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First Attempt of Modelling of the COROT Main Target HD 49434

First Attempt of Modelling of the COROT Main Target HD 49434. Workshop: "gamma Doradus stars in the COROT fields" 26 - 28/05/2008 - Nice Mehdi – Pierre BOUABID Laboratoire Fizeau (OCA/UNSA/CNRS) ‏. Context of the study Already done

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First Attempt of Modelling of the COROT Main Target HD 49434

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  1. First Attempt of Modelling of theCOROT Main TargetHD 49434 Workshop: "gamma Doradus stars in the COROT fields" 26 - 28/05/2008 - Nice Mehdi – Pierre BOUABID Laboratoire Fizeau (OCA/UNSA/CNRS)‏

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

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

  4. Teff = 7300 ± 200 K ; log(g) = 4.2 ± 0.4 (Bruntt et al. 2004)‏ Teff = 7632 ± 126 K ; log(g) = 4.43 ± 0.2 (Gillon & Magain 2006)‏ log(L/L ) = 0.825 ± 0.022 (SIMBAD Catalog)‏ [Fe/H] = - 0.04 ± 0.21 (Bruntt et al. 2004)‏ [Fe/H]= + 0.09 ± 0.07 (Gillon & Magain 2006)‏ Z = 0.019 ± 0.002 (Uytterhoeven et al. 2008) v.sin(i) = 85.4 ± 6.6 km.s-1 (Gillon et Magain 2006)‏ Stellar parameters of HD 49434

  5. What is the best way to find the stellar parameters of HD 49434 ? - 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 (Hα depends on Teff)  Bruntt et al. (2004) - multi-line spectroscopy  Gillon et Magain (2006) Photometry vs Spectroscopyfor stellar parameters calculation

  6. Results from the ground-based observations Frequencies (c/d) Uncertain Frequencies (c/d)‏ 0.234185(7) ??? 6.6841/7.6841 1.2732(8) 10.1527/9.1527 1.4831(8) 12.0332/11.0332 1.734820(5) 2.666(2) 5.3311(3) 5.583(1) 9.3070(3) γDor δSct

  7. CLES : « Code Liégeois d’Évolution Stellaire » v.18 LOSC : adiabatic oscillation code v.37 at term MAD : non adiabatic oscillation code First modelling of HD 49434

  8. 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

  9. 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 CLES !

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

  11. - 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; 0.02 - αConv = 2.0 First grid of models

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

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

  14. γDor excitation mechanism temperature interval Teff (HD 49434)

  15. 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 = Results

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

  17. M = 1.80 Mo αconv = 3.0 Z = 0.01 Z = 0.02 for αconv = 2.0 !!! M = 1.30 Mo

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

  19. αconv = 3.0 γDor excitation mechanism temperature interval Teff (HD 49434)

  20. 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

  21. MAD Dupret & Grigahcène – private communication

  22. Guzik’s criterion ???

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

  24. Work in progress ! Thank you !

  25. 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 adiabatic pulsation code

  26. - 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 LOSC outputs

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