First Attempt of First Attempt of Modelling of theModelling of the

COROT Main TargetCOROT Main TargetHD 49434HD 49434

Workshop: "gamma Doradus stars in the COROT fields"

26 - 28/05/2008 - Nice Mehdi – Pierre BOUABID

Laboratoire Fizeau (OCA/UNSA/CNRS)

Outline of the TalkOutline of the Talk

Context of the studyContext of the study Already doneAlready done

Stellar parametersStellar parameters Results of ground-based observationsResults of ground-based observations

ModellingModelling ToolsTools Grid of modelsGrid of models ResultsResults Future work with the oscillation codesFuture work with the oscillation codes

Conclusions & prospectsConclusions & prospects

Context of this studyContext of this study

- γDor F1V- γDor F1V

- Primary Target of the COROT winter 2007 long run- Primary Target of the COROT winter 2007 long run

- Ground-based observations during winter 2006 & winter 2007- Ground-based observations during winter 2006 & winter 2007

- Theoretical study makes with help from M.-A. Dupret, A. - Theoretical study makes with help from M.-A. Dupret, A.

Grigahcène, A. Miglio, J. Montalban, A. Noels.Grigahcène, A. Miglio, J. Montalban, A. Noels.

Stellar parameters of Stellar parameters of HD 49434HD 49434

TTeffeff = 7300 ± 200 K ; log(g) = 4.2 ± 0.4 (Bruntt et al. 2004) = 7300 ± 200 K ; log(g) = 4.2 ± 0.4 (Bruntt et al. 2004)

TTeffeff = 7632 ± 126 K ; log(g) = 4.43 ± 0.2 (Gillon & Magain 2006) = 7632 ± 126 K ; log(g) = 4.43 ± 0.2 (Gillon & Magain 2006)

log(L/L log(L/L ) = 0.825 ± 0.022 (SIMBAD Catalog)) = 0.825 ± 0.022 (SIMBAD Catalog)

[Fe/H] = - 0.04 ± 0.21 (Bruntt et al. 2004)[Fe/H] = - 0.04 ± 0.21 (Bruntt et al. 2004)

[Fe/H][Fe/H] = + 0.09 ± 0.07 (Gillon & Magain 2006)= + 0.09 ± 0.07 (Gillon & Magain 2006)

Z = 0.019 ± 0.002 (Z = 0.019 ± 0.002 (UytterhoevenUytterhoeven et al. 2008) et al. 2008)

v.sin(i) = 85.4 ± 6.6 km.sv.sin(i) = 85.4 ± 6.6 km.s-1-1 (Gillon et Magain 2006) (Gillon et Magain 2006)

Photometry vs Photometry vs SpectroscopySpectroscopy

for stellar parameters for stellar parameters calculationcalculation

What is the best way to find the stellar parameters of HD 49434 ?What is the best way to find the stellar parameters of HD 49434 ?

- mesure of the photometric flux : need data from UV to IR - mesure of the photometric flux : need data from UV to IR

no UV data availableno UV data available

- using the photometric parameters (b-y,m1,c1,beta)- using the photometric parameters (b-y,m1,c1,beta) Bruntt et al. Bruntt et al. (2004)(2004)

- spectroscopic study of one line (H- spectroscopic study of one line (Hαα depends on T depends on Teffeff) ) Bruntt et Bruntt et

al. (2004)al. (2004)

- multi-line spectroscopy - multi-line spectroscopy Gillon et Magain (2006) Gillon et Magain (2006)

Results from the ground-Results from the ground-based observationsbased observations

Frequencies (c/d)Frequencies (c/d) Uncertain Frequencies (c/d)Uncertain Frequencies (c/d)

0.234185(7)0.234185(7) ?????? 6.6841/7.68416.6841/7.6841

1.2732(8)1.2732(8) 10.1527/9.152710.1527/9.1527

1.4831(8)1.4831(8) 12.0332/11.033212.0332/11.0332

1.734820(5) 1.734820(5)

2.666(2) 2.666(2)

5.3311(3) 5.3311(3)

5.583(1) 5.583(1)

9.3070(3) 9.3070(3)

γDor

δSct

First modelling of First modelling of HD 49434HD 49434

CLES : « Code Liégeois d’Évolution Stellaire » v.18CLES : « Code Liégeois d’Évolution Stellaire » v.18

LOSC : adiabatic oscillation code v.37LOSC : adiabatic oscillation code v.37

at term MAD : non adiabatic oscillation codeat term MAD : non adiabatic oscillation code

CLESCLES

Young interactive stellar evolution code, still in development by the Young interactive stellar evolution code, still in development by the Liege Team and associatesLiege Team and associates

Generate evolutionary sequence of models from the Hayashi Track Generate evolutionary sequence of models from the Hayashi Track to the He Flashto the He Flash

CLESCLESParameters in CLES :Parameters in CLES :

- mixing length- mixing length

- overshooting- overshooting

- diffusion- diffusion

- equation of state- equation of state

- mass- mass

- metallicity/opacity table- metallicity/opacity table

- hydrogen and metal fraction- hydrogen and metal fraction

Many inputs Many inputs Need a good accuracy of observed stellar Need a good accuracy of observed stellar

parametersparameters

!

