Asteroseismology of 19 low-luminosity red giant stars from<i>Kepler</i>

Hernández, F. Pérez; García, R. A.; Corsaro, E.; Triana, S. A.; Ridder, J. De

doi:10.1051/0004-6361/201628311

Cited by 32 publications

(44 citation statements)

References 45 publications

(68 reference statements)

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“…Though quick and simple to use, more robust estimations can be made when, for example, the average large frequency separations from model predicted radial mode frequencies and the use of gravity mode period spacings are considered in the parameter determinations (see Rodrigues et al 2017;Serenelli et al 2017). Though an improvement, these still do not exploit all of the information the individual modes contain, e.g., presence of acoustic glitches (Vorontsov 1988;Gough 1990;Miglio et al 2010;Pérez Hernández et al 2016;Verma et al 2017) and long term internal structure changes from curvature of the large frequency separation (Hekker & Christensen-Dalsgaard 2017;Mosser et al 2012).…”

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confidence: 99%

aims– a new tool for stellar parameter determinations using asteroseismic constraints

Rendle

Buldgen

Miglio

et al. 2019

Monthly Notices of the Royal Astronomical Society

101

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A key aspect in the determination of stellar properties is the comparison of observational constraints with predictions from stellar models. Asteroseismic Inference on a Massive Scale (AIMS) is an open source code that uses Bayesian statistics and a Markov Chain Monte Carlo approach to find a representative set of models that reproduce a given set of classical and asteroseismic constraints. These models are obtained by interpolation on a pre-calculated grid, thereby increasing computational efficiency. We test the accuracy of the different operational modes within AIMS for grids of stellar models computed with the Liège stellar evolution code (main sequence and red giants) and compare the results to those from another asteroseismic analysis pipeline, PARAM. Moreover, using artificial inputs generated from models within the grid (assuming the models to be correct), we focus on the impact on the precision of the code when considering different combinations of observational constraints (individual mode frequencies, period spacings, parallaxes, photospheric constraints,...). Our tests show the absolute limitations of precision on parameter inferences using synthetic data with AIMS, and the consistency of the code with expected parameter uncertainty distributions. Interpolation testing highlights the significance of the underlying physics to the analysis performance of AIMS and provides caution as to the upper limits in parameter step size. All tests demonstrate the flexibility and capability of AIMS as an analysis tool and its potential to perform accurate ensemble analysis with current and future asteroseismic data yields.

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confidence: 99%

aims– a new tool for stellar parameter determinations using asteroseismic constraints

Rendle

Buldgen

Miglio

et al. 2019

Monthly Notices of the Royal Astronomical Society

101

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“…Nevertheless, the dimensionless frequencies of the p-modes change so slowly that interpolations between models introduce errors much lower than the observational ones. This procedure was discussed in more detail in [54] and was found safe and consumes relatively less time.…”

Section: Fitting Proceduresmentioning

confidence: 99%

“…A χ 2 minimization, including p-mode frequencies and spectroscopic data, was applied to the grid of models. The general procedure is similar to that described in [54], but for these stars all the eigenfrequencies are approximately in the p-mode asymptotic regime and hence a simplified procedure can be done. Specifically we minimize the function…”

Section: Fitting Proceduresmentioning

confidence: 99%

“…In fact, introducing the dynamical time t dyn = (R 3 /GM ) 1/2 one has δω n0 /ω n0 = δt dyn /t dyn + δσ n0 /σ n0 where σ nl = ω nl /t dyn are the dimensionless frequencies. As in [54] we restore it in the minimization procedure adding a new χ 2 term, but increasing the error compared to the formal one derived from individual frequencies since this term can also include some influence from surface effects as discussed in [54]. Specifically we introduce the quantity…”

Section: Fitting Proceduresmentioning

confidence: 99%

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Influence of Magnetic Activity on the Determination of Stellar Parameters Through Asteroseismology

Hernández

García

Mathur

et al. 2019

Front. Astron. Space Sci.

