γ Doradus Stars: Defining a New Class of Pulsating Variables

Kaye, A. B.; Handler, G.; Krisciunas, K.; Poretti, E.; Zerbi, F. M.

doi:10.1086/316399

Cited by 250 publications

(202 citation statements)

References 18 publications

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“…The g Doradus class varies via g-mode pulsations with one or more periods between 0.4 and 3 days and amplitudes of . These stars are found among spectral types V Շ 0.1 A7-F5 and luminosity classes V-IV, placing them on the H-R diagram near the red edge of the d Scuti instability strip (Kaye et al 1999). The typical amplitudes of g Doradus stars are detectable for the bright stars in our survey and should show periodic variations.…”

Section: Pulsating Variablesmentioning

confidence: 55%

Stellar Variability in a Survey of Field Stars

Everett

Howell

Belle

et al. 2002

PUBL ASTRON SOC PAC

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ABSTRACT. We present results from a 5 night wide-field time-series photometric survey that detects variable field stars. We find that the fraction of stars whose light curves show variations depends on color and magnitude, reaching 17% for the brightest stars in this survey ( ) for which the photometric precision is best. The V ∼ 14 fraction of stars found to be variable is relatively high at colors bluer than the Sun and relatively low at colors similar to the Sun and increases again for stars redder than the Sun. We present light curves for a sample of the pulsating and eclipsing variables. Most of the stars identified as pulsating variables have low amplitudes ( ), relatively blue colors, and multiple periods. There are 13 stars we identify as either SX DV p 0.01-0.05 Phoenicis or d Scuti stars. These classes represent a significant contribution to the total number of blue variables found in this survey. Another 17 stars are identified as eclipsing variables, which have a wide range in color, magnitude, and amplitude. Two variable giants are observed, and both show night-to-night ∼1% variations. We present data for 222 variables in total, most of which are not classified. Implications of surveys for stellar variability and interferometry are briefly discussed.

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Section: Pulsating Variablesmentioning

confidence: 55%

Stellar Variability in a Survey of Field Stars

Everett

Howell

Belle

et al. 2002

PUBL ASTRON SOC PAC

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“…Handler 1999;Kaye et al 1999;Cuypers et al 2009), space-based observations revealed dozens to hundreds of oscillation frequencies for each star. This in principle should allow the detection of period spacing patterns.…”

Section: The Methodologymentioning

confidence: 99%

Detecting non-uniform period spacings in theKeplerphotometry ofγDoradus stars: methodology and case studies

Reeth

Tkachenko

Aerts

et al. 2015

A&A

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Context. The analysis of stellar oscillations is one of the most reliable ways to probe stellar interiors. Recent space missions such as Kepler have provided us with an opportunity to study these oscillations with unprecedented detail. For many multi-periodic pulsators such as γ Doradus stars, this led to the detection of dozens to hundreds of oscillation frequencies that could not be found from groundbased observations. Aims. We aim to detect non-uniform period spacings in the Fourier spectra of a sample of γ Doradus stars observed by Kepler. Such detection is complicated by both the large number of significant frequencies in the space photometry and by overlapping nonequidistant rotationally split multiplets. Methods. Guided by theoretical properties of gravity-mode oscillation of γ Doradus stars, we developed a period-spacing detection method and applied it to Kepler observations of a few stars, after having tested the performance from simulations. Results. The application of the technique resulted in the clear detection of non-uniform period spacing series for three out of the five treated Kepler targets. Disadvantages of the technique are also discussed, and include the disability to distinguish between different values of the spherical degree and azimuthal order of the oscillation modes without additional theoretical modelling. Conclusions. Despite the shortcomings, the method is shown to allow solid detections of period spacings for γ Doradus stars, which will allow future asteroseismic analyses of these stars.

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“…They cover the transition region between low-mass stars possessing radiative cores and convective envelopes to high-mass stars which have convective cores and radiative envelopes. γ Doradus pulsators exhibit non-radial gravity (g) and / or gravito-inertial modes, with observed pulsation periods between 0.3 and 3 days (Kaye et al 1999), that are excited by the convective flux blocking mechanism at the bottom of the con-vective envelope (Guzik et al 2000;Dupret et al 2005). These pulsations are most sensitive to the characteristics of the deep stellar interior.…”

Section: Introductionmentioning

confidence: 99%

Constraining the near-core rotation of theγDoradus star 43 Cygni using BRITE-Constellation data

Zwintz

Reeth

Tkachenko

et al. 2017

A&A

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Context. Photometric time series of the γ Doradus star 43 Cyg obtained with the BRITE-Constellation nano-satellites allow us to study its pulsational properties in detail and to constrain its interior structure. Aims. We aim to find a g-mode period spacing pattern that allows us to determine the near-core rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric parameters and chemical composition.Methods. We conducted a frequency analysis using the 156-days long data set obtained with the BRITE-Toronto satellite and employed a suite of MESA/GYRE models to derive the mode identification, asymptotic period spacing and near-core rotation rate. We also used high-resolution, high signal-to-noise ratio spectroscopic data obtained at the 1.2m Mercator telescope with the HER-MES spectrograph to redetermine the fundamental atmospheric parameters and chemical composition of 43 Cyg using the software Spectroscopy Made Easy (SME). Results. We detected 43 intrinsic pulsation frequencies and identified 18 of them to be part of a period spacing pattern consisting of prograde dipole modes with an asymptotic period spacing ∆Π l=1 of 2970 +700 −570 s. The near-core rotation rate was determined to be f rot = 0.56 +0.12 −0.14 d −1 . The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature, T eff , of 7150 ± 150 K, a log g of 4.2 ± 0.6 dex and a projected rotational velocity, υ sin i, of 44 ± 4 km s −1 . Conclusions. The morphology of the observed period spacing patterns shows indications of the presence of a significant chemical gradient in the stellar interior.

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γ Doradus Stars: Defining a New Class of Pulsating Variables

Cited by 250 publications

References 18 publications

Stellar Variability in a Survey of Field Stars

Stellar Variability in a Survey of Field Stars

Detecting non-uniform period spacings in theKeplerphotometry ofγDoradus stars: methodology and case studies

Constraining the near-core rotation of theγDoradus star 43 Cygni using BRITE-Constellation data

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