A Bayesian approach to scaling relations for amplitudes of solar-like oscillations in Kepler stars

Corsaro, E.; Fröhlich, H.‐E.; Bonanno, A.; Huber, Daniel; Bedding, Timothy R.; Benomar, O.; Ridder, J. De; Stello, Dennis

doi:10.1093/mnras/stt059

Cited by 82 publications

(120 citation statements)

References 61 publications

(98 reference statements)

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“…In solar-type oscillating stars, the outer convective layer is believed to drive modes with a resonant frequency v CV /H p , where v CV is the convection velocity, and a mode energy that is roughly equal to the kinetic energy of a single convection eddy. The underlying physics is still not properly understood but a number of scaling relations aiming to predict mode amplitudes by scaling from the Sun's values have been derived and discussed (see, e.g., Corsaro et al 2013, and references therein). Testing such scaling relations with observational data is vital for a better understanding of stellar oscillations but not only their physical interpretation is still a matter of debate, also the actual measurements are far from being straightforward to perform.…”

Section: Pulsation Amplitudesmentioning

confidence: 99%

“…From theoretical considerations it is assumed that the bolometric mode amplitude scales as (L/M) p (T eff ) −t , where it is not yet fully clear whether or not it scales with L and M to the same power and what are the specific values of the exponents (e.g., Stello et al 2011;Huber et al 2011;Corsaro et al 2013). For the vast majority of the rather faint stars observed with Kepler, however, the luminosity is simply unknown (or poorly determined via the seismic radius and effective temperature) and it is therefore difficult to test such a scaling relation.…”

Section: Pulsation Amplitudesmentioning

confidence: 99%

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The connection between stellar granulation and oscillation as seen by theKeplermission

Kallinger

Ridder

Hekker

et al. 2014

A&A

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Context. The long and almost continuous observations by Kepler show clear evidence of a granulation background signal in a large sample of stars, which is interpreted as the surface manifestation of convection. It has been shown that its characteristic timescale and rms intensity fluctuation scale with the peak frequency (ν max ) of the solar-like oscillations. Various attempts have been made to quantify the observed signal, to determine scaling relations for its characteristic parameters, and to compare them to theoretical predictions. Even though they are consistent on a global scale, large systematic differences of an unknown origin remain between different methods, as well as between the observations and simulations. Aims. We aim to study different approaches to quantifying the signature of stellar granulation and to search for a unified model that reproduces the observed signal best in a wide variety of stars. We then aim to define empirical scaling relations between the granulation properties and ν max and various other stellar parameters. Methods. We use a probabilistic method to compare different approaches to extracting the granulation signal. We fit the power density spectra of a large set of Kepler targets, determine the granulation and global oscillation parameter, and quantify scaling relations between them. Results. We establish that a depression in power at about ν max /2, known from the Sun and a few other main-sequence stars, is also statistically significant in red giants and that a super-Lorentzian function with two components is best suited to reproducing the granulation signal in the broader vicinity of the pulsation power excess. We also establish that the specific choice of the background model can affect the determination of ν max , introducing systematic uncertainties that can significantly exceed the random uncertainties. We find the characteristic frequency (i.e., inverse timescale) and amplitude of both background components to tightly scale with ν max for a wide variety of stars (about 2-2000 μHz in ν max ), and quantify a mass dependency of the latter. To enable comparison with theoretical predictions (which do not include the observed power depression), we computed effective timescales and bolometric intensity fluctuations and found them to approximately scale as τ eff ∝ g −0.85 T −0.4 and A gran ∝ (g 2 M) −1/4 (or more conveniently R/M 3/4 ), respectively. Similarly, the bolometric pulsation amplitude scales approximately as A puls ∝ (g 2 M) −1/3 (or R 4/3 /M), which implicitly verifies a separate mass and luminosity dependence of A puls . We have also checked our scaling relations with solar reference values and find them in good agreement. Conclusions. We provide a thorough analysis of the granulation background signal in a large sample of stars, from which we establish a unified model that allows us to accurately extract the granulation and global oscillation parameter. The resulting scaling relations allow a simple estimate of the overall spectral shape of any solar-ty...

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Section: Pulsation Amplitudesmentioning

confidence: 99%

Section: Pulsation Amplitudesmentioning

confidence: 99%

The connection between stellar granulation and oscillation as seen by theKeplermission

Kallinger

Ridder

Hekker

et al. 2014

A&A

Self Cite

225

352

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“…These relations have been applied in numerous papers since then (e.g. Kallinger et al 2010b;Huber et al 2011;Corsaro et al 2013). Results from scaling relations have recently been compared with results of independent methods.…”

Section: Fig 1 Five Examples Ofmentioning

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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“…There has been considerable effort towards understanding how the amplitudes of solar-like oscillations vary from the Sun to other stars, both theoretically [52][53][54][55][56][57][58][59][60] and observationally [61][62][63][64][65][66][67][68]. A good measurement of the solar amplitude with Kepler would serve as an important calibration.…”

Section: First Indirect Detection Of Solar Oscillations In Intensity mentioning

confidence: 99%

Seismology of Giant Planets: General Overview and Results from theKeplerK2 Observations of Neptune

Gaulme

2017

EPJ Web Conf.

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Abstract. For this invited contribution, I was asked to give an overview about the application of helio and asteroseismic techniques to study the interior of giant planets, and to specifically present the recent observations of Neptune by Kepler K2. Seismology applied to giant planets could drastically change our understanding of their deep interiors, as it has happened with the Earth, the Sun, and many main-sequence and evolved stars. The study of giant planets' composition is important for understanding both the mechanisms enabling their formation and the origins of planetary systems, in particular our own. Unfortunately, its determination is complicated by the fact that their interior is thought not to be homogeneous, so that spectroscopic determinations of atmospheric abundances are probably not representative of the planet as a whole. Instead, the determination of their composition and structure must rely on indirect measurements and interior models. Giant planets are mostly fluid and convective, which makes their seismology much closer to that of solar-like stars than that of terrestrial planets. Hence, helioseismology techniques naturally transfer to giant planets. In addition, two alternative methods can be used: photometry of the solar light reflected by planetary atmospheres, and ring seismology in the specific case of Saturn. The current decade has been promising thanks to the detection of Jupiter's acoustic oscillations with the ground-based imaging-spectrometer SYMPA and indirect detection of Saturn's f -modes in its rings by the NASA Cassini orbiter. This has motivated new projects of ground-based and space-borne instruments that are under development. The K2 observations represented the first opportunity to search for planetary oscillations with visible photometry. Despite the excellent quality of K2 data, the noise level of the power spectrum of the light curve was not low enough to detect Neptune's oscillations. The main results from the K2 observations are the clear detection of the well-known differential rotation of Neptune, measured for the first time through the rotational modulation of its photometry, and the detection of the Sun's oscillations, for the first time in an indirect way in intensity measurements.

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A Bayesian approach to scaling relations for amplitudes of solar-like oscillations in Kepler stars

Cited by 82 publications

References 61 publications

The connection between stellar granulation and oscillation as seen by theKeplermission

The connection between stellar granulation and oscillation as seen by theKeplermission

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

Seismology of Giant Planets: General Overview and Results from theKeplerK2 Observations of Neptune

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