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Current open issues in probing interiors of solar-like oscillating main sequence stars. MJ Goupil, Y. Lebreton Paris Observatory. J.P. Marques, R. Samadi , S. Talon ,J.Provost, S. Deheuvels , K. Belkacem, O. Benomar, F. Baudin, J. Ballot, B.Mosser

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slide1

Current open issues in probing

interiors of solar-like oscillating main sequence stars

MJ Goupil, Y. Lebreton

Paris Observatory

J.P. Marques, R. Samadi, S. Talon ,J.Provost, S. Deheuvels,

K. Belkacem, O. Benomar, F. Baudin, J. Ballot, B.Mosser

T. Corbard, D. Reese, O. Creevey

slide2

Outline

I The Sun

Major open issues

From the Sun to stars

II Solar like oscillating MS stars

Open issues illustrated with

CoRoT stars: HD49933, HD181420, HD42385

ground based observed HD208

Kepler data

Reviews: Basu, Antia 2008, Christensen-Dalsgaard, 2009; Turck Chieze et al , 2010

slide3

A tout seigneur tout honneur, Noblesse oblige

The Sun

  • Solar constraints
  • Luminosity, GM⊙, R, age, surface abundances (Z/X)s
  • Seismic constrains
  • From inversion of a large set of mode frequencies
  • Found to be enough independent of the reference model
  • -base of the upper convective zone rbzc
  • -surface helium abundance Ys
  • -ionization regions through 1
  • -sound speed profile : seismic solar model c(r )
  • -rotation profile (r,)
slide4

The Sun

Major challenges and open issues in the solar case

  • - Input parameters: surface abundances ?
  • Interior : sound speed : origin of the discrepancy below the
  • convection zone
  • Rotation profile
  • Near surface layers
  • Probing the core
  • Mode physics : line widths and amplitudes
  • convection-pulsation interaction

-

slide5

1- Initial abundances: the solar mixture

The Sun

1993-2010: several revisions of the photospheric solar mixture

2003: 3D model atmospheres + NLTE effects + improved atomic data

➥ decrease of C, N, O, Ne, Ar and (Z/X)

slide6

1- Initial abundances: the solar mixture

The Sun

1993-2010: several revisions of the photospheric solar mixture

2003: 3D model atmospheres + NLTE effects + improved atomic data

➥ decrease of C, N, O, Ne, Ar and (Z/X)

  • 2009-2010
  • Internal consistency of abundance determination
  • from different ionisation levels of a given element
  • Consensus between independent determinations

Grevesse & Noels 93, Grevesse & Sauval 1998, Asplund et al. 05, Asplund & al 09, Lodders et al. 09, Caffau et al 10

6

slide10

NUMERICS

BOUNDARIES

model atmospheres

INPUT PARAMETERS

mass

initial composition

evolutionary state

INPUT PHYSICS

microscopic:

Nuclear reactions

opacities

equation of state

microscopic diffusion

macroscopic:

Convection 

rotation

internal waves

magnetic field

et

related transport

solar model

The sun

Mode physics

slide11

1- Opacities: mixture and choice of tables

The Sun

Z/X decrease : major impact in solar models  radiative opacities

Major differences just below the convection zone (Oxygen, Neon)

slide12

1- Opacities: mixture and choice of tables

The Sun

Z/X decrease : major impact in solar models  radiative opacities

Major differences just below the convection zone (Oxygen, Neon)

Check opacities: uncertainties assessed with OPAL/OP

Opacity comparison for a 1 Msun calibrated solar model

Difference in opacity dominated by the difference in the mixture (but less if AGS09 replaces AGS05).

OP opacities give a better fit than OPAL. However in that region, there is no way to change the OP opacity by a sufficient amount to compensate the effects of mixture (Badnell et al. 2005)

cf S. Basu ‘s talk S. Turck-Chieze ‘s talk

12

slide13

1 Abundances

From the Sun to stars

Abundances of other stars determined by reference to the Sun, hence all stars affected

can other stars be discriminating ?

Impact of some mismatch between 3D atmosphere models (solar abundances) and 1D models (stellar abundances)?

Z/X could be affected

Impact of inconsistency when modelling other stars with AGS mixtures if their [Fe/H] not determined from 3D models?

