A Precise Asteroseismic Age and Radius for the Evolved Sun-Like Star Kic 11026764

Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doğan, G.; Eggenberger, P.; Bedding, Timothy R.; Bruntt, H.; Creevey, O.; Quirion, Pierre-Olivier; Stello, D.; Bonanno, A.; Aguirre, V. Silva; Basu, Sarbani; Esch, Lisa; Gai, Ning; Mauro, M. P. Di; Kosovichev, A. G.; Kitiashvili, Irina; Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.; Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff, C.; Frandsen, S.; Wilson, Paul; Brown, Timothy M.; Christensen‐Dalsgaard, J.; Gilliland, Ronald L.; Kjeldsen, H.; Campante, Tiago L.; Fletcher, S.M.; Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.; Ballot, J.; Broomhall, Anne-Marie; Elsworth, Y.; Hekker, S.; Huber, Daniel; Mathur, S.; New, R.; Roxburgh, I. W.; Sato, Kumiko; White, T. R.; Borucki, W. J.; Koch, David; Jenkins, Jon M.

doi:10.1088/0004-637x/723/2/1583

Cited by 142 publications

(121 citation statements)

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“…This demonstrates that seismic observations of subgiants have the potential to contribute to ongoing debates, such as the question of the amount of core overshooting, the efficiency of convection, and the abundances of heavy elements in stars. This is all the more exciting because the space mission Kepler has claimed the detection of = 1 avoided crossings in several targets (Chaplin et al 2010;Metcalfe et al 2010).…”

Section: Resultsmentioning

confidence: 99%

Constraints on the structure of the core of subgiants via mixed modes: the case of HD 49385

Deheuvels

Michel

2011

A&A

115

165

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Context. The solar-like pulsator HD 49385 was observed with the CoRoT satellite over a period of 137 days. The analysis of its oscillation spectrum yielded precise estimates of the mode frequencies over nine radial orders and distinguished some unusual characteristics, such as some modes outside the identified ridges in the échelle diagram and that the curvature of the = 1 ridge differs significantly from that of the = 0 ridge. Aims. We search for stellar models that can reproduce the peculiar features of the oscillation spectrum of HD 49385. After showing that they can be accounted for only by a low-frequency = 1 avoided crossing, we investigate the information provided by the mixed modes about the structure of the core of HD 49385. Methods. We propose a toy-model to study the case of avoided crossings with a strong coupling between the p-mode and g-mode cavities in order to establish the presence of mixed modes in the spectrum of HD 49385. We then show that traditional optimization techniques are ill-suited to stars with mixed modes in avoided crossing. We propose a new approach to the computation of grids of models that we apply to HD 49385. Results. The detection of mixed modes leads us to establish the post-main-sequence status of HD 49385. The mixed mode frequencies suggest that there is a strong coupling between the p-mode and g-mode cavities. As a result, we show that the amount of core overshooting in HD 49385 is either very small (0 < α ov < 0.05) or moderate (0.18 < α ov < 0.20). The mixing length parameter is found to be significantly lower than the solar one (α CGM = 0.55 ± 0.04 compared to the solar value α = 0.64). Finally, we show that the revised solar abundances of Asplund ensure closer agreement with the observations than the classical ones of Grevesse & Noels. At each step, we investigate the origin and meaning of these seismic diagnostics in terms of the physical structure of the star. Conclusions. The subgiant HD 49385 is the first star for which a thorough modeling has been attempted to reproduce all the properties of an avoided crossing. It has provided the opportunity to show that the study of the coupling between the cavities in these stars can provide valuable insight into open questions such as core overshooting, the efficiency of convection, and the abundances of heavy elements in stars.

