WP120 Organisational chart

PSM WP 120000

Title: Stellar Science coordination
Leader: M.J. Goupil
Office: K. Belkacem, R-M Ouazzani, T. Morel and C. Rénié
Objectives: Coordination of the work packages WP121000 to WP129000.

PSM WP 121000

Title: Stellar modeling
Leader: A. Serenelli
Objectives: Coordination of works from work packages WP 121 100 to WP 121 500.

1. Provide grids of state-of-the-art stellar models produced by selected, accurate and tested stellar evolution codes along with their pulsation frequencies (WP 121 100);
2. Establish a set of stellar objects (clusters, binaries) as test cases for the grid code(s) (WP 121 100)
3. Develop improved descriptions for the constitutional physics of stars from multi-dimensional simulations of rotation and convection (WP 121 400) and the influence of binarity (WP 121 500) with specific emphasis on mixing processes inside stars and the effect on pulsational properties;
4. Implement these improved descriptions in a 1-D stellar evolution including rotation (WP 121 200 and WP 121 300);
5. Provide a second generation of updated stellar models (WP 121 100, WP 121 200, WP 121 300) with such an improved code including these new descriptions;
6. Test these improvements with available (CoRoT and Kepler) data 7.Finally provide a third and final grid of models including all of the above

PSM WP 120200

Title: WP120 performances
Leader: M. Deal & R. Samadi
Objectives: Evaluation of the performances of the stellar pipeline specified by the WP120

PSM WP 121100

Title: 1D Stellar models
Leader: Y. Lebreton
Objectives: To provide grids of high quality 1D stellar models and an automated evolutionary code specifically adapted to low mass, main sequence stars

PSM WP 121110

Title: Grids of stellar models
Leader: J. Montalban
Objectives: Provide grids of high quality 1D stellar models for low mass, main sequence stars.

PSM WP 121120

Title: Theoretical oscillation frequencies
Leader: J. C. Suarez
Objectives: Provide theoretical oscillation spectra for 1D stellar models for low mass, main sequence stars

PSM WP 121200

Title: Transport processes
Leader: A. Palacios
Objectives: To model several transport processes, beyond classical convective heat transport, that are known or expected to play an important role in determining stellar structure and influence stellar evolution. Formulations for transport of heat, chemical elements and angular momentum induced by motions such as convection, rotation, turbulence or waves will be improved or developed with the objective of implementation in a 1D stellar evolutionary code.

PSM WP 121300

Title: M dwarfs
Leader: S. Cassisi
Objectives: To provide an extended and updated grid of state-of-the-art evolutionary models for stellar structures in the Very Low Mass Stars regime (M<0.5 solar mass) for any specified chemical composition. These models will be computed from the Pre-Main Sequence to the Main Sequence.

PSM WP 121400

Title: PMS evolution
Leader: J. P. Marques
Objectives: To build a computation tool that provides PMS stellar models with rotation profiles and initial conditions as realistic as possible.

PSM WP 121500

Title: 2D/3D Stellar evolution models
Leader: M. Rieutord
Objectives: The objective of the WP is to deliver very precise 2D stellar models. Indeed, the determination of the bulk parameter of a star (Age, Mass, etc.) from seismic data needs a very good
preliminary model of the star. Such good models require at least two spatial dimensions to properly include the effects of rotation. We therefore propose to deliver models at the state-of-the-art level, which can be combined to the best oscillations codes out of which the most precise stellar parameters can be drawn.

PSM WP 121600

Title: Binarity
Leader: S. Mathis
Objectives: The first objective of this WP is to deliver advanced models of tidal, MHD, and accretion torques applied to stars hosting planetary or/and stellar companions. Second, the modification of their rotational and chemical evolution because of the presence of a companion will be studied using ab-initio models for internal transport mechanisms and applied torques. The corresponding new generation of stellar evolution models will be delivered as well as the corresponding seismic diagnosis.

PSM WP 122000

Title: Non seismic diagnostics and model atmospheres
Leader: T. Morel
Objectives: Develop new generations of state-of-the-art 1D/3D stellar model atmospheres and compute improved grids of limb-darkening coefficients. Specify procedures for an accurate determination of the fundamental parameters (e.g., Teff, radii, and chemical abundances) based on non-seismic diagnostics (e.g., ground-based data, Gaia parallaxes). Coordinate activities of WP 122100 to WP 122500.

