Asteroseismology of red giants: From analysing light curves to estimating ages

Davies, G. R.; Miglio, A.

doi:10.1002/asna.201612371

Cited by 52 publications

(62 citation statements)

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“…Estimating how the uncertainties on the measured seismic properties map onto the precision of the inferred stellar properties (primarily mass, hence age) is discussed in the next section. We notice that the uncertainties resulting from the simulations adopted here agree with the results from the approach presented in Davies & Miglio (()), where the seismic parameters determined from varying the length of the time series representing different space missions have been compared in a case study based on a specific star.…”

Section: Expected Seismic Performancesupporting

confidence: 81%

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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Section: Expected Seismic Performancesupporting

confidence: 81%

PLATO as it is: A legacy mission for Galactic archaeology

et al. 2017

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“…The finite length and cadence of the observations of a K2 field means there is a limit in our ability to extract properties from solar-like oscillations, and hence for how well ∆ν , and ν max can be obtained (e.g., Davies & Miglio 2016). This means that the asteroseismic calibration based on the K2 stars is limited to roughly the range of 2.1 < log g < 3.35 dex.…”

Section: Asteroseismically Calibrated Red Giant Catalogmentioning

confidence: 99%

The Radial Velocity Experiment (Rave): Fifth Data Release

Kunder

Kordopatis

Steinmetz

et al. 2017

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Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9 < I < 12) survey of stars randomly selected in the southern hemisphere. The RAVE medium-resolution spectra (R ∼ 7500) covering the Ca-triplet region (8410-8795Å) span the complete time frame from the start of RAVE observations in 2003 to their completion in 2013. Radial velocities from 520 781 spectra of 457 588 unique stars are presented, of which 255 922 stellar observations have parallaxes and proper motions from the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from highresolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalogue of red giant stars in the dereddened color (J − Ks) 0 interval (0.50,0.85) for which the gravities were calibrated based only on seismology. Further data products for sub-samples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the Vizier database.

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“…• Seismic pulsations of evolved red giant stars: While asteroseismic pulsations of main sequence stars are at a timescale of minutes (e.g., Chaplin et al 2011;Chaplin & Miglio 2013;Chaplin et al 2014), seismic pulsations of evolved red giant stars are at a time scale of days, following their larger radii and lower density, and they show sinusoidal modulations with amplitudes similar to that of orbital modulations (e.g., Hekker et al 2009;Davies & Miglio 2016;Sharma et al 2016). Therefore, such pulsations can be a source of a false positive scenario.…”

Section: Astrophysical Uses Of Optical Phase Curvesmentioning

confidence: 99%

The Astrophysics of Visible-light Orbital Phase Curves in the Space Age

Shporer

2017

PASP

129

107

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The field of visible-light continuous time series photometry is now at its golden age, manifested by the continuum of past (CoRoT, Kepler), present (K2), and future (TESS, PLATO) space-based surveys delivering high precision data with a long baseline for a large number of stars. The availability of the high quality data has enabled astrophysical studies not possible before, including for example detailed asteroseismic investigations and the study of the exoplanet census including small planets. This has also allowed to study the minute photometric variability following the orbital motion in stellar binaries and star-planet systems which is the subject of this review. We focus on systems with a main sequence primary and a low-mass secondary, from a small star to a massive planet. The orbital modulations are induced by a combination of gravitational and atmospheric processes, including the beaming effect, tidal ellipsoidal distortion, reflected light, and thermal emission. Therefore, the phase curve shape contains information about the companion's mass and atmospheric characteristics, making phase curves a useful astrophysical tool. For example, phase curves can be used to detect and measure the mass of short-period low-mass companions orbiting hot fast-rotating stars, out of reach of other detection methods. Another interesting application of phase curves is using the orbital phase modulations to look for non-transiting systems, which comprise the majority of stellar binary and star-planet systems. We discuss the science done with phase curves, the first results obtained so far, and the current difficulties and open questions related to this young and evolving subfield.

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Asteroseismology of red giants: From analysing light curves to estimating ages

Cited by 52 publications

References 50 publications

PLATO as it is: A legacy mission for Galactic archaeology

PLATO as it is: A legacy mission for Galactic archaeology

The Radial Velocity Experiment (Rave): Fifth Data Release

The Astrophysics of Visible-light Orbital Phase Curves in the Space Age

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