arXiv subjects

F. Baudin

Publications and source records attributed to F. Baudin.

At least 19 recordsLinked to original sources

arXiv2021

Modeling of two CoRoT solar analogues constrained by seismic and spectroscopic analysis

Solar analogues are important stars to study for understanding the properties of the Sun. Evolutionary modeling, combined with seismic and spectroscopic analysis, becomes a powerful method to characterize stellar intrinsic parameters, such as mass, radius, metallicity and age.However, these characteristics, relevant for other aspects of astrophysics or exoplanetary system physics for example, are difficult to obtain with a high precision and/or accuracy. The goal of this study is to characterize the two solar analogues HD42618 and HD43587, observed by CoRoT. In particular, we aim to infer precise mass, radius, and age, using evolutionary modeling constrained by spectroscopic, photometric, and seismic analysis. These stars show evidences of being older than the Sun but with a relatively large lithium abundance. We present the seismic analysis of HD42618, and the modeling of the two solar analogs HD42618 andHD43587 using the CESTAM stellar evolution code. Models were computed to reproduce the spectroscopic (effective temperature and metallicity) and seismic (mode frequencies) data,and the luminosity of the stars, based on Gaia parallaxes. We infer very similar values of mass and radius for both stars compared to the literature, within the uncertainties, and reproduce correctly the seismic constraints. For HD42618, the modeling shows it is slightly less massive and older than the Sun. For HD43587, it confirms it is more massive and older than the Sun,in agreement with previous results. The use of chemical clocks improves the reliability of our age estimates.

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arXiv2021

The Flare Likelihood and Region Eruption Forecasting (FLARECAST) Project: Flare forecasting in the big data & machine learning era

The EU funded the FLARECAST project, that ran from Jan 2015 until Feb 2018. FLARECAST had a R2O focus, and introduced several innovations into the discipline of solar flare forecasting. FLARECAST innovations were: first, the treatment of hundreds of physical properties viewed as promising flare predictors on equal footing, extending multiple previous works; second, the use of fourteen (14) different ML techniques, also on equal footing, to optimize the immense Big Data parameter space created by these many predictors; third, the establishment of a robust, three-pronged communication effort oriented toward policy makers, space-weather stakeholders and the wider public. FLARECAST pledged to make all its data, codes and infrastructure openly available worldwide. The combined use of 170+ properties (a total of 209 predictors are now available) in multiple ML algorithms, some of which were designed exclusively for the project, gave rise to changing sets of best-performing predictors for the forecasting of different flaring levels. At the same time, FLARECAST reaffirmed the importance of rigorous training and testing practices to avoid overly optimistic pre-operational prediction performance. In addition, the project has (a) tested new and revisited physically intuitive flare predictors and (b) provided meaningful clues toward the transition from flares to eruptive flares, namely, events associated with coronal mass ejections (CMEs). These leads, along with the FLARECAST data, algorithms and infrastructure, could help facilitate integrated space-weather forecasting efforts that take steps to avoid effort duplication. In spite of being one of the most intensive and systematic flare forecasting efforts to-date, FLARECAST has not managed to convincingly lift the barrier of stochasticity in solar flare occurrence and forecasting: solar flare prediction thus remains inherently probabilistic.

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arXiv2019

New deep coronal spectra from the 2017 total solar eclipse

Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum White-Light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona) and the dust component with F-lines (F-corona). By sufficiently dispersing the W-L spectrum, the Fraunhofer (F) spectrum of the dust component of the corona appears and the continuum Thomson radiation can be evaluated. The superposed emission lines of ions with different degrees of ionization are studied to allow the measurement of temperatures, non-thermal velocities, Doppler shifts and abundances. We describe a slit spectroscopic experiment of high spectral resolution for providing an analysis of the most typical parts of the quasi-minimum type corona observed during the total solar eclipse of Aug. 21, 2017 observed from Idaho, USA. Streamers, active region enhancements and polar coronal holes (CHs) are well measured using deep spectra. 60 spectra are obtained during the totality with a long slit, covering +/-3 solar radii in the range of 510 to 590nm. The K+F continuum corona is well exposed up to 2 solar radius. The F-corona can be measured even at the solar limb. New weak emission lines were discovered or confirmed. The rarely observed high FIP ArX line is recorded almost everywhere; the FeXIV and NiXIII lines are well recorded everywhere. For the first time hot lines are also measured inside the CH regions. The radial variations of the non-thermal turbulent velocities of the lines do not show a great departure from the average values. No significantly large Doppler shifts are seen anywhere in the inner and the middle corona. The wings of the FeXIV line show some non-Gaussianity.