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Section: Resultsmentioning

confidence: 99%

Constraints on the structure of the core of subgiants via mixed modes: the case of HD 49385

Deheuvels

Michel

2011

A&A

115

165

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“…To obtain an asteroseismic estimate of the stellar mass and radius we employed the code Catania-GARSTEC (Bonanno et al 2002b), following the approach and the physical input described in Metcalfe et al (2010) for KIC 11026764. In our grid model search we considered the average values from ROTFIT and Bruntt et al (2012) as astrophysical constraints, and the large separation Δν = 49.6 μHz (Appourchaux et al 2012) as the main asteroseismic constraint.…”

Section: Observations Of Kic 5955122mentioning

confidence: 99%

Magnetic activity, differential rotation, and dynamo action in the pulsating F9IV star KIC 5955122

Bonanno

Fröhlich

Karoff

et al. 2014

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We present photometric spot modeling of the nearly four-year long light-curve of the Kepler target KIC 5955122 in terms of persisting dark circular surface features. With a Bayesian technique, we produced a plausible surface map that shows dozens of small spots. After some artifacts are removed, the residuals are at ±0.16 mmag. The shortest rotational period found is P = 16.4 ± 0.2 days. The equator-to-pole extrapolated differential rotation is 0.25 ± 0.02 rad/d. The spots are roughly half as bright as the unperturbed stellar photosphere. Spot latitudes are restricted to the zone ±60 • latitude. There is no indication for any near-pole spots. In addition, the p-mode pulsations enabled us to determine the evolutionary status of the star, the extension of the convective zone, and its radius and mass. We discuss the possibility that the clear signature of active regions in the light curve of the F9IV star KIC 5955122 is produced by a flux-transport dynamo action at the base of the convection zone. In particular, we argue that this star has evolved from an active to a quiet status during the Q0-Q16 period of observation, and we predict, according to our dynamo model, that the characteristic activity cycle is of the order of the solar one.

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“…Stello et al 2013Stello et al , 2015Chaplin et al 2015). These data allow us to determine accurate stellar properties that help to constrain stellar evolution models (Metcalfe et al 2010;Mathur et al 2012) and improve the determination of the properties of the exoplanets they might host (Guillot & Havel 2011;Huber et al 2013). A review of the progress with Kepler in the field of the red giant stars can be found in Christensen-Dalsgaard (2012) and García & Stello (2015).…”

Section: Introductionmentioning

confidence: 99%

Asteroseismology of 19 low-luminosity red giant stars fromKepler

Hernández

García

Corsaro

et al. 2016

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Context. Frequencies of acoustic and mixed modes in red giant stars are now determined with high precision thanks to the long continuous observations provided by the NASA's Kepler mission. Here we consider the eigenfrequencies of nineteen low-luminosity red giant stars selected in a recent publication for a detailed peak-bagging analysis. Aims. Our objective is to obtain stellar parameters by using individual mode frequencies and spectroscopic information. Methods. We use a forward modelling technique based on a minimization procedure combining the frequencies of the p-modes, the period spacing of the dipolar modes, and the spectroscopic data. Results. Consistent results between the forward modelling technique and values derived from the seismic scaling relations are found but the errors derived using the former technique are lower. The average error for log g is 0.002 dex, compared to 0.011 dex from the frequency of maximum power, ν max , and 0.10 dex from the spectroscopic analysis. Relative errors in the masses and radii are on average 2% and 0.5% respectively, compared to 3% and 2% derived from the scaling relations. No reliable determination of the initial helium abundances and the mixing length parameters could be made. Finally, for our grid of models with given input physics, we found that low-mass stars require higher values of the overshooting parameter.

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A Precise Asteroseismic Age and Radius for the Evolved Sun-Like Star Kic 11026764

Cited by 142 publications

References 100 publications

Constraints on the structure of the core of subgiants via mixed modes: the case of HD 49385

Constraints on the structure of the core of subgiants via mixed modes: the case of HD 49385

Magnetic activity, differential rotation, and dynamo action in the pulsating F9IV star KIC 5955122

Asteroseismology of 19 low-luminosity red giant stars fromKepler

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