PSM WP 122100

Title: 1D model atmospheres
Leader: B. Plez
Objectives: Improve our knowledge of stellar photospheres for PLATO targets (i.e., FGK dwarfs and subgiants, M dwarfs). Ensure that we have the best possible description of their atmospheres, necessary for the accurate characterisation of their output spectra, limb-darkening, and internal structure boundary condition. Provide the grid of model atmospheres to be used for the analysis of PLATO data.
Key personal: B. Plez (LUPM), and Paul Barklem, Bengt Edvardsson, Kjell Eriksson, Ulrike Heiter, Oleg Kochukhov, Terese Olander and Nikolai Piskunov (University of Uppsala)

PSM WP 122200

Title: 3D model atmospheres
Leader: R. Collet
Objectives: Develop 3D hydrodynamical stellar model atmospheres of late-type stars (spectral type FGKM, dwarfs and subgiants) for a wide range of stellar parameters (effective temperature, surface
gravity, metallicity) targeted by PLATO. Continuously improve 3D model atmospheres to ensure highest accuracy and reliability in derived stellar parameters and chemical compositions.

PSM WP 122300

Title: Fundamental stellar parameters
Leader: C. Allende Prieto
Objectives: Assess the limitations and accuracy of the different methods to determine fundamental stellar parameters (Teff, BC, radius, chemical abundances, etc.) for FGKM stars observed by PLATO, based on photometric and spectroscopic observations, including astrometry to be provided by Gaia. Identify the preferred protocol to derive fundamental parameters and chemical abundances for targets of interest. Provide model fluxes covering the parameter space of the FGKM stars observed by PLATO.

PSM WP 122400

Title: Limb-darkening
Leader: A. Claret
Objectives: Determine with precision the limb-darkening distribution of the host stars. Identify and quantify the sources of uncertainties in masses, radii and effective temperatures of the host stars due to limb-darkening.

PSM WP 122500

Title: Interstellar extinction
Leader: D. Marshall
Objectives: Provide values of anticipated extinction along different lines of sight. Ensure that interstellar extinction is handled properly to enable precision estimates of stellar parameters.

PSM WP 123000

Title: Stellar activity and rotation
Leader: A.F. Lanza
Objectives: a) To measure the level of stellar magnetic activity, the rotation period, and the latitudinal differential rotation. They will be input to modeling of stellar structure and evolution, stellar atmospheres, and hydromagnetic dynamo action; b) to predict magnetic field effects on stellar eigenfrequencies; c) to predict the radial velocity perturbations arising from magnetic perturbations of surface convection and photospheric brightness inhomogeneities this is of fundamental importance to confirm telluric planets and measure their mass. The measure of the rotation period, in combination with models of stellar angular momentum evolution, can be used to estimate the age of planet-hosting stars in the field through the methods of gyro-chronology. A knowledge of stellar rotation is fundamental also to study tidal effects in planetary systems with close-in planets. The level of stellar magnetic activity controls the photo-evaporation of the
atmosphere of close-in planets and the space weather in planetary systems having late-type stars with winds coming from magnetically controlled coronae.

PSM WP 123100

Title: Spot models
Leader: N. Meunier
Objectives: To provide methods and algorithms for the measurement of spot distributions, in close relation with the stellar activity (WP123000)

PSM WP 123200

Title: Surface convection (1D-3D)
Leader: F. Kupka
Objectives: This WG must provide information on the properties of surface activity of the host stars. In particular, it is dedicated to determine the properties of surface convection (granulation,) in function of the spectral type using both 3D numerical simulations and 1D models of convection.

PSM WP 123300

Title: Model of rotational evolution and gyrochronology
Leader: M. Pinsonneault
Objectives: Testing of theoretical models of stellar angular momentum loss, internal angular momentum transport, and the associated mixing. There are two distinct applications: understanding of stellar physics and applications to stellar population studies. Examples of the former would include asteroseismic tests of dynamo models and distinguishing between magnetic, wave-driven, and hydrodynamic transport processes in stellar interiors. Examples of the latter would include exploring rotation as an age indicator for low mass stars and synthesizing connections between stellar activity (chromospheric and coronal), rotation, age, and mass for habitability studies.

