modes. Intriguingly, through an in-depth frequency interaction analysis of V1393 Cen, we identified $2f_1$ as an independent pulsation mode, distinct from $f_1$, and identified it as the progenitor of the frequency variations observed in $3f_1$, $4f_1$, $5f_1$, and $6f_1$. Similar behaviour can be found in DO CMi and GSC 06047-00749, in which $2f_1$ and $3f_1$ are the independent pulsation modes, respectively. Notably, we found an interesting pattern when decomposing the harmonics that might suggest a generation process of harmonics. These findings serve as a new window on the research of harmonics, which remains a hidden corner of contemporary asteroseismology

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Identifying low-amplitude pulsating stars through microlensing observations

Sajadian

Ignace

Neilson

2021

Monthly Notices of the Royal Astronomical Society

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One possibility for detecting low-amplitude pulsational variations is through gravitational microlensing. During a microlensing event, the temporary brightness increase leads to improvement in the signal-to-noise ratio, and thereby better detectability of pulsational signatures in light curves. We explore this possibility under two primary considerations. The first is when the standard point-source and point-lens approximation applies. In this scenario, dividing the observed light curve by the best-fitted microlensing model leads to residuals that result in pulsational features with improved uncertainties. The second is for transit events (single lens) or caustic crossing (binary lens). The point-source approximation breaks down, and residuals relative to a simple best-fitted microlensing model display more complex behavior. We employ a Monte-Carlo simulation of microlensing of pulsating variables toward the Galactic bulge for the surveys of OGLE and of KMTNet. We demonstrate that the efficiency for detecting pulsational signatures with intrinsic amplitudes of <0.25 mag during single and binary microlensing events, at differences in χ2 of Δχ2 > 350, is $\sim 50-60\%$. The maximum efficiency occurs for pulsational periods P ≃ 0.1 − 0.3 days. We also study the possibility that high-magnification microlensing events of non-radially pulsating stars (NRPs) could be misinterpreted as planetary or binary microlensing events. We conclude that small asymmetric features around lightcurve peaks due to stellar pulsations could be misdiagnosed with crossing (or passing close to) small caustic curves.

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Amplitude variability in γ Dor and δ Sct stars observed by the Kepler spacecraft

Cited by 3 publications

References 20 publications

An Observer's View on the Future of Asteroseismology

An Observer's View on the Future of Asteroseismology

Exploring the unexpected: Disharmonized harmonic pulsation modes in high-amplitude δ Scuti stars

Identifying low-amplitude pulsating stars through microlensing observations

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