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arXiv2019

The Solar Orbiter SPICE instrument -- An extreme UV imaging spectrometer

The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission. The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument's signal. The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument's design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument's performance. The paper concludes with descriptions of the operations concept and data processing. The performance measurements of the various instrument parameters meet the requirements derived from the mission's science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission.

astro-ph.IM↗

arXiv2018

Amplitude and lifetime of radial modes in red giant star spectra observed by Kepler

Context: the space-borne missions CoRoT and Kepler have provided photometric observations of unprecedented quality. The study of solar-like oscillations observed in red giant stars by these satellites allows a better understanding of the different physical processes occurring in their interiors. In particular, the study of the mode excitation and damping is a promising way to improve our understanding of stellar physics that has, so far, been performed only on a limited number of targets. Aims: the recent asteroseismic characterization of the evolutionary status for a large number of red giants allows us to study the physical processes acting in the interior of red giants and how they are modify during stellar evolution. In this work, we aim to obtain information on the excitation and damping of pressure modes through the measurement of the stars' pressure mode widths and amplitudes and to analyze how they are modified with stellar evolution. The objective is to bring observational constraints on the modeling of the physical processes behind mode excitation and damping. Methods: we fit the frequency spectra of red giants with well defined evolutionary status using Lorentzians functions to derive the pressure mode widths and amplitudes. To strengthen our conclusions, we used two different fitting techniques. Results: pressure mode widths and amplitudes were determined for more than 5000 red giants. With a stellar sample two orders of magnitude larger than previous results, we confirmed that the mode width depends on stellar evolution and varies with stellar effective temperature. In addition, we discovered that the mode width depends on stellar mass. We also confirmed observationally the influence of the stellar metallicity on the mode amplitudes, as predicted by models.

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arXiv2017

PLATO as it is: a legacy mission for Galactic archaeology

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 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 pre-requisite to then reach the more ambitious goal of a similar level of accuracy, which will only be possible if we have to hand a careful appraisal of systematic uncertainties on age deriving from our limited understanding of stellar physics, a goal which conveniently falls within the main aims of PLATO's core science.

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arXiv2016

Red giants observed by CoRoT and APOGEE: The evolution of the Milky Way's radial metallicity gradient

Using combined asteroseismic and spectroscopic observations of 418 red-giant stars close to the Galactic disc plane (6 kpc $<R_{\rm Gal}\lesssim13$ kpc, $|Z_{\rm Gal}|<0.3$ kpc), we measure the age dependence of the radial metallicity distribution in the Milky Way's thin disc over cosmic time. The slope of the radial iron gradient of the young red-giant population ($-0.058\pm0.008$ [stat.] $\pm0.003$ [syst.] dex/kpc) is consistent with recent Cepheid measurements. For stellar populations with ages of $1-4$ Gyr the gradient is slightly steeper, at a value of $-0.066\pm0.007\pm0.002$ dex/kpc, and then flattens again to reach a value of $\sim-0.03$ dex/kpc for stars with ages between 6 and 10 Gyr. Our results are in good agreement with a state-of-the-art chemo-dynamical Milky-Way model in which the evolution of the abundance gradient and its scatter can be entirely explained by a non-varying negative metallicity gradient in the interstellar medium, together with stellar radial heating and migration. We also offer an explanation for why intermediate-age open clusters in the Solar Neighbourhood can be more metal-rich, and why their radial metallicity gradient seems to be much steeper than that of the youngest clusters. Already within 2 Gyr, radial mixing can bring metal-rich clusters from the innermost regions of the disc to Galactocentric radii of 5 to 8 kpc. We suggest that these outward-migrating clusters may be less prone to tidal disruption and therefore steepen the local intermediate-age cluster metallicity gradient. Our scenario also explains why the strong steepening of the local iron gradient with age is not seen in field stars. In the near future, asteroseismic data from the K2 mission will allow for improved statistics and a better coverage of the inner-disc regions, thereby providing tighter constraints on the evolution of the central parts of the Milky Way.