PSM WP 123400

Title: Dynamos and differential rotation
Leader: A.S. Brun
Objectives: Most stars rotate and exhibit a large diversity of magnetic fields. It is believed that dynamo action, i.e the complex, nonlinear interplay between, convection, large scale flows (differential rotation and meridional circulation) and magnetic fields, is the source of the magnetism of solar like stars and M dwarfs, the main stellar targets of PLATO. Being able to constrain all these MHD processes is crucial to our understanding of stars and their impact on their environment. Seismic inversions of the extent of convective envelope, the surface and internal profiles of large scale flows and of proxies of the magnetic activity will help reaching this goal.

PSM WP 123500

Title: Tools to measure rotational modulation
Leader: S. Messina
Objectives: To derive the stellar rotation period from the stellar flux rotational modulation. The latter is induced either by surface temperature inhomogeneities that are carried in and out of view by the stellar rotation or eclipses in close binary systems. Different algorithms (e.g., Fourier-based methods, phase dispersion minimization, amplitude of variance) will be used to analyze the photometric time series, to assign a quality flag to each inferred rotation period, and to estimate their confidence level. Possible rotation period variations related to surface differential rotation will be also investigated.

PSM WP 123600

Title: Stellar rotation from transits
Leader: A. Silva-Valio
Objectives: Modelling of starspots occulted by the planet during its transits and estimate of the rotation rate at the occulted latitude using starspots as tracers. In combination with the out-of-transit light curve modelling, this allows us to estimate stellar differential rotation.

PSM WP 124000

Title: Seismic diagnostics
Leader: M. Cunha
Objectives: To deliver inverse and forward procedures to the PDC and associated validated numerical codes which are able to provide precise mass, age radius and other information on the host stars.

PSM WP 124100

Title: Forward approaches
Leader: I. Roxburgh
Objectives: To test and compare forward procedures that can deliver total mass, radius, age, and other information on the host stars. The adopted procedures will focus on low mass, main sequence stars from F to M spectral types.

PSM WP 124200

Title: Inverse techniques
Leader: D. Reese
Objectives: To develop inverse methods that can provide total mass, internal density profile and other information on the host stars, The adopted procedures will focus on low mass, main sequence stars from F to M spectral types.

PSM WP 124300

Title: Glitches
Leader: S. Deheuvels
Objectives: To develop methods based on glitches that can provide total mass, internal density profile and other information on the host stars, The adopted procedures will focus on low mass, main sequence stars from F to M spectral types.

PSM WP 125000

Title: Determination of stellar parameters
Leader: J. Christensen-Dalsgaard
Objectives: Coordinate the definition of the work in WP 125100, 125200, 125300 and 125400, such that it will result in the establishment of procedures to determine masses, radii, composition and other relevant properties with a precision required by the exoplanet WPs. Maintain close coordination with the activities under WP 121000 (Stellar models) to ensure that reliable modelling tools will be available for use in the analysis of the data. Maintain close coordination with WP122000 to ensure that optimal modelling tools will be available for use for determination of ’classical’ parameters under WP125200.

PSM WP 125100

Title: Scaling laws
Leader: A. Miglio
Objectives: Provide procedures to compute mass, radius, and other relevant quantities from asteroseismic and non-asteroseismic data, through the application of scaling laws and other relevant relations between the observed quantities, in particular frequencies and power distribution, and the stellar properties. This must include procedures for full statistical analysis,allowing determination of error properties of the inferred quantities.

PSM WP 125200

Title: Classical parameters
Leader: S. Feltzing
Objectives: Prepare procedures to incorporate reliable information about classical stellar properties in the analysis to determine stellar parameters. These properties include effective temperature, luminosity, radius, composition from ground-based photometry and spectroscopy and, in particular, from the Gaia observations, expected to be available when PLATO is launched. The analysis must include use of optimal stellar atmosphere modelling for the interpretation of the observations. Procedures must be included for full statistical analysis, allowing determination of error properties of the inferred quantities.

