Global asteroseismic properties of solar-like oscillations observed by Kepler: a comparison of complementary analysis methods

Verner, G. A.; Elsworth, Y.; Chaplin, W. J.; Campante, Tiago L.; Corsaro, E.; Gaulme, P.; Hekker, S.; Huber, Daniel; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Ballot, J.; Bedding, Timothy R.; Bonanno, A.; Broomhall, Anne-Marie; García, R. A.; Handberg, R.; New, R.; Stello, Dennis; Régulo, C.; Roxburgh, I. W.; Salabert, D.; White, T. R.; Caldwell, Douglas A.; Christiansen, Jessie L.; Fanelli, M. N.

doi:10.1111/j.1365-2966.2011.18968.x

Cited by 111 publications

(116 citation statements)

References 59 publications

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“…We measured 74.9 ± 0.4 μHz. Other methods, similar to those used by Verner et al (2011), converge on the same value. Comparison of different methods has shown that the EACF provides reliable results.…”

Section: Mean Seismic Global Parametersmentioning

confidence: 90%

“…This means that there are a large number of main-sequence stars and subgiants that can serve as seismic references. We consider that an EACF of 100 is enough for the reference, so that we currently identify more than 80 possible references for subgiants and main-sequence stars, according to previous CoRoT and Kepler observations (e.g., Verner et al 2011). The only domain where the set of reference stars appears to be loose in the main sequence for stars with a lower mass than the Sun is for ν max ≥ 3.6 mHz.…”

Section: Choosing a Referencementioning

confidence: 99%

“…A strong smoothing of the spectrum with an apodized 300-μHz window was applied to show the evidence of excess power around 1.6 mHz ( Fig. 3), as determined with several methods (Verner et al 2011). In the expected range, this signature cannot be confused with the low-frequency contribution described by Eq.…”

Section: Excess Power At High Frequencymentioning

confidence: 99%

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Differential asteroseismic study of seismic twins observed by CoRoT

Ozel

Mosser

Dupret

et al. 2013

A&A

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Context. The CoRoT short asteroseismic runs give us the opportunity to observe a large variety of late-type stars through their solarlike oscillations. We report the observation and modeling of the F5V star HD 175272. Aims. Our aim is to define a method for extracting as much information as possible from a noisy oscillation spectrum. Methods. We followed a differential approach that consists of using a well-known star as a reference to characterize another star. We used classical tools such as the envelope autocorrelation function to derive the global seismic parameters of the star. We compared HD 175272 with HD 181420 through a linear approach, because they appear to be asteroseismic twins. Results. The comparison with the reference star enables us to substantially enhance the scientific output for HD 175272. First, we determined its global characteristics through a detailed seismic analysis of HD 181420. Second, with our differential approach, we measured the difference of mass, radius and age between HD 175272 and HD 181420. Conclusions. We have developed a general method able to derive asteroseismic constraints on a star even in case of low-quality data. This method can be applied to stars with interesting properties but low signal-to-noise ratio oscillation spectrum, such as stars hosting an exoplanet or members of a binary system.

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Section: Mean Seismic Global Parametersmentioning

confidence: 90%

Section: Choosing a Referencementioning

confidence: 99%

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Differential asteroseismic study of seismic twins observed by CoRoT

Ozel

Mosser

Dupret

et al. 2013

A&A

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“…It relies on a global description of the oscillation spectrum, which considers that the mean values of the seismic parameters are determined in a large frequency range around ν max ). Such a description has shown interesting properties when compared to a local one that provides the large separation from a limited frequency range only around ν max (Verner et al 2011;Hekker et al 2012). It is straightforward to make the link between both asymptotic and observed descriptions of the radial oscillation pattern with a second-order development in (n − n max )/n max of the asymptotic expression.…”

Section: Taking Into Account the Curvaturementioning

confidence: 99%

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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“…This mass interval exhibits a large range of the physical properties of convective envelopes (such as the depth, physical size, mass, and density), as well as in the overall stellar luminosity transported by convection. These types of stars are also targets for asteroseismic studies (e.g., Verner et al 2011), which have the potential to give precise measurements of stellar properties for large numbers of stars. The goal here is to determine how the convection, differential rotation, and meridional circulation is influenced by stellar mass, and to see if general trends or scaling laws can be extracted that will guide a deeper understanding of the inner hydrodynamics of these stars.…”

Section: Introductionmentioning

confidence: 99%

Convection and differential rotation properties of G and K stars computed with the ASH code

Matt

Cao

Brown³

et al. 2011

Astron Nachr

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The stellar luminosity and depth of the convective envelope vary rapidly with mass for G-and K-type main sequence stars. In order to understand how these properties influence the convective turbulence, differential rotation, and meridional circulation, we have carried out 3D dynamical simulations of the interiors of rotating main sequence stars, using the anelastic spherical harmonic (ASH) code. The stars in our simulations have masses of 0.5, 0.7, 0.9, and 1.1 M , corresponding to spectral types K7 through G0, and rotate at the same angular speed as the Sun. We identify several trends of convection zone properties with stellar mass, exhibited by the simulations. The convective velocities, temperature contrast between up-and downflows, and meridional circulation velocities all increase with stellar luminosity. As a consequence of the trend in convective velocity, the Rossby number (at a fixed rotation rate) increases and the convective turnover timescales decrease significantly with increasing stellar mass. The three lowest mass cases exhibit solar-like differential rotation, in a sense that they show a maximum rotation at the equator and minimum at higher latitudes, but the 1.1 M case exhibits anti-solar rotation. At low mass, the meridional circulation is multi-cellular and aligned with the rotation axis; as the mass increases, the circulation pattern tends toward a unicellular structure covering each hemisphere in the convection zone.

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Global asteroseismic properties of solar-like oscillations observed by Kepler: a comparison of complementary analysis methods

Cited by 111 publications

References 59 publications

Differential asteroseismic study of seismic twins observed by CoRoT

Differential asteroseismic study of seismic twins observed by CoRoT

Asymptotic and measured large frequency separations

Convection and differential rotation properties of G and K stars computed with the ASH code

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