Asteroseismology of solar‐type stars with Kepler I: Data analysis

Karoff, C.; Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García, Rafael A.; Houdek, G.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Christensen‐Dalsgaard, J.; Kjeldsen, H.; Basu, Sarbani; Bedding, Timothy R.; Campante, Tiago L.; Eggenberger, P.; Fletcher, S.M.; Gaulme, P.; Handberg, R.; Hekker, S.; Martić, M.; Mathur, S.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Stello, Dennis; Verner, G. A.; Belkacem, K.; Biazzo, K.; Cunha, M. S.; Gruberbauer, M.; Guzik, J. A.; Kupka, F.; Leroy, B.; Ludwig, H.‐G.; Mathis, S.; Noels, A.; Noyes, R. W.; Cortés, T. Roca; Roth, M.; Sato, Kumiko; Schmitt, J. H. M. M.; Suran, M. D.; Trampedach, Regner; Uytterhoeven, K.; Ventura, R.; Wilson, Paul

doi:10.1002/asna.201011438

Cited by 13 publications

(12 citation statements)

References 22 publications

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“…Although fitting a background is a relatively low-dimensional problem, there is no universal model that can be used for all the stars as it closely depends on how many physical phenomena are involved, namely granulation (Harvey 1985;Aigrain et al 2004;Michel et al 2009), and the more recently investigated bright spots activity (faculae) Karoff et al 2010;Karoff 2012;Karoff et al 2013a). As a consequence (since the asteroseismic analysis of the oscillations is sensitive to the stellar background components) assuming different models may sensibly change the final results (see the discussion by A14 concerning the impact of the background on the oscillation characteristic parameters).…”

Section: Background Modelingmentioning

confidence: 99%

DIAMONDS: A new Bayesian nested sampling tool

Corsaro

Ridder

2014

A&A

120

142

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Context. Thanks to the advent of the space-based missions CoRoT and NASA's Kepler, the asteroseismology of solar-like oscillations is now at the base of our understanding about stellar physics. The Kepler spacecraft, especially, is releasing excellent photometric observations of more than three years length in high duty cycle, which contain a large amount of information that has not yet been investigated. Aims. To exploit the full potential of Kepler light curves, sophisticated and robust analysis tools are now required more than ever. Characterizing single stars with an unprecedented level of accuracy and subsequently analyzing stellar populations in detail are fundamental to further constrain stellar structure and evolutionary models. Methods. We developed a new code, termed D, for Bayesian parameter estimation and model comparison by means of the nested sampling Monte Carlo (NSMC) algorithm, an efficient and powerful method very suitable for high-dimensional and multimodal problems. A detailed description of the features implemented in the code is given with a focus on the novelties and differences with respect to other existing methods based on NSMC. D is then tested on the bright F8 V star KIC 9139163, a challenging target for peak-bagging analysis due to its large number of oscillation peaks observed, which are coupled to the blending that occurs between = 2, 0 peaks, and the strong stellar background signal. We further strain the performance of the approach by adopting a 1147.5 days-long Kepler light curve, accounting for more than 840 000 data bins in the power spectrum of the star. Results. The D code is able to provide robust results for the peak-bagging analysis of KIC 9139163, while preserving a considerable computational efficiency for identifying the solution at the same time. We test the detection of different astrophysical backgrounds in the star and provide a criterion based on the Bayesian evidence for assessing the peak significance of the detected oscillations in detail. We present results for 59 individual oscillation frequencies, amplitudes and linewidths and provide a detailed comparison to the existing values in the literature, from which significant deviations are found when a different background is used. Lastly, we successfully demonstrate an innovative approach to peak bagging that exploits the capability of D to sample multi-modal distributions, which is of great potential for possible future automatization of the analysis technique.

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Section: Background Modelingmentioning

confidence: 99%

DIAMONDS: A new Bayesian nested sampling tool

Corsaro

Ridder

2014

A&A

120

142

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“…the c parameter in Kjeldsen et al (2008b)], the amount of smoothing applied to the power spectrum (a wider smoothing window can reduce the amplitude of the p-mode power excess) and also an appropriate contribution to model the stellar background (e.g. Harvey 1985;Karoff et al 2010b). As each method addressed these problems in a slightly different way, the amplitudes they obtained were scaled differently from each other.…”

Section: A Maxmentioning

confidence: 99%

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

Verner

Elsworth

Chaplin

et al. 2011

Monthly Notices of the Royal Astronomical Society

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110

109

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We present the asteroseismic analysis of 1948 F‐, G‐ and K‐type main‐sequence and subgiant stars observed by the National Aeronautics and Space Administration Kepler mission. We detect and characterize solar‐like oscillations in 642 of these stars. This represents the largest cohort of main‐sequence and subgiant solar‐like oscillators observed to date. The photometric observations are analysed using the methods developed by nine independent research teams. The results are combined to validate the determined global asteroseismic parameters and calculate the relative precision by which the parameters can be obtained. We correlate the relative number of detected solar‐like oscillators with stellar parameters from the Kepler Input Catalogue and find a deficiency for stars with effective temperatures in the range 5300 ≲Teff≲ 5700 K and a drop‐off in detected oscillations in stars approaching the red edge of the classical instability strip. We compare the power‐law relationships between the frequency of peak power, νmax, the mean large frequency separation, Δν, and the maximum mode amplitude, Amax, and show that there are significant method‐dependent differences in the results obtained. This illustrates the need for multiple complementary analysis methods to be used to assess the robustness and reproducibility of results derived from global asteroseismic parameters.

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“…where ν is the frequency, and σ c , τ c , and α c are 3 free parameters; τ c represents the characteristic time of the granulation. Some authors (see Karoff et al 2010) add also another contribution due to faculae. Faculae are brights points visible at the solar surface that should also exist on other solar-type stars.…”

Section: Power Spectrum Of Convection and Backgroundmentioning

confidence: 99%

Current methods for analyzing light curves of solar‐like stars

Ballot

2010

Astron Nachr

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CoRoT has allowed a quantitative leap for the solar-like-star seismology thanks to 5-month-long uninterrupted timeseries of high-precision photometric data. Kepler is also starting to deliver similar data. Now, several F and G main-sequence stars have been analyzed. The techniques developed to interpret light curves directly inherit from the experience got on the Sun with helioseismology. I describe in this review the methods currently used to analyze these light curves. First, these data provide an accurate determination of the stellar rotation rate. This is possible thanks to the magnetic activity of stars. The power spectra of light curves put also constraints on the stellar granulation, which can be directly compared to 3-D stellar atmosphere models; this shows still unexplained discrepancies. I then detailed a standard method for extracting p-mode characteristics (frequency, amplitude and lifetime). CoRoT has revealed unexpected short life times for F stars. Last, I also discuss errors and biases of mode frequencies, especially the ones due to the simplified description of the rotation generally used.Comment: 7 pages, 4 figures, invited review for the proceedings of the HELAS-IV International Conference, accepted for publication in Astronomische Nachrichte

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Asteroseismology of solar‐type stars with Kepler I: Data analysis

Cited by 13 publications

References 22 publications

DIAMONDS: A new Bayesian nested sampling tool

DIAMONDS: A new Bayesian nested sampling tool

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

Current methods for analyzing light curves of solar‐like stars

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