Bailey et al. 07, Moses et al. 09

slide14

reaction cross section:

2-Nuclear reaction rates

The Sun

  • in stars:reactions occur at low energy: few keV to 0.1 MeV
  • rates from:
    • experimental data but to be extrapolated to low E
    • theory

Yveline Lebreton

GAIA-ELSA Conf., Sèvres, France, 10 June 2010

14

slide15

NOW and FUTURE

low energy, high intensity underground

reaction cross section:

2-Nuclear reaction rates

astrophysical factor (S-factor)

The Sun

recent significant progress in laboratory and theory

➥ S-factor down to the Gamow peak

slide16

LUNA

2-Hydrogen burning reaction rates

CNO cycle

high mass

or/and advanced stages

experimental measurements

14N(p, γ)15O

S(0) ➘ 50%

pp chain

low mass stars

The Sun

CNO cycle

Adelberger et al. 2010

16

slide17

NACRE, Angulo et al. 01

LUNA, Formicola et al. 04

The Sun

2- 14N(p,γ)15O burning reaction rate

CNO cycle efficiency is reduced

Sun: ECNO/ETOT=0.8% vs.1.6% before

From the Sun to analogue stars

convective core: smaller at given mass , appears at higher mass

convective core

smaller at given mass

appears at higher mass

1.2 M☉, Z=0.01

slide18

2-Nuclear reaction rates

The Sun

reaction cross section

Seismic sun (Basu et al 1997)- model

Electronscreening

AGS09

AGS05

Salpeter 1954

Shaviv, Shaviv1996; 2000

ControversyBahcall et al 2000

Weiss et al 2001

Dappen 2009

Exact impact of e- screening ?

For the Sun and stars ?

Model S

switching off

e- screening

Model S

Christensen-Dalsgaard, 2009

slide19

2-Hydrogen burning reaction rates

CNO cycle

high mass

or/and advanced stages

pp chain

low mass stars

p(p, e+ ν)d

The Sun

theoretical estimate only

but helioseismic validation

➦ rate constrained to ±15%

CNO cycle

Adelberger et al. 2010

Weiss 2008

pp+screening increase by 15% :

AGS05 cs  prior to 2003 standard solar models

below th UCZ

slide20

The Sun

3- Rotationally induced transport

Open issues: flat rotation profile in the radiative region

discrepancy for the sound speed below the UCZ

Most recent, based on a model of diffusion-advection transport (Zahn 1992, Maeder, Zahn 1998, Chaboyer, Zahn, 1992, Mathis, Zahn 2004)

Talon, Zahn 1997, high mass

Mathias, Zahn, 1997 solar rotation profile

Talon, Charbonnel 2003 Li dip

slide21

The Sun

3- Rotationally induced transport

  • Open issues: flat rotation profile in the radiative region
  • discrepancy for the sound speed below the UCZ
  • Most recent, based on a model of diffusion-advection transport (Zahn 1992, Maeder, Zahn 1998, Chaboyer, Zahn, 1992, Mathis, Zahn 2004)
  • Talon, Zahn 1997, high mass
  • Mathias, Zahn, 1997 solar rotation profile
  • Talon, Charbonnel 2003 Li dip
  • Palacios et al 2006;
  • Turck-Chieze et al 2010 :
  • Initial velocity (slow or ‘fast’ sun)
  • matters
  • slow: microscopic diffusion dominates
  • Initially rapid enough: meridional
  • circulation dominates over turbulent shear

GN93 mixture

discrepancy for the sound speed below the UCZ increases

21

slide22

The Sun

3- Rotationally induced transport

  • AGS05
  • no rotation
  • rotation no surface J loss
  • rotation surface J loss

Validity of prescriptions,

in particular Dh ?

Models from Marques 2010

Lebreton 2010

From the Sun to stars: Talon, Zahn 1997, Eggenberger et al, Decressin et al 2009, Marques et al 2010

22

22

slide23

The Sun

4-Internal wave induced transport

For  profile, needs additional transport processes: waves mixing or B

Talon, Charbonnel 2005 internal waves

⊙ flat profil

Li dip on the cool side

B is also able to ⊙ flat profil Eggenberger et al 2005, Yang, Bi 2007

Open issue: either one ? or both ?

depends on various precriptions and assumptions

Sound speed

Evolution of sound speed profil with age Talon 2010 with 2005 models

(Talon, Charbonnel 2005) but not calibrated models yet

For cs, needs higher opacities or higher helium below UZC ie higher He gradient

Any mixing below UZC which smoothes the gradient goes in the wrong direction ? Then advection process? Waves ?