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Magnetic activity changes the gravito-acoustic modes of solar-like stars and in particular their frequencies. There is an angular-degree dependence that is believed to be caused by the nonspherical nature of the magnetic activity in the stellar convective envelope. These changes in the mode frequencies could modify the small separation of low-degree modes (i.e. frequency difference between consecutive quadrupole and radial modes), which is sensitive to the core structure and hence to the evolutionary stage of the star. Determining global stellar parameters such as the age using mode frequencies at a given moment of the magnetic activity cycle could lead to biased results. Our estimations show that in general these errors are lower than other systematic uncertainties, but in some circumstances they can be as high as 10% in age and of a few percent in mass and radius. In addition, the frequency shifts caused by the magnetic activity are also frequency dependent. In the solar case this is a smooth function that will mostly be masked by the filtering of the so-called surface effects. However the observations of other stars suggest that there is an oscillatory component with a period close to the one corresponding to the acoustic depth of the He II zone. This could give rise to a misdetermination of some global stellar parameters, such as the helium abundance. Our computations show that the uncertainties introduced by this effect are lower than the 3% level. Pérez Hernández et al. Magnetic activity and asteroseismic determinations with several missions such as CoRoT [2], Kepler [3], K2 [4], and TESS [5] hundreds of main-sequence stars and dozens of thousands red giants have been observed.For many of these solar-like stars, the fundamental parameters have been estimated using the seismic measurements. Using the so-called "global asteroseismic scaling relations" [e.g. 6, 7, 8], masses and radii are obtained with a typical precision of 10% and 5% respectively [e.g. 9]. These estimates are model-independent because they rely on three observables: the effective temperature of the star, T eff , the frequency of the maximum power where the modes are located, ν max , and the large frequency spacing, ∆ν. The observed data from the Sun and other stars are used as references. Better results can be obtained using stellar models to derive mass, radius, and also age. In the case of grid-based modeling, when fitting spectroscopic observables and global seismic parameters all together to a pre-calculated grid of models, we can reach a precision better than 3% in radius, 6% in mass, and 23% in age [10]. The improvement is even better when incorporating the information from the individual mode frequencies with systematic uncertainties of 1% in radius, 3% in mass, and 15% in age [e.g. 11, 12, 13, 14, 15, 16].The precision reached by the asteroseismic inferences when the information of the individual modes is used, is among the best for field stars. Therefore, they are particularly interesting for other research fields such as galactic-a...

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“…In contrast to the case of solar‐like pulsating main‐sequence stars (e.g., see Lebreton & Goupil (); Silva Aguirre et al ()), the effectiveness of individual mode frequencies in determining stellar properties for giant stars has yet to be fully explored. However, when individual mode frequencies are available as additional constraints, expectations are that the precision and accuracy on the inferred radii and masses (hence age) of red giants are significantly improved (Huber et al (); Lillo‐Box et al (); Pérez Hernández et al ()). To illustrate the expected gain in precision when including radial‐mode frequencies, in Figure we show the posterior probability distribution functions for mass and age that we obtain by including different sets of constraints in the inference procedure.…”

Section: Expected Seismic Performancementioning

confidence: 99%

PLATO as it is: A legacy mission for Galactic archaeology

et al. 2017

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Deciphering the assembly history of the Milky Way is a formidable task, which becomes possible only if one can produce high‐resolution chrono‐chemo‐kinematical maps of the Galaxy. Data from large‐scale astrometric and spectroscopic surveys will soon provide us with a well‐defined view of the current chemo‐kinematical structure of the Milky Way, but it will only enable a blurred view on the temporal sequence that led to the present‐day Galaxy. As demonstrated by the (ongoing) exploitation of data from the pioneering photometric missions CoRoT, Kepler, and K2, asteroseismology provides the way forward: solar‐like oscillating giants are excellent evolutionary clocks thanks to the availability of seismic constraints on their mass and to the tight age–initial mass relation they adhere to. In this paper we identify five key outstanding questions relating to the formation and evolution of the Milky Way that will need precise and accurate ages for large samples of stars to be addressed, and we identify the requirements in terms of number of targets and the precision on the stellar properties that are needed to tackle such questions. By quantifying the asteroseismic yields expected from PLATO for red giant stars, we demonstrate that these requirements are within the capabilities of the current instrument design, provided that observations are sufficiently long to identify the evolutionary state and allow robust and precise determination of acoustic‐mode frequencies. This will allow us to harvest data of sufficient quality to reach a 10% precision in age. This is a fundamental prerequisite to then reach the more ambitious goal of a similar level of accuracy, which will be possible only if we have at hand a careful appraisal of systematic uncertainties on age deriving from our limited understanding of stellar physics, a goal that conveniently falls within the main aims of PLATO's core science. We therefore strongly endorse PLATO's current design and proposed observational strategy, and conclude that PLATO, as it is, will be a legacy mission for Galactic archaeology.

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Asteroseismology of 19 low-luminosity red giant stars fromKepler

Cited by 32 publications

References 45 publications

aims– a new tool for stellar parameter determinations using asteroseismic constraints

aims– a new tool for stellar parameter determinations using asteroseismic constraints

Influence of Magnetic Activity on the Determination of Stellar Parameters Through Asteroseismology

PLATO as it is: A legacy mission for Galactic archaeology

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