The universal red-giant oscillation pattern

Mosser, B.; Belkacem, K.; Goupil, M. J.; Michel, E.; Elsworth, Y.; Barban, C.; Kallinger, T.; Hekker, S.; Deridder, J.; Samadi, R.; Baudin, F.; Pinheiro, F. J. G.; Auvergne, M.; Baglin, A.; Catala, C.

doi:10.1051/0004-6361/201015440

Cited by 171 publications

(243 citation statements)

References 26 publications

(37 reference statements)

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“…This curvature, always with the same concavity sign, is particularly visible in red giant oscillations (e.g., Mosser et al 2011;Kallinger et al 2012), which show solar-like oscillations at low radial order (e.g., De Ridder et al 2009;Bedding et al 2010a). Figure 1 shows a typical example of the non-negligible curvature in the échelle diagram of a main-sequence star with many radial orders.…”

Section: The Asymptotic Expansion Used In Practicementioning

confidence: 89%

Asymptotic and measured large frequency separations

Mosser¹,

Michel²,

Belkacem³

et al. 2013

A&A

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182

303

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Context. With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available and has led to a variety of work. So-called global oscillation parameters are inferred to characterize the large sets of stars, perform ensemble asteroseismology, and derive scaling relations. The mean large separation is such a key parameter, easily deduced from the radial-frequency differences in the observed oscillation spectrum and closely related to the mean stellar density. It is therefore crucial to measure it with the highest accuracy in order to obtain the most precise asteroseismic indices. Aims. As the conditions of measurement of the large separation do not coincide with its theoretical definition, we revisit the asymptotic expressions used for analyzing the observed oscillation spectra. Then, we examine the consequence of the difference between the observed and asymptotic values of the mean large separation. Methods. The analysis is focused on radial modes. We use series of radial-mode frequencies in published analyses of stars with solarlike oscillations to compare the asymptotic and observational values of the large separation. This comparison relies on the proper use of the second-order asymptotic expansion. Results. We propose a simple formulation to correct the observed value of the large separation and then derive its asymptotic counterpart. The measurement of the curvature of the radial ridges in the échelle diagram provides the correcting factor. We prove that, apart from glitches due to stellar structure discontinuities, the asymptotic expansion is valid from main-sequence stars to red giants. Our model shows that the asymptotic offset is close to 1/4, as in the theoretical development, for low-mass, main-sequence stars, subgiants and red giants. Conclusions. High-quality solar-like oscillation spectra derived from precise photometric measurements are definitely better described with the second-order asymptotic expansion. The second-order term is responsible for the curvature observed in the échelle diagrams used for analyzing the oscillation spectra, and this curvature is responsible for the difference between the observed and asymptotic values of the large separation. Taking it into account yields a revision of the scaling relations, which provides more accurate asteroseismic estimates of the stellar mass and radius. After correction of the bias (6% for the stellar radius and 3% for the mass), the performance of the calibrated relation is about 4% and 8% for estimating, respectively, the stellar radius and the stellar mass for masses less than 1.3 M ; the accuracy is twice as bad for higher mass stars and red giants.

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Section: The Asymptotic Expansion Used In Practicementioning

confidence: 89%

Asymptotic and measured large frequency separations

Mosser¹,

Michel²,

Belkacem³

et al. 2013

A&A

Self Cite

182

303

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“…Models with a large density contrast show a frequency difference between consecutive modes that is much smaller than for models at the bottom of the RGB or in the He-B phase. These properties have been measured by Bedding et al (2011) in the spectra of red giants observed by Kepler and also in those of CoRoT red giants (Mosser et al, 2011a). At a given ∆ ν (that of the red clump) the difference of period (∆ P) between consecutive modes gathers the stars in two groups: one characterized by targets with ∆ P > 100 s and one with ∆ P < 60 s. The comparison with theoretical computations allows us to identify these two groups with stars that are burning He at the center, for the first group, and with stars that are still burning H in a shell during the ascending RGB for the second one, and then to lift the degeneracy between RGB and He-B models with the same ∆ ν and ν max .…”

Section: Deviation From Asymptotic Approximation: Evolutionary Statementioning

confidence: 95%

“…On the other hand, the sample of red giants observed by CoRoT during the first two runs is dominated by red clump stars (Miglio et al, 2009;Mosser et al, 2010) and the analysis of their oscillation properties by Mosser et al (2011b) showed that all the modes are arranged in almost vertical lines corresponding to different radial orders, and that a large dispersion is found for dipole modes at ∆ ν ∼ 4 µHz, that is the value of the large separation corresponding to the red-clump luminosity. The comparison between these observational results and the theoretical predictions for the same stellar population (Montalbán et al, 2010b) is noteworthy.…”