23

slide24

The Sun

5-Near surface layers

Include

- boundary: T- relation

- Inefficient turbulent convection

- Mode physics : nonadiabatic effects

thermal and dynamics

interaction radiation-pulsationinteraction convection-pulsation

Christensen-Dalsgaard , Perez Hernandez 1992

Christensen-Dalsgaard, Thompson 1997

slide25

The Sun

5-Model atmosphere and T- law

Blue solar observations GOLF (credit F. Baudin)

Red solar model GN93, diffusion (Lebreton 2010)

From the Sun to stars, SSMuses semi empirical models or Kurucz models

Evolutionary models for stars usually use Eddington T-

slide26

The Sun

5-Correcting for near surface effects

Kjeldsen et al 2008 proposed a mean to correct for near surface effects

Green :  corrected with

a(obs/0)b

a,b fitted from the data

reference frequency

0= 3100 Hz fixed

Green fall on blue points

slide27

5-Correcting for near surface effects

The Sun

Of course valid only over the fitted domain,perhaps enough for stars

How much parameters a,b, 0 do depend on the adopted model ?

Validity for other stars ?

slide28

The Sun

5-Correcting for near surface effects

Inefficient superadiabatic turbulent convection: 3D simulations

Patched model versus non patched models:

Frequencies closer to observed ones

Rosenthal et al 1999, Li et al 2002

Samadi, Ludwig 2010

Existence of a similar scaling for that

contribution to near surface effects ?

Then it could be investigated theoretically

slide29

From the Sun

to stars

5-Correcting for near surface effects

Hotter stars, larger effects

Pturb/Ptot larger, ‘lift’ of the

atmosphere higher

larger difference between

patched and non patched

model frequencies

smaller gravity and/or

higher température,

larger Pturb/Ptot

curves : a(obs/max)b

with adapted a,b

Scaling not so easy …

Models from Samadi, Ludwig 2010

slide30

From the Sun

to stars

5-Correcting for near surface effects

… but possible

Care with the ‘patching’

3D simu not perfect

slide31

Stars

From the Sun to solar-like oscillating MS stars:

Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)

Stars can differ from the Sun by :

Mass, age , Metallicity, Y

Convective core

Rotation

….

 Add additional issues:

slide32

Stars

From the Sun to solar-like oscillating MS stars:

Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)

  • Stars can differ from the Sun by :
  • Mass, age , Metallicity, Y
  • Convective core
  • Rotation
  • ….
  •  Add additional issues:
  • Determining input parameters: mass, age, chemical composition Y0, (Z/X)0, , ov,
  • usually through location in HR diagram and spectroscopic information
  • as accurate as possible L, Teff, Z/X, R…
  • but M, R, age , surface chemical composition not well known;

32

32

slide33

Stars

From the Sun to solar-like oscillating MS stars:

Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)

  • Stars can differ from the Sun by :
  • Mass, age , Metallicity, Y
  • Convective core
  • Rotation
  • ….
  •  Add additional issues:
  • input parameters are needed: mass, age, chemical composition Y0, (Z/X)0, , ov,
  • Most often M, R, age , surface chemical composition not well known;
  • usually through location in HR diagram and spectroscopic information
  • These incertainties family of models rather than a unique one
  • and input physics dependent
  •  desentangling degeneracy of these effects on seismic diagnostics

33

slide34

Stars

From the Sun to solar-like oscillating MS stars:

Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)

  • Stars can differ from the Sun by :
  • Mass, age , Metallicity, Y
  • Convective core
  • Rotation
  • ….
  •  Add additional issues:
  • input parameters are needed: mass, age, chemical composition Y0, (Z/X)0, , ov,
  • Most often M, R, age , surface chemical composition not well known;
  • usually through location in HR diagram and spectroscopic information
  • These incertainties family of models rather than a unique one
  • and input physics dependent
  •  desentangling degeneracy of these effects on seismic diagnostics
  • For a given star, seismic observations can lead to 2 scenarii for mode degree
  • identifications

34

34

slide35

Observational constraints:

Stars

  • Additional seismic diagnostics and efforts in obtaining seismic constraints
  • independent of models
  • Mean large separation: Mosser Appourchaux, 2009, Roxburgh 2009, Mathur et al 2010
slide36

Observational constraints:

Stars

  • Additional seismic diagnostics and efforts in obtaining seismic constraints
  • independent of models
  • Mean large separation: Mosser Appourchaux, 2009, Roxburgh 2009, Mathur et al 2010
  • Sensitivity to convective core properties: period related to acoustic radius of core convective radius:Provost et al, 1993 Mazumdar, Antia 2001; Miglio et al 2005,
  • Roxburgh, Vorontsov 2007…

d01

Deheuvels et al 2010

36

slide37

Observational constraints:

Stars

  • Additional seismic diagnostics and efforts in obtaining seismic constraints
  • independent of models
  • Mean large separation: Mosser Appourchaux, 2009, Roxburgh 2009, Mathur et al 2010
  • Sensitivity to convective core properties: period related to acoustic radius of core convective radius:Provost et al, 1993 Mazumdar, Antia 2001; Miglio et al 2005,
  • Roxburgh, Vorontsov 2001, 2005, Roxburgh 2005
  • Base of the UCZ, Ionization regions
  • Monteiro et al 2000; Mazumdar, Antia 2001;
  • Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..

d01

Deheuvels et al 2010

37

37

slide38

Observational constraints:

Stars

  • Additional seismic diagnostics and efforts in obtaining seismic constraints
  • independent of models
  • Mean large separation: Mosser Appourchaux, 2009, Roxburgh 2009, Mathur et al 2010
  • Sensitivity to convective core properties: period related to acoustic radius of core convective radius:Provost et al, 1993 Mazumdar, Antia 2001; Miglio et al 2005,
  • Roxburgh, Vorontsov 2007…
  • Base of the UCZ, Ionization regions
  • Monteiro et al 2000; Mazumdar, Antia 2001;
  • Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..
  • Age, core properties, low degree modes
  • Houdek, Gough 2007, 2008 ; Cunha, Metcalfe 2007;
  • Cunha 2010

d01

Deheuvels et al 2010

38

38

38

slide39

Observational constraints:

Stars

  • Additional seismic diagnostics and efforts in obtaining seismic constraints
  • independent of models
  • Mean large separation: Mosser Appourchaux, 2009, Roxburgh 2009, Mathur et al 2010
  • Sensitivity to convective core properties: period related to acoustic radius of core convective radius:Provost et al, 1993 Mazumdar, Antia 2001; Miglio et al 2005,
  • Roxburgh, Vorontsov 2007…
  • Base of the UCZ, Ionization regions
  • Monteiro et al 2000; Mazumdar, Antia 2001;
  • Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..
  • Age, core properties, low degree modes
  • Houdek, Gough 2007, 2008 ; Cunha, Metcalfe 2007;
  • Cunha 2010
  • Enough observed stars enable to validate systematic properties: scalings relations
  • Bedding, Kjeldsen 2010, Kjeldsen et al 2008

d01

Deheuvels et al 2010

39

slide40

Initial abundances: the chemical mixture

Stars

Evolved: isothermal core

unevolved and ‘massive’:

convective core ,

radiative interior,

thin convective outer layer ,

rotation

Different metallicity

Barban et al 2009 ; Baudin 2010, Ballot et al 2010; Benomar et al 2009

slide41

NACRE, Angulo et al. 01

LUNA, Formicola et al. 04

Stars

14N(p,γ)15O burning reaction rate

CNO cycle efficiency is reduced

convective core

smaller at given mass

appears at higher mass

1.2 M☉, Z=0.01

slide42

Stars

Gravitational settling and atomic diffusion:

Ys decreases

Effect increases with mass

Diffusion too large for small envelope convective region ?

Fe/H~0.08

M ~1.42-1.50

ov=0.-0.2

Fe/H~0.09

M ~1.30

Fe/H~0

M ~1.36-1.37

ov=0-0.2

Fe/H~-0.11

Fe/H~-0.44

M=1.1-1.15

ov ~0-0.2

1.1-1.2 Msolmetalpoor

Compact withthin convective envelope

Sun

Fe/H~ -0.07

42

6

slide43

Stars

Mode degree identification

  • (CoRoT) HD49933 Initial run 30 days
  • 2 scenarii : A : need for large core overshoot
  • B : need for intermediate core overshoot
  • Appourchaux et al 2008
  • Initial run + long run 137 days + several independent data analyses scenario B is favored Benomar et al 2009
  • (CoRoT) HD181420
  • 2 scenarii : A : need for large core overshoot
  • B : need for intermediate core overshoot
  • Barban et al 2009
  • and others
slide44

