First Attempt of Modelling of the COROT Main Target HD Workshop: "gamma Doradus stars in the COROT fields" /05/ Nice Mehdi – Pierre BOUABID Laboratoire Fizeau (OCA/UNSA/CNRS) ‏

Outline of the Talk Context of the study Context of the study Already done Already done Stellar parameters Stellar parameters Results of ground-based observations Results of ground-based observations Modelling Modelling Tools Tools Grid of models Grid of models Results Results Future work with the oscillation codes Future work with the oscillation codes Conclusions & prospects Conclusions & prospects

Context of this study - γDor F1V - Primary Target of the COROT winter 2007 long run - Ground-based observations during winter 2006 & winter Theoretical study makes with help from M.-A. Dupret, A. Grigahcène, A. Miglio, J. Montalban, A. Noels.

Stellar parameters of HD T eff = 7300 ± 200 K ; log(g) = 4.2 ± 0.4 (Bruntt et al. 2004)‏ T eff = 7632 ± 126 K ; log(g) = 4.43 ± 0.2 (Gillon & Magain 2006)‏ log(L/L  ) = ± (SIMBAD Catalog)‏ [Fe/H] = ± 0.21 (Bruntt et al. 2004)‏ [Fe/H] = ± 0.07 (Gillon & Magain 2006)‏ Z = ± (Uytterhoeven et al. 2008) v.sin(i) = 85.4 ± 6.6 km.s -1 (Gillon et Magain 2006)‏

Photometry vs Spectroscopy for stellar parameters calculation What is the best way to find the stellar parameters of HD ? - mesure of the photometric flux : need data from UV to IR  no UV data available - using the photometric parameters (b-y,m1,c1,beta)‏  Bruntt et al. (2004) - spectroscopic study of one line (H α depends on T eff )  Bruntt et al. (2004) - multi-line spectroscopy  Gillon et Magain (2006)

Results from the ground-based observations Frequencies (c/d)Uncertain Frequencies (c/d)‏ (7)???6.6841/ (8) / (8) / (5)2.666(2)5.3311(3)5.583(1)9.3070(3) γDor δSct

First modelling of HD CLES : « Code Liégeois d’Évolution Stellaire » v.18 LOSC : adiabatic oscillation code v.37 at term MAD : non adiabatic oscillation code

CLES Young interactive stellar evolution code, still in development by the Liege Team and associates Generate evolutionary sequence of models from the Hayashi Track to the He Flash

CLES Parameters in CLES : - mixing length - overshooting - diffusion - equation of state - mass - metallicity/opacity table - hydrogen and metal fraction Many inputs  Need a good accuracy of observed stellar parameters !

Limits of CLES This version of CLES does not take into account : - radiative accelerations - undershooting at the base of the convective envelope - rotation - mass loss …

First grid of models - EOS Opal - Standard metallicity and opacity tables (Grevesse Noels 1993)‏ Grid : - M = 1.30 to 1.80 M  by step of 0.05 M  ‏ - Z = 0.01; α Conv = 2.0

M = 1.30 Mo Z = 0.01 Z = 0.02 M = 1.80 Mo

Mo M = 1.80 Mo M = 1.30 Mo γDor excitation mechanism temperature interval (*) (*) Guzik et al. (2000) Z = 0.01 Z = 0.02

γDor excitation mechanism temperature interval T eff (HD 49434)

Results It is not easy to generate models showing γDor excitation mechanism characteristics at this temperature Convection efficiency depends on the temperature : Convection ∇ rad > ∇ ad with ∇ rad =

Try to see with a α conv = 3.0 α conv = 3.0 α conv = L/H p is a free parameter - L = Mean free path of a globule in the convective zone - H p = Pressure scale α conv  = 1.8 Hydrodynamics 2D & 3D simulations show that we expect : when T eff , α conv   How can we explain a so efficient convection ?

M = 1.30 Mo M = 1.80 Mo Z = 0.01 Z = 0.02 α conv = 3.0 for α conv = 2.0 !!!

M = 1.30 Mo M = 1.80 Mo γDor excitation mechanism temperature interval (*) Guzik et al. (2000) γDor excitation mechanism temperature interval (*) (*) Guzik et al. (2000) α conv = 3.0 Z = 0.02 Z = 0.01

α conv = 3.0 γDor excitation mechanism temperature interval T eff (HD 49434)

With LOSC, we can see if p and g modes can exist for this models BUT We can not learn anything more from adiabatic pulsation modelling  Need non-adiabatic study to see if γDor/δSct oscillations can be excited for this models

MAD Dupret & Grigahcène – private communication

Guzik’s criterion ???

Conclusions & Prospects Challenging star to modelise Challenging star to modelise Need more restrained stellar parameters (with our own data ?!) Need more restrained stellar parameters (with our own data ?!) Need a non-adiabatic seismic study Need a non-adiabatic seismic study Will be helped by a study of the Liège γDor models grid Will be helped by a study of the Liège γDor models grid Constrain the blue edge of the γDor IS Constrain the blue edge of the γDor IS Learn more about the γDor excitation mechanism Learn more about the γDor excitation mechanism Learn more about γDor/δSct hybrid pulsators Learn more about γDor/δSct hybrid pulsators

Work in progress ! Thank you !

LOSC adiabatic pulsation code Inputs : - choice of the grid step to compute oscillations - optimal distribution of points for p or g modes - scan - frequency spectrum - equidistant scale in frequency (p modes) or in time (g modes)‏ - calculation of modes for an approximative frequency

LOSC outputs - degree of the mode - order of the mode - parity of the mode - (non-)dimensional frequency - vertical energy fraction versus total energy - Eigenfunctions of the mode