Turbulent convection and pulsation stability of stars – II. Theoretical instability strip for<i>δ</i>Scuti and<i>γ</i>Doradus stars

Xiong, Dongbin; Deng, Licai; Zhang, C.; Wang, Ke

doi:10.1093/mnras/stw047

Cited by 114 publications

(125 citation statements)

References 32 publications

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…The dashed (green) region in the top left corner is the cool end of the SPB instability strip. The red and blue edges of the γ Dor instability strip calculated by Dupret et al (2004) are shown as solid lines, while those calculated by Xiong et al (2016) are shown by the dashed lines. The dotted line is the zero-age main sequence for solar composition (from Bertelli et al 2008).…”

Section: Maia Variablesmentioning

confidence: 99%

The hot γ Doradus and Maia stars

Balona

Engelbrecht

Joshi

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

The hot γ Doradus stars have multiple low frequencies characteristic of γ Dor or SPB variables, but are located between the red edge of the SPB and the blue edge of the γ Dor instability strips where all low-frequency modes are stable in current models of these stars. Though δ Sct stars also have low frequencies, there is no sign of high frequencies in hot γ Dor stars. We obtained spectra to refine the locations of some of these stars in the H-R diagram and conclude that these are, indeed, anomalous pulsating stars. The Maia variables have multiple high frequencies characteristic of β Cep and δ Sct stars, but lie between the red edge of the β Cep and the blue edge of the δ Sct instability strips. We compile a list of all Maia candidates and obtain spectra of two of these stars. Again, it seems likely that these are anomalous pulsating stars which are currently not understood.

show abstract

Section: Maia Variablesmentioning

confidence: 99%

The hot γ Doradus and Maia stars

Balona

Engelbrecht

Joshi

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…Guzik et al (2000); Dupret et al (2005) reported that the g-mode pulsations are excited by the con-vective flux blocking mechanism that operates at the base of the envelope convection zone. Xiong et al (2016) found that the radiative κ mechanism plays a major role in warm γ Dor stars while the coupling between convection and oscillations is dominant in cool stars. Turbulent thermal convection is a damping mechanism that gives rise to the red edge of the instability strip.…”

Section: Introductionmentioning

confidence: 99%

Gravity-mode period spacings and near-core rotation rates of 611 γ Doradus stars with Kepler

Reeth

Bedding

et al. 2019

Monthly Notices of the Royal Astronomical Society

115

View full text Add to dashboard Cite

We report our survey of γ Dor stars from the 4-yr Kepler mission. These stars pulsate mainly in g modes and r modes, showing period-spacing patterns in the amplitude spectra. The period-spacing patterns are sensitive to the chemical composition gradients and the near-core rotation, hence they are essential for understanding the stellar interior. We identified period-spacing patterns in 611 γ Dor stars. Almost every star pulsates in dipole g modes, while about 30% of stars also show clear patterns for quadrupole g modes and 16% of stars present r mode patterns. We measure periods, period spacings, and the gradient of the period spacings. These three observables guide the mode identifications and can be used to estimate the near-core rotation rate. We find many stars are hotter and show longer period-spacing patterns than theory. Using the Traditional Approximation of Rotation (TAR), we inferred the asymptotic spacings, the near-core rotation rates, and the radial orders of the g and r modes. Most stars have a near-core rotation rate around 1 d −1 and an asymptotic spacing around 4000 s. We also find that many stars rotate more slowly than predicted by theory for unclear reasons. 11 stars show rotational splittings with fast rotation rates. We compared the observed slope-rotation relation with the theory and find a large spread. We detected rotational modulations in 58 stars and used them to derive the core-tosurface rotation ratios. The interiors rotate faster than the cores in most stars, but by no more than 5%.

show abstract

“…In general, the observed frequency range of δ Sct stars matches the theoretical range of unstable modes calculated from stellar models with current opacities (Pamyatnykh2003; Casas et al 2009;Zwintz et al 2014). For γ Dor stars, the comparison between observation and theory is by far mostly restricted to the instability strip (Dupret et al 2004;Bouabid et al 2013;Xiong et al 2016), not the frequency range of unstable modes of individual stars (see Maceroni 2014 for an exception). This is, again, due to the difficulty in modeling the interaction between the convection and oscillations.…”

Section: Introductionmentioning

confidence: 99%

KIC 4142768: An Evolved Gamma Doradus/Delta Scuti Hybrid Pulsating Eclipsing Binary with Tidally Excited Oscillations

Guo

Fuller

Shporer

et al. 2019

ApJ

View full text Add to dashboard Cite

We present the characterization of KIC 4142768, an eclipsing binary with two evolved A-type stars in an eccentric orbit with a period of 14 days. We measure the fundamental parameters of the two components (M 1 = 2.05M , R 1 = 2.96R and M 2 = 2.05M , R 2 = 2.51R ) by combining Kepler photometry and spectra from Keck HIRES. The measured surface rotation rates are only one-fifth of the pseudo-synchronous rate of the eccentric orbit. Fourier spectrum of the light curve reveals hybrid pulsations of δ Scuti and γ Doradus type, with pulsation frequencies at about 15 − 18 day −1 for p modes and about 0.2 − 1.2 day −1 for low-frequency g modes. Some of the g modes are exact orbital harmonics and are likely tidally excited. Their pulsation amplitudes and phases both agree with predictions from the linear tidal theory for l = 2, m = 2 prograde modes. We examine the period spacing patterns in the free oscillating g modes and identify them mostly as prograde sectoral dipole modes. The unstable frequency range and frequency spacing of p modes and the inferred asymptotic g-mode period arXiv:1909.03908v1 [astro-ph.SR] 9 Sep 2019 -2spacings both agree with the stellar model for the primary star evolved to a late stage of the main sequence. The inferred rotation rate of the convective core boundary is very slow, similar to the small surface rotation rate inferred from the spectroscopy. The measured surface and near-core rotation rates provide constraints for testing the mechanism of angular momentum transfer and tidal synchronization in evolved eccentric binary star systems.

show abstract

Turbulent convection and pulsation stability of stars – II. Theoretical instability strip forδScuti andγDoradus stars

Cited by 114 publications

References 32 publications

The hot γ Doradus and Maia stars

The hot γ Doradus and Maia stars

Gravity-mode period spacings and near-core rotation rates of 611 γ Doradus stars with Kepler

KIC 4142768: An Evolved Gamma Doradus/Delta Scuti Hybrid Pulsating Eclipsing Binary with Tidally Excited Oscillations

Contact Info

Product

Resources

About