PSM WP 125300

Title: Seismic Parameters
Leader: C. Karoff
Objectives: Based on procedures from 125100 and 125200, combine the results in procedures to determine the desired properties of the stars (mass, radius, age, composition, ...) in an optimal fashion, including also a study of the benefit of including individual frequencies in the analysis. Procedures must be included for full statistical analysis, allowing determination of error properties of the inferred quantities. As a side benefit, information should be extracted which documents, in a statistically solid fashion, errors in the underlying stellar models, to be used in updating the modelling and hence reducing the systematic errors in the inferred stellar parameters.

PSM WP 125400

Title: Open Clusters
Leader: S. Basu
Objectives: Based on procedures from WP125100 and WP125200, and using input from WP125300, identify and develop the procedures that make use of the specific information provided from the fact that stars are members of open clusters. This includes specific requirements on the ’classical’ information under WP125200. Procedures must be included for full statistical analysis, allowing determination of error properties of the inferred quantities. As a side benefit, information should be extracted which documents, in a statistically solid fashion, errors in the underlying stellar models, to be used in updating the modelling and hence reducing the systematic errors in the inferred stellar parameters, noting that internal consistency amongst cluster stars may be particularly relevant for this.

PSM WP 125500

Title: Benchmark stars
Leader: Orlagh Creevey
Objectives: Gather a set of extremely well characterized stars in order to test the stellar parameters determination pipelines: Gaia Benchmark stars, Eclisping binaries, etc...
Members: Pierre Maxted, Patrick Gaulme, Sydney Barnes, Jose Diaz de Nascimiento

PSM WP 126000

Title: Mode Physics
Leader: J. Ballot
Objectives: The mode physics WP126000 to WP126400 are designed to provide realistic determinations of mode amplitudes and line-widths, in relation with WP123000. The objectives are to provide realistic stellar lightcurves including oscillations as well as an estimation and modeling of sub-surface effects (e.g. turbulent pressure, granulation, magnetic effects) on mode parameters. These developments will benefit from the CoRoT and KEPLER legacy.

PSM WP 126100

Title: Mode amplitude and surface effects on mode parameters
Leader: R. Samadi
Objectives: The first objective is to prepare and provide effcient tools that give us access to a realistic determination of mode amplitudes across the HR-diagram by using semi-analytical modeling as well as 3D hydrodynamic simulations. Using CoRoT and Kepler observations will test
the results. The second objective is to investigate one specific contribution to what is commonly called surface e effects, e.g. the effect of turbulent pressure.

PSM WP 126200

Title: Mode line-width
Leader: M.A. Dupret
Objectives: This WP aims to improve the theoretical determination of mode line-width. A quantitative estimation of mode line-widths of solar-like stars across the HR diagram will be provided. It is an important objective since the line-width determines the mode detectability.

PSM WP 126300

Title: Relation Intensity-Velocity
Leader: G. Houdek
Objectives: Relation between mode Intensity and velocity: the CoRoT mission taught us that a correct modeling of mode amplitude and line-width is not sufficient to reproduce the observations. Indeed, the ratio between mode intensity (luminosity) and velocity amplitudes is also needed. To progress on the knowledge of this ratio, dominated by non-adiabatic effects, ground-based spectroscopic as well as photometric observations are needed on the same targets. In addition, this work package aims to investigate the effect of adopting various stellar atmospheres on the superadiabatic outer stellar layers and consequently mode amplitude ratios.

PSM WP 126400

Title: Seismology of magnetic activity
Leader: L. Gizon
Objectives: The main objective is to characterize and parameterize the influence of magnetic field on mode parameters.

PSM WP 127 000

Title: Seismic constraints from ageing stars
Leader: B. Mosser
Objectives: This WP aims at coordinating the activities of stellar modelling and seismic tools specific for the case of evolved stars. This concerns first exoplanets orbiting red giants stars, but also procedures that constraints stellar evolution for strengthening the properties of stars hosting planets at all evolutionary stages.

