Characterizing solar-type stars from full-length <i>Kepler </i>data sets using the Asteroseismic Modeling Portal

Creevey, O.; Metcalfe, T. S.; Schultheis, M.; Salabert, D.; Bazot, M.; Thévenin, F.; Mathur, S.; Xu, Haiying; García, R. A.

doi:10.1051/0004-6361/201629496

Cited by 78 publications

(82 citation statements)

References 92 publications

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“…The asteroseismic rotation rates and ages for a ∼3 Gyr-old solar analog binary system (White et al, 2017) have been overplotted, validating asteroseismic rotation measurements and the age scale for sun-like Kepler stars. A few well-characterized solar analogs are shown with yellow points, including 18 Sco (Petit et al, 2008;Li et al, 2012;Mittag et al, 2016), α Cen A (Bazot et al, 2007;Bazot, Bourguignon, and ChristensenDalsgaard, 2012), and 16 Cyg A & B Creevey et al, 2017). Although some uncertainties remain for 18 Sco and α Cen A, these bright stars appear to follow the same pattern of anomalous rotation observed in the Kepler sample.…”

Section: Breakdown Of Magnetic Brakingmentioning

confidence: 78%

“…Note that the solar age and rotation rate (marked with a symbol) were used to calibrate the standard model beyond the 0.5-2.5 Gyr age range of clusters. Asteroseismic ages for the Kepler sample (black points and 16 Cyg) have been updated with values from Creevey et al (2017). The shaded region represents the expected dispersion due to the range of masses and metallicities within the sample (e.g., the two high points are lower metallicity stars, giving them thinner convection zones that reach the critical Rossby number at faster rotation rates).…”

Section: Breakdown Of Magnetic Brakingmentioning

confidence: 99%

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Magnetic Evolution and the Disappearance of Sun-Like Activity Cycles

Metcalfe

Saders

2017

Sol Phys

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After decades of effort, the solar activity cycle is exceptionally well characterized but it remains poorly understood. Pioneering work at the Mount Wilson Observatory demonstrated that other sun-like stars also show regular activity cycles, and suggested two possible relationships between the rotation rate and the length of the cycle. Neither of these relationships correctly describe the properties of the Sun, a peculiarity that demands explanation. Recent discoveries have started to shed light on this issue, suggesting that the Sun's rotation rate and magnetic field are currently in a transitional phase that occurs in all middleaged stars. Motivated by these developments, we identify the manifestation of this magnetic transition in the best available data on stellar cycles. We propose a reinterpretation of previously published observations to suggest that the solar cycle may be growing longer on stellar evolutionary timescales, and that the cycle might disappear sometime in the next 0.8-2.4 Gyr. Future tests of this hypothesis will come from ground-based activity monitoring of Kepler targets that span the magnetic transition, and from asteroseismology with the TESS mission to determine precise masses and ages for bright stars with known cycles.

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Section: Breakdown Of Magnetic Brakingmentioning

confidence: 78%

Section: Breakdown Of Magnetic Brakingmentioning

confidence: 99%

Magnetic Evolution and the Disappearance of Sun-Like Activity Cycles

Metcalfe

Saders

2017

Sol Phys

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“…A change in the mixing length of the atmosphere model of the magnitude discussed here will therefore not impact our results. We note that detailed seismic modeling of dwarfs and subgiants suggests a range of mixing lengths that depend on temperature, composition, and gravity (see e.g., Bonaca et al 2012;Metcalfe et al 2014;Creevey et al 2017;Silva Aguirre et al 2017). However, none of these studies have more than a single star in the more evolved gravity ranges we are considering.…”