astro-ph.GA↗

arXiv2016

Stellar classification of CoRoT targets

The CoRoT faint stars channel observed about 163 600 targets to detect transiting planetary companions. Because CoRoT targets are faint (11< r <16) and close to the galactic plane, only a small subsample has been observed spectroscopically. We describe the latest classification scheme used to derive the spectral type of CoRoT targets, which is based on broadband multi-colour photometry. We assess the accuracy of this spectral classification for the first time. We find that the classification method performs better for stars that were observed during the mission-dedicated photometric ground-based campaigns.The luminosity class is wrong for less than 7% of the targets. Generally, the effective temperature of stars classified as early type (O, B, and A) is overestimated. Conversely, the temperature of stars classified as later type tends to be underestimated. This is mainly due to the adverse effect of interstellar reddening. We find that the median error on the effective temperature is less than 5% for dwarf stars classified with a spectral later than F0, but it is worse for earlier type stars, with up to 20\% error for A and late-B dwarfs, and up to 70% for early-B and O-type dwarfs. Similar results are found for giants, with a median error that is lower than 7% for G- and later type giants, but greater than 25% for earlier types. Overall, we find an average median absolute temperature difference |Delta Teff| = 533+\-6 K for the whole sample of stars classified as dwarfs and |Delta Teff| = 280+\-3 K for the whole sample of giant stars. The corresponding standard deviation is of about 92+\-5 K for dwarfs and 304+\-4 K for giants. Typically for late-type stars, this means that the classification is accurate to about half a class.

astro-ph.SR↗

arXiv2016

Galactic Archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE

With the advent of the space missions CoRoT and Kepler, it has become feasible to determine precise asteroseismic masses and ages for large samples of red-giant stars. In this paper, we present the CoRoGEE dataset -- obtained from CoRoT lightcurves for 606 red giant stars in two fields of the Galactic disc which have been co-observed for an ancillary project of APOGEE. We have used the Bayesian parameter estimation code PARAM to calculate distances, extinctions, masses, and ages for these stars in a homogeneous analysis, resulting in relative statistical uncertainties of $\sim2\%$ in distance, $\sim4\%$ in radius, $\sim9\%$ in mass and $\sim25\%$ in age. We also assess systematic age uncertainties due to different input physics and mass loss. We discuss the correlation between ages and chemical abundance patterns of field stars over a large radial range of the Milky Way's disc (5 kpc $<R_{\rm Gal}<$ 14 kpc), focussing on the [$α$/Fe]-[Fe/H]-age plane in five radial bins of the Galactic disc. We find an overall agreement with the expectations of chemical-evolution models computed before the present data were available, especially for the outer regions. However, our data also indicate that a significant fraction of stars now observed near and beyond the Solar Neighbourhood migrated from inner regions. Mock CoRoGEE observations of a chemo-dynamical Milky Way disc model show that the number of high-metallicity stars in the outer disc is too high to be accounted for even by the strong radial mixing present in the model. The mock observations also reveal that the age distribution of the [$α$/Fe]-enhanced sequence in the CoRoGEE inner-disc field is much broader than expected from a combination of radial mixing and observational errors. We suggest that a thick disc/bulge component that formed stars for more than 3 Gyr may account for these discrepancies.

astro-ph.GA↗

arXiv2015

Young [$α$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?

We report the discovery of a group of apparently young CoRoT red-giant stars exhibiting enhanced [alpha/Fe] abundance ratios (as determined from APOGEE spectra) with respect to Solar values. Their existence is not explained by standard chemical evolution models of the Milky Way, and shows that the chemical-enrichment history of the Galactic disc is more complex. We find similar stars in previously published samples for which isochrone-ages could be robustly obtained, although in smaller relative numbers, which could explain why these stars have not received prior attention. The young [alpha/Fe]-rich stars are much more numerous in the CoRoT-APOGEE (CoRoGEE) inner-field sample than in any other high-resolution sample available at present, as only CoRoGEE can explore the inner-disc regions and provide ages for its field stars. The kinematic properties of the young [$α$/Fe]-rich stars are not clearly thick-disc like, despite their rather large distances from the Galactic mid-plane. Our tentative interpretation of these and previous intriguing observations in the Milky Way is that these stars were formed close to the end of the Galactic bar, near corotation -- a region where gas can be kept inert for longer times, compared to other regions shocked more frequently by the passage of spiral arms. Moreover, that is where the mass return from older inner-disc stellar generations should be maximal (according to an inside-out disc-formation scenario), further diluting the in-situ gas. Other possibilities to explain these observations (e.g., a recent gas-accretion event) are also discussed.