Limits of CLESLimits of CLES

This version of CLES does not take into account :This version of CLES does not take into account :

- radiative accelerations- radiative accelerations

- undershooting at the base of the convective envelope- undershooting at the base of the convective envelope

- rotation- rotation

- mass loss …- mass loss …

First grid of models First grid of models

- EOS Opal- EOS Opal

- Standard metallicity and opacity tables (Grevesse Noels 1993)- Standard metallicity and opacity tables (Grevesse Noels 1993)

Grid :Grid :

- M = 1.30 to 1.80 M- M = 1.30 to 1.80 M by step of 0.05 M by step of 0.05 M

- Z = 0.01; 0.02- Z = 0.01; 0.02

- α- αConvConv = 2.0 = 2.0

M = 1.30 Mo

Z = 0.01

Z = 0.02

M = 1.80 Mo

Mo

M = 1.80 MoM = 1.80 Mo

M = 1.30 MoM = 1.30 Mo

γγDor excitation mechanism temperature interval Dor excitation mechanism temperature interval (*)(*)

(*) Guzik et al. (2000)(*) Guzik et al. (2000)

Z = 0.01Z = 0.01

Z = 0.02Z = 0.02

γγDor excitation mechanism temperature intervalDor excitation mechanism temperature interval

TTe

ffeff (

HD

494

34)

(H

D 4

9434

)

ResultsResultsIt is not easy to generate models showing γDor excitation It is not easy to generate models showing γDor excitation mechanism characteristics at this temperaturemechanism characteristics at this temperature

Convection efficiency depends on the temperature :Convection efficiency depends on the temperature :

Convection Convection ∇∇radrad > > ∇∇adad

with with ∇∇radrad = = 4T

P

acGm16

L3

Try to see with a Try to see with a ααconvconv = = 3.03.0

ααconvconv = 3.0 = 3.0

ααconvconv = L/H = L/Hpp is a free parameter is a free parameter

- L = Mean free path of a globule in the convective zone- L = Mean free path of a globule in the convective zone

- H- Hpp = Pressure scale = Pressure scale

ααconv conv = 1.8= 1.8

Hydrodynamics 2D & 3D simulations show that we expect :Hydrodynamics 2D & 3D simulations show that we expect :

when Twhen Teffeff , α, αconvconv

How can we explain a so efficient convection ?How can we explain a so efficient convection ?

M = 1.30 Mo

M = 1.80 Mo

Z = 0.01

Z = 0.02

ααconvconv = 3.0 = 3.0

for αconv = 2.0 !!!

M = 1.30 Mo

M = 1.80 Mo

γγDor excitation mechanism temperature intervalDor excitation mechanism temperature interval

(*) Guzik et al. (2000)(*) Guzik et al. (2000)

γγDor excitation mechanism temperature interval Dor excitation mechanism temperature interval (*)(*)

(*) Guzik et al. (2000)(*) Guzik et al. (2000)

ααconvconv = 3.0 = 3.0

Z = 0.02Z = 0.02

Z = 0.01Z = 0.01

ααconvconv = 3.0 = 3.0

γγDor excitation mechanism temperature intervalDor excitation mechanism temperature interval

TTe

ffeff (

HD

494

34)

(H

D 4

9434

)

With LOSC, we can see if p and g modes can exist for this models With LOSC, we can see if p and g modes can exist for this models BUTBUT

We can not learn anything more from adiabatic pulsation modellingWe can not learn anything more from adiabatic pulsation modelling

Need non-adiabatic study to see if γDor/δSct oscillations can be Need non-adiabatic study to see if γDor/δSct oscillations can be excited for this modelsexcited for this models

MADMAD

Dupret & Grigahcène – private communicationDupret & Grigahcène – private communication

Guzik’s criterion ???Guzik’s criterion ???

Conclusions & Conclusions & ProspectsProspects

Challenging star to modeliseChallenging 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 studyNeed a non-adiabatic seismic study

Will be helped by a study of the Liège γDor models gridWill be helped by a study of the Liège γDor models grid

Constrain the blue edge of the γDor ISConstrain the blue edge of the γDor IS

Learn more about the γDor excitation mechanismLearn more about the γDor excitation mechanism

Learn more about γDor/δSct hybrid pulsatorsLearn more about γDor/δSct hybrid pulsators

Work in progress !Work in progress !

Thank you !Thank you !

LOSC LOSC adiabatic pulsation codeadiabatic pulsation code

Inputs :Inputs :

- choice of the grid step to compute oscillations- choice of the grid step to compute oscillations

- optimal distribution of points for p or g modes- optimal distribution of points for p or g modes

- scan- scan

- frequency spectrumfrequency spectrum

- equidistant scale in frequency (p modes) or in time equidistant scale in frequency (p modes) or in time

(g modes)(g modes)

- calculation of modes for an approximative frequency- calculation of modes for an approximative frequency

LOSC outputsLOSC outputs

- degree of the mode- degree of the mode

- order of the mode- order of the mode

- parity of the mode- parity of the mode

- (non-)dimensional frequency- (non-)dimensional frequency

- vertical energy fraction versus total energy- vertical energy fraction versus total energy

-Eigenfunctions of the modeEigenfunctions of the mode