Non-adiabatic pulsations in ESTER models

Reese, D. R.; Dupret, Marc‐Antoine; Rieutord, M.

doi:10.1051/epjconf/201716002007

Cited by 6 publications

(11 citation statements)

References 28 publications

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“…In this context, it may be remarked that the amplitude of the observed line profile changes peaks towards the line center whereas models often predict larger amplitudes in the wings (e.g. Reese et al 2017) or at least a flatter amplitude distribution across the profile than observed in π Aqr. Certainly, specific asteroseismic modelling of π Aqr is now required, but this goes beyond the scope of this paper.…”

Section: π Aqrmentioning

confidence: 99%

“…For π Aqr, using the stellar parameters of Bjorkman et al (2002), the rotational period amounts to 1.2 d. Since the pulsation frequency detected in spectroscopic and photometric data is ∼12 d −1 , the ratio between pulsation and rotation frequencies is about 14, which is quite high. General asteroseismic modelling applicable to fast rotators begins to be performed, with the first steps towards similar diagnostics as in Telting & Schrijvers (1997) being recently made (Reese et al 2017, -see also pioneering models accounting for first-order effects of rotation in Townsend 1997; Maintz et al 2003). In this context, it may be remarked that the amplitude of the observed line profile changes peaks towards the line center whereas models often predict larger amplitudes in the wings (e.g.…”

Section: π Aqrmentioning

confidence: 99%

See 1 more Smart Citation

Let there be more variability in two γ Cas stars

Nazé

Pigulski

Rauw

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We investigate the short-term optical variability of two γ Cas analogs, π Aqr and BZ Cru, thanks to intensive ground-based spectroscopic and space-borne photometric monitorings. For both stars, low-amplitude (mmag) coherent photometric variability is detected. The associated signals display long-term amplitude variations, as in other Be stars. However, these signals appear at high frequencies, especially in π Aqr, indicating p-modes with a high degree l, a quite unusual feature amongst Be stars. While BZ Cru presents only low-level spectral variability, without clear periodicity, this is not the case of π Aqr. In this star, the dominant photometric frequencies, near ∼12 d −1 , are confirmed spectroscopically in separate monitorings taken during very different disk activity levels ; the spectroscopic analysis suggests a probable tesseral nature for the mode.

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Section: π Aqrmentioning

confidence: 99%

Section: π Aqrmentioning

confidence: 99%

Let there be more variability in two γ Cas stars

Nazé

Pigulski

Rauw

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…HD220811, which is quite similar to Altair as far as T eff and Vsini are concerned, also shows a similar number of frequencies. This point is reminiscent of the theoretical (preliminary) result of Reese et al (2017), which shows that as the rotation rate increases, mode excitation is less and less efficient. In other words, rotation tends to stabilise modes otherwise destabilised by the κ-mechanism.…”

Section: Discussionmentioning

confidence: 64%

“…The probable similarity of Altair and HD220811 as far as their oscillation spectrum and spectral type are concerned, together with their very fast rotation (V eq ∼ 300 km s −1 ), may illustrate the result of Reese et al (2017) that fast rotation Notes. The six starred frequencies are new and complete those detected by Buzasi et al (2005).…”

Section: Hd220811: Potential Sister Of Altairmentioning

confidence: 93%

Seismology of Altair with MOST

Dizès

Rieutord

Charpinet

2021

A&A

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Context. Altair is the fastest rotating star at less than 10 parsecs from the Sun. Its precise modelling is a landmark for our understanding of stellar evolution with fast rotation, and all observational constraints are most welcome to better determine the fundamental parameters of this star. Aims. We wish to improve the seismic spectrum of Altair and confirm the δ-Scuti nature of this star. Methods. We used the photometric data collected by the Microvariability and Oscillations of STars (MOST) satellite in the form of a series of Fabry images to derive Altair light curves at four epochs, namely in 2007, 2011, 2012, and 2013. Results. We first confirm the presence of δ-Scuti oscillations in the light curves of Altair. We extend the precision of some eigenfrequencies and add new ones to the spectrum of Altair, which now has 15 detected eigenmodes. The rotation period, which is expected at ∼7h46min from models reproducing interferometric data, seems to appear in the 2012 data set, but it still needs confirmation. Finally, Altair modal oscillations show noticeable amplitude variations on a timescale of 10–15 days, which may be the signature of a coupling between oscillations and thermal convection in the layer where the kappa-mechanism is operating. Conclusions. The Altair oscillation spectrum does not contain a large number of excited eigenmodes, which is similar to the fast rotating star HD220811. This supports the idea that fast rotation hinders the excitation of eigenmodes as already pointed out by theoretical investigations.

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“…The probable similarity of Altair and HD220811 as far as their oscillation spectrum and spectral type are concerned, together with their very fast rotation (V eq ∼ 300 km/s), may illustrate the result of Reese et al (2017) that fast rotation reduces the number of excited modes in a star. The parallel study of these two stars, and others with the same features, will be very useful to better appreciate all the effects of rotation.…”

Section: Hd220811: Potential Sister Of Altairmentioning

confidence: 96%

Seismology of Altair with MOST

Dizès,

Rieutord,

Charpinet

et al. 2021

Preprint

Self Cite

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Context. Altair is the fastest rotating star at less than 10 parsecs from the Sun. Its precise modelling is a landmark for our understanding of stellar evolution with fast rotation, and all observational constraints are most welcome to better determine the fundamental parameters of this star. Aims. We wish to improve the seismic spectrum of Altair and confirm the δ-Scuti nature of this star. Methods. We used the photometric data collected by the Microvariability and Oscillations of STars (MOST) satellite in the form of a series of Fabry images to derive Altair light curves at four epochs, namely in 2007, 2011, 2012, and 2013. Results. We first confirm the presence of δ-Scuti oscillations in the light curves of Altair. We extend the precision of some eigenfrequencies and add new ones to the spectrum of Altair, which now has 15 detected eigenmodes. The rotation period, which is expected at ∼7h46min from models reproducing interferometric data, seems to appear in the 2012 data set, but it still needs confirmation. Finally, Altair modal oscillations show noticeable amplitude variations on a timescale of 10 to 15 days, which may be the signature of a coupling between oscillations and thermal convection in the layer where the kappa-mechanism is operating. Conclusions. The Altair oscillation spectrum does not contain a large number of excited eigenmodes, which is similar to the fast rotating star HD220811. This supports the idea that fast rotation hinders the excitation of eigenmodes as already pointed out by theoretical investigations.

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Non-adiabatic pulsations in ESTER models

Cited by 6 publications

References 28 publications

Let there be more variability in two γ Cas stars

Let there be more variability in two γ Cas stars

Seismology of Altair with MOST

Seismology of Altair with MOST

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