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arXiv2014

HD 51844: An Am delta Scuti in a binary showing periastron brightening

Pulsating stars in binary systems are ideal laboratories to test stellar evolution and pulsation theory, since a direct, model-independent determination of component masses is possible. The high-precision CoRoT photometry allows a detailed view of the frequency content of pulsating stars, enabling detection of patterns in their distribution. The object HD 51844 is such a case showing periastron brightening instead of eclipses. We present a comprehensive study of the HD 51844 system, where we derive physical parameters of both components, the pulsation content and frequency patterns. Additionally, we obtain the orbital elements, including masses, and the chemical composition of the stars. Time series analysis using standard tools was mployed to extract the pulsation frequencies. Photospheric abundances of 21 chemical elements were derived by means of spectrum synthesis. We derived orbital elements both by fitting the observed radial velocities and the light curves, and we did asteroseismic modelling as well. We found that HD 51844 is a double lined spectroscopic binary. The determined abundances are consistent with delta Delphini classification. We determined the orbital period (33.498 +- 0.002 d), the eccentricity (0.484 +- 0.020), the mass ratio (0.988 +- 0.02), and the masses to 2.0 +- 0.2 M_sun for both components. Only one component showed pulsation. Two p modes (f_22 and f_36) and one g mode (f_orb) may be tidally excited. Among the 115 frequencies, we detected triplets due to the frequency modulation, frequency differences connected to the orbital period, and unexpected resonances (3:2, 3:5, and 3:4), which is a new discovery for a delta Scuti star.

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arXiv2014

The PLATO 2.0 Mission

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0.

astro-ph.EP↗

arXiv2014

Seismic analysis of HD43587Aa, a solar-like oscillator in a multiple system

Context. The object HD 43587Aa is a G0V star observed during the 145-day LRa03 run of the COnvection, ROtation and planetary Transits space mission (CoRoT), for which complementary High Accuracy Radial velocity Planet Searcher (HARPS) spectra with S/N>300 were also obtained. Its visual magnitude is 5.71, and its effective temperature is close to 5950 K. It has a known companion in a highly eccentric orbit and is also coupled with two more distant companions. Aims. We undertake a preliminary investigation of the internal structure of HD 43587Aa. Methods. We carried out a seismic analysis of the star, using maximum likelihood estimators and Markov Chain Monte Carlo methods. Results. We established the first table of the eigenmode frequencies, widths, and heights for HD 43587Aa. The star appears to have a mass and a radius slightly larger than the Sun, and is slightly older (5.6 Gyr). Two scenarios are suggested for the geometry of the star: either its inclination angle is very low, or the rotation velocity of the star is very low. Conclusions. A more detailed study of the rotation and of the magnetic and chromospheric activity for this star is needed, and will be the subject of a further study. New high resolution spectrometric observations should be performed for at least several months in duration.

astro-ph.SR↗

arXiv2013

Differential asteroseismic study of seismic twins observed by CoRoT; Comparison of HD 175272 with HD 181420

The CoRoT short asteroseismic runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report the observation and modeling of the F5V star HD 175272. Our aim is to define a method for extracting as much information as possible from a noisy oscillation spectrum. We followed a differential approach that consists of using a well-known star as a reference to characterize another star. We used classical tools such as the envelope autocorrelation function to derive the global seismic parameters of the star. We compared HD 175272 with HD 181420 through a linear approach, because they appear to be asteroseismic twins. The comparison with the reference star enables us to substantially enhance the scientific output for HD 175272. First, we determined its global characteristics through a detailed seismic analysis of HD 181420. Second, with our differential approach, we measured the difference of mass, radius and age between HD 175272 and HD 181420. We have developed a general method able to derive asteroseismic constraints on a star even in case of low-quality data. %This method is based on the comparison to a star with common seismic and classical properties. Seismic data allow accurate measurements of radii and masses differences between the two stars. This method can be applied to stars with interesting properties but low signal-to-noise ratio oscillation spectrum, such as stars hosting an exoplanet or members of a binary system.

astro-ph.SR↗

arXiv2013

Low-amplitude rotational modulation rather than pulsations in the CoRoT B-type supergiant HD 46769