Section: Deviation From Asymptotic Approximation: Evolutionary Statementioning

confidence: 99%

Adiabatic Solar-Like Oscillations in Red Giant Stars

Montalbán

Miglio

Noels

et al. 2011

Red Giants as Probes of the Structure and Evolution of the Milky Way

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Since the detection of non-radial solar-like oscillation modes in red giants with the CoRoT satellite, the interest in the asteroseismic properties of red giants and the link with their global properties and internal structure is substantially increasing. Moreover, more and more precise data are being collected with the space-based telescopes CoRoT and Kepler. In this paper we present a survey of the most relevant theoretical and observational results obtained up to now concerning the potential of solar-like oscillations in red giants. Structure and oscillation spectra of red giant modelsRed giants are cool stars with an extended and diluted convective envelope surrounding a dense core, which makes their structure and therefore their pulsation properties very different from those of the Sun. As in solar-like stars, however, their convective envelope can stochastically excite oscillation modes. The properties of oscillation modes depend on the behavior of the Brunt-Väisälä (N) and Lamb (S ℓ ) frequencies. In a first approximation we can describe the radial displacement due to the perturbation as:

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“…Bedding et al 2011;Mosser et al 2011b). The true period spacing ΔΠ 1 describes the constant period spacing of pure dipole g modes, which cannot be observed directly.…”

Section: Evolutionary Status Of Red Giant Heartbeat Starsmentioning

confidence: 99%

“…Previous analyses (Beck et al 2012;Deheuvels et al 2012;Mosser et al 2012a) only revealed the ratio of the (Mosser et al 2011b) for = 0, 1, 2 and 3 and are indicated with blue, red, green and yellow vertical bars, respectively. The effects of rotation are visible as the splitting of dipole modes, located in the centre of each panel.…”

Section: Testing Of the Rotational Profile From Forward Modellingmentioning

confidence: 99%

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

Beck

Hambleton

Vos

et al. 2014

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Context. The unparalleled photometric data obtained by NASA's Kepler Space Telescope has led to improved understanding of red giant stars and binary stars. Seismology allows us to constrain the properties of red giants. In addition to eclipsing binaries, eccentric non-eclipsing binaries that exhibit ellipsoidal modulations have been detected with Kepler. Aims. We aim to study the properties of eccentric binary systems containing a red giant star and to derive the parameters of the primary giant component. Methods. We applied asteroseismic techniques to determine the masses and radii of the primary component of each system. For a selected target, light and radial velocity curve modelling techniques were applied to extract the parameters of the system and its primary component. Stellar evolution and its effects on the evolution of the binary system were studied from theoretical models. Results. The paper presents the asteroseismic analysis of 18 pulsating red giants in eccentric binary systems, for which masses and radii were constrained. The orbital periods of these systems range from 20 to 440 days. The results of our ongoing radial velocity monitoring programme with the Hermes spectrograph reveal an eccentricity range of e = 0.2 to 0.76. As a case study we present a detailed analysis of KIC 5006817, whose rich oscillation spectrum allows for detailed seismic analysis. From seismology we constrain the rotational period of the envelope to be at least 165 d, which is roughly twice the orbital period. The stellar core rotates 13 times faster than the surface. From the spectrum and radial velocities we expect that the Doppler beaming signal should have a maximum amplitude of 300 ppm in the light curve. Fixing the mass and radius to the asteroseismically determined values, we find from our binary modelling a value of the gravity darkening exponent that is significantly larger than expected. Through binary modelling, we determine the mass of the secondary component to be 0.29 ± 0.03 M . Conclusions. For KIC 5006817 we exclude pseudo-synchronous rotation of the red giant with the orbit. The comparison of the results from seismology and modelling of the light curve shows a possible alignment of the rotational and orbital axis at the 2σ level. Red giant eccentric systems could be progenitors of cataclysmic variables and hot subdwarf B stars.

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The universal red-giant oscillation pattern

Cited by 171 publications

References 26 publications

Asymptotic and measured large frequency separations

Asymptotic and measured large frequency separations

Adiabatic Solar-Like Oscillations in Red Giant Stars

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

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