Section: A Metallicity-dependent Mixing Lengthmentioning

confidence: 95%

The Correlation between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era

Tayar

Somers

Pinsonneault

et al. 2017

ApJ

110

105

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In the updated APOGEE-Kepler catalog, we have asteroseismic and spectroscopic data for over 3000 first ascent red giants. Given the size and accuracy of this sample, these data offer an unprecedented test of the accuracy of stellar models on the post-main-sequence. When we compare these data to theoretical predictions, we find a metallicity dependent temperature offset with a slope of around 100 K per dex in metallicity. We find that this effect is present in all model grids tested, and that theoretical uncertainties in the models, correlated spectroscopic errors, and shifts in the asteroseismic mass scale are insufficient to explain this effect. Stellar models can be brought into agreement with the data if a metallicity-dependent convective mixing length is used, with Δα ML, YREC ∼0.2 per dex in metallicity, a trend inconsistent with the predictions of three-dimensional stellar convection simulations. If this effect is not taken into account, isochrone ages for red giants from the Gaia data will be off by as much as a factor of two even at modest deviations from solar metallicity ([Fe/H]=−0.5).

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“…We have used the latest version of the Asteroseismic Modeling Portal (AMP, [27]) to obtain reliable stellar properties from the complete Kepler data sets ( [28]). For each star in the sample, we repeated the modeling with and without a luminosity constraint derived from Gaia DR1 parallaxes ( [2]), allowing us to isolate the impact of this constraint on the inferred stellar properties.…”

Section: Asteroseismology With Keplermentioning

confidence: 99%

The impact of Gaia DR1 on asteroseismic inferences from Kepler

Metcalfe

Creevey

Saders³

2017

EPJ Web Conf.

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Abstract. The Kepler mission has been fantastic for asteroseismology of solar-type stars, but the targets are typically quite distant. As a consequence, the reliability of asteroseismic modeling has been limited by the precision of additional constraints from highresolution spectroscopy and parallax measurements. A precise luminosity is particularly useful to minimize potential biases due to the intrinsic correlation between stellar mass and initial helium abundance. We have applied the latest version of the Asteroseismic Modeling Portal (AMP) to the complete Kepler data sets for 30 stars with known rotation rates and chromospheric activity levels. We compare the stellar properties derived with and without the measured parallaxes from the first data release of Gaia. We find that in most cases the masses and ages inferred from asteroseismology shift within their uncertainties. For a few targets that show larger shifts, the updated stellar properties only strengthen previous conclusions about anomalous rotation in middle-aged stars. MotivationThe correlation between stellar mass and initial helium abundance is a long-standing problem in modeling solar-type stars. Increasing either the mass or the initial helium yields a model with a higher luminosity, so we can trade off one parameter for the other while still satisfying the observational constraints ([1]). Asteroseismic observations can reduce the severity of this problem by providing a strong constraint on the stellar radius, but the issue cannot be avoided entirely without a more direct constraint on the stellar luminosity. Without such a constraint, the correlation can lead to systematic biases in the stellar properties inferred from asteroseismology. In this paper, we examine the impact of including luminosity constraints derived from Gaia DR1 parallaxes ([2]) for a sample of 30 Kepler targets with known rotation rates ([3]) and chromospheric activity levels ([4]). Our goal is to evaluate the possibility of systematic biases in the asteroseismic masses and ages for stars with anomalous rotation compared to empirical gyrochronology relations ([5]), with implications for a new theory of magnetic evolution beyond middle age ([6]).Until recently, it was presumed that rotation and magnetism decay together throughout the lives of solar-type stars ([7, 8]). Although stars are formed with a range of initial rotation rates, the stellar winds entrained in their magnetic fields lead to angular momentum loss from magnetic braking. This forces convergence to a single rotation rate at a given mass after roughly 500 Myr. The Kepler mission allowed the measurement of rotation periods in old field stars whose masses and ages could be determined from asteroseismology. These new data revealed a population of field stars rotating

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Characterizing solar-type stars from full-length Kepler data sets using the Asteroseismic Modeling Portal

Cited by 78 publications

References 92 publications

Magnetic Evolution and the Disappearance of Sun-Like Activity Cycles

Magnetic Evolution and the Disappearance of Sun-Like Activity Cycles

The Correlation between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era

The impact of Gaia DR1 on asteroseismic inferences from Kepler

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