{We aim to detect and interpret photometric and spectroscopic variability of the bright CoRoT B-type supergiant target HD\,46769 ($V=5.79$). We also attempt to detect a magnetic field in the target.} {We analyse a 23-day oversampled CoRoT light curve after detrending, as well as spectroscopic follow-up data, by using standard Fourier analysis and Phase Dispersion Minimization methods. We determine the fundamental parameters of the star, as well as its abundances from the most prominent spectral lines. We perform a Monte Carlo analysis of spectropolarimetric data to obtain an upper limit of the polar magnetic field, assumping a dipole field.} {In the CoRoT data, we detect a dominant period of 4.84\,d with an amplitude of 87\,ppm, and some of its (sub-)multiples. Given the shape of the phase-folded light curve and the absence of binary motion, we interpret the dominant variability in terms of rotational modulation, with a rotation period of 9.69\,d. Subtraction of the rotational modulation signal does not reveal any sign of pulsations. Our results are consistent with the absence of variability in the Hipparcos light curve. The spectroscopy leads to a projected rotational velocity of 72$\pm 2$\,km\,s$^{-1}$ and does not reveal periodic variability nor the need to invoke macroturbulent line broadening. No signature of a magnetic field is detected in our data. A field stronger than $\sim 500$\,G at the poles can be excluded, unless the possible non-detected field were more complex than dipolar.} {The absence of pulsations and of macroturbulence of this evolved B-type supergiant is placed into context of instability computations and of observed variability of evolved B-type stars.}

astro-ph.SR↗

arXiv2013

Asteroseismic analysis of the CoRoT target HD 169392

The satellite CoRoT (Convection, Rotation, and planetary Transits) has provided high-quality data for almost six years. We show here the asteroseismic analysis and modeling of HD169392A, which belongs to a binary system weakly gravitationally bound as the distance between the two components is of 4250 AU. The main component, HD169392A, is a G0IV star with a magnitude of 7.50 while the second component is a G0V-G2IV star with a magnitude of 8.98. This analysis focuses on the main component, as the secondary one is too faint to measure any seismic parameters. A complete modeling has been possible thanks to the complementary spectroscopic observations from HARPS, providing Teff=5985+/-60K, log g=3.96+/-0.07, and [Fe/H]=- 0.04+/-0.10.

astro-ph.SR↗

arXiv2013

An in-depth study of HD 174966 with CoRoT photometry and HARPS spectroscopy. Large separation as a new observable for δSct stars

The aim of this work was to use a multi-approach technique to derive the most accurate values possible of the physical parameters of the δSct star HD174966. In addition, we searched for a periodic pattern in the frequency spectra with the goal of using it to determine the mean density of the star. First, we extracted the frequency content from the CoRoT light curve. Then, we derived the physical parameters of HD174966 and carried a mode identification out from the spectroscopic and photometric observations. We used this information to look for the models fulfilling all the conditions and discussed the inaccuracies of the method because of the rotation effects. In a final step, we searched for patterns in the frequency set using a Fourier transform, discussed its origin and studied the possibility of using the periodicity to obtain information about the physical parameters of the star. A total of 185 peaks were obtained from the Fourier analysis of the CoRoT light curve, being almost all reliable pulsating frequencies. From the spectroscopic observations, 18 oscillation modes were detected and identified, and the inclination angle ($62.5^{\circ}$$^{+7.5}_{-17.5}$) and the rotational velocity of the star (142 km/s) were estimated. From the multi-colour photometric observations, 3 frequencies were detected, which correspond to the main ones in the CoRoT light curve. We looked for periodicities within the 185 frequencies and found a periodic pattern ~64 μHz. Using the inclination angle, the rotational velocity and an Echelle diagram, showing a double comb outside the asymptotic regime, we concluded that the periodicity corresponds to a large separation structure. The periodic pattern allowed us to discriminate models from a grid, finding that the value of the mean density is achieved with a 6% uncertainty. So, the pattern could be used as a new observable for A-F type stars.

astro-ph.SR↗

arXiv2013

Differential population studies using asteroseismology: solar-like oscillating giants in CoRoT fields LRc01 and LRa01

Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric/spectroscopic constraints, the pulsation spectra of solar-like oscillating giant stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which can be used as proxies for the ages of these evolved stars. In this contribution we provide supplementary material to the comparison we presented in Miglio et al. (2013) between populations of giants observed by CoRoT in the fields designated LRc01 and LRa01.

astro-ph.SR↗