PSM WP 127 100

Title: Stellar models of evolved stars
Leader: P. Ventura
Objectives: Provide grids of high quality 1D stellar models for low and intermediate mass in the phases of red giant branch (RGB) and core He-burning (He-B). These grids are an extension of those delivered by WP 121 100 for a reduced set of stellar parameters and lower precision than that required for main sequence models. The domain of mass and age will be determined by the constraints provided by the age of the universe and the maximum luminosity for exo-planet transit detection in the framework of PLATO.

PSM WP 127 200

Title: Seismic diagnostics for evolved stars
Leader: A. Miglio
Objectives: To develop seismic diagnostics specific to evolved stars that can provide precise stellar mass, age, radius and properties of the stellar interior. This objective has three applications: providing accurate stellar parameters for planetary host stars, understanding of stellar physics, and characterising stellar populations monitored by PLATO. These developments build upon the CoRoT, Kepler, and K2 legacy.

PSM WP 127 300

Title: Constraints on main-sequence stars
Leader: J. Montalban
Objectives: Deriving constraints on main-sequence stars hosting planets from the comprehensive study of the observations of stellar populations including all evolutionary stages

PSM WP 128 000

Title: Power spectrum fitting tools
Leader: W.J. Chaplin
Objectives: Coordination of the workpackages WP128100 through WP128250, which deal with the application of data analysis techniques — in particular "peak bagging" — to the frequency-power spectra of the lightcurves, in order to extract estimates of the seismic parameters.

PSM WP 128 100

Title: Average seismic parameters
Leader: R. Garcia
Objectives: To specify requirements and procedures for the estimation of average seismic parameters for solar-type stars. These data will be used to provide asteroseismic stellar properties estimates which will be final estimates where no further detailed "peak bagging" analysis for
individual modes is possible (low SNR targets); or serve as preliminary estimates if further detailed modelling, using individual frequencies, is performed. These average parameters will also be crucial as prior inputs for the peak-bagging analyses.

PSM WP 128 200

Title: Mode fitting tools
Leader: W.J. Chaplin
Objectives: Coordination of the workpackages WP128210 through WP128240 which are devoted to peak-bagging, i.e., estimation of the seismic parameters on individual modes.

PSM WP 128 210

Title: Solar-like stars
Leader: Chaplin (UoB)
Objectives: Specify optimal requirements, techniques and procedures for peak-bagging solar-type stars.

PSM WP 128 220

Title: Solar-like stars with planets
Leader: T. Campante
Objectives: Specify additional requirements and procedures when peak-bagging planet hosts (e.g., requirements on preparation of the data so that signatures of the transits do not interfere with the fitting of the modes, including estimation of intrinsic stellar sources of broad-band background power).

PSM WP 128 230

Title: Multiple Stars
Leader: G.R. Davies
Objectives: Specify additional techniques and procedures for fitting stars in known binaries, i.e., to leverage the additional prior constraints available in such systems, in particular "seismic binaries" where the power spectra of two physically associated stars are detected in the frequency-power spectrum of the same lightcurve.

PSM WP 128 240

Title: Ensemble Fit
Leader: J. Ballot
Objectives: Specify additional techniques and procedures for fitting stars in clusters, i.e., to leverage the additional prior constraints available on such stars.

PSM WP 128 250

Title: Red Giants
Leader: S. Hekker
Objectives: Specify special techniques and procedures needed to extract seismic parameters on the oscillations of red giant stars.

PSM WP 128300

Title: Lightcurve preparation for asteroseismology
Leader: A. Moya
Objectives: Preparation of the asteroseismic-analysis-ready lightcurves from L1 data

PSM WP 129 000

Title: Interfaces to PDC, PSM WPs and public outreach
Leader: R- M. Ouazzani
Objectives: Interface between Stellar Science and other WPs, specifically PDC and Exoplanet WPs.

PSM WP 129 100

Title: Interfaces to PDC, PSM WPs
Leader: R- M. Ouazzani
Objectives: Interface between Stellar Science and other WPs, specifically PDC and Exoplanet WPs.

PSM WP 129 200

Title: Public outreach
Leader: F. Baudin
Objectives: Provide public outreach material : press releases and dissemination