Mode identification:scaling relations

Bedding, Kjeldsen 2010 proposed to use scaling relations to help

identifie the modes: scaled echelle diagram

  • scales as <> ;  scales as <>

Test on ‘twin stars’: Sun and 18 Sco -  Ceti and  Cen B

  • Reference star (CoRoT) HD49933 scenario B LR+IR ( Benomar et al 2009
  • (CoRoT) HD181420 scenario 1 Barban et al 2009, Gaulme et al 2009, Mosser 2010
  • (CoRoT) HD181906 scenario BGarcia et al 2009
slide45

Stars

Scenario A

HD203608Mosser et al, 2008; Deheuvels et al 2010

Low mass F8V ~6070K; ~0.95 Msol, Fe/H ~-0.5

Scenario A: clear evidence that

definetly requires mild overshoot and

survical of convective core despite its small mass, old age but due low metallicity

Ground based observations: 2 scenarii: arguments to choose scenario A

but some check welcome

45

slide46

Stars

Scenario A

HD203608Mosser et al, 2008; Deheuvels et al 2010

Low mass F8V ~6070K; ~0.95 Msol, Fe/H ~-0.5

Scenario A: clear evidence that

definetly requires mild overshoot and

survical of convective core despite its small mass, old age but due low metallicity

Ground based observations: 2 scenarii: arguments to choose scenario A

but some check welcome

Scenario B

Scenario B

clearly confirms scenario A (Deheuvels, 2010, PhD)

46

46

slide47

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

slide48

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

l=2 large error bars unreliable

  • Calibration: large separation  and small spacing d01
  • large separation 
  • Mean value <> : given M, Z/X, Y, physics /  : fix the age
  • Period of oscillation: acoustic depth of He++ ionisation
  • phase of oscillation: sensitive to _cgm to Y
  • quite constraining together with non seismic constraints
  • small spacing d01 sensitive to core conditions
  • period = acoustic radius of convective core boundary

48

slide49

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

l=2 large error bars unreliable

  • Calibration: large separation  and small spacing d01
  • large separation 
  • Mean value <> : given M, Z/X, Y, physics /  : fix the age
  • Period of oscillation: acoustic depth of He++ ionisation
  • phase of oscillation: sensitive to _cgm to Y
  • quite constraining together with non seismic constraints
  • small spacing d01 sensitive to core conditions
  • period = acoustic radius of convective core boundary

AGS05: difficult to find a model satisfying all the constrains

when Z/X is on the smaller part of the authorized interval

49

slide50

Stars

HD49933

  • Diffusion and helium surface abundance

Effects of its low metallicity:

AGS05 no diffusion 

AGS05 diffusion needs to start

with large Yini

needs to include Dturb

still small Ys value, (Z/X) Ys=0.10

Less extreme AGS09: Ys=0.18

/<>

versus /<>

oscillation phase independent of age

Scaling:

50

slide51

Stars

HD49933: convective core

  • Diffusion

Effects of its low metallicity:

GN93: convective core, sensitivity

to core overshoot; need for

intermediate

to large core overshoot

_ov = 0.25-0.3Hp

AGS05: small convective core ,

weak sensitivity to core overshoot

but _ov cannot be zero

Diffusion : mild overshoot _ov=0.21Hp

slide52

Stars

HD49933: convective core

  • Diffusion and rotationally induced transport
  • Initial angular rotation set to fit P=3.4 days at the age of HD49933

AGS05

no diffusion ov=0.2 Hp: does not fit

Diffusion, ov=0.2 : fits

Diffusion+rotation ov=0.2 : fits

Diffusion+rotation no ov : does

not fit

But requires proper calibration

52

Models computed by J. Marques

slide53

Echelle diagrams for HD49933

Blue observations

Red model

86.5 HZ for model

86 HZ for both

slide54

Stars

HD181420

( 6580K ; [Fe/H] ~0 or -0.12)‏

Scenario 1 favors for intermediate core overshoot

two models: 1.36 M with 0.2 Hp overshoot

1.37 M without overshoot

No diffusion- No rotation

Secondary oscillation component in the large separation not reproduced by models.

Its ‘period’ corresponds to the base of the convective zone

but is it real ?

Provost 2010, Goupil et al 2009,

Michel, Mazumdar 2010, Mosser 2010

Data from Barban et al; Gaulme et al, Benomar et al

slide55

Stars

HD181420

rotation

a ‘rapid’ rotator compared to the Sun

With R=1.66 R and split = (3.±1 ) Hz

Rotational velocity v = 21.9 ± 7.3 km/s

=2/(GM/R3) = 320 ⊙!

l=0

l=1

l=2

10km/s

27

slide56

Stars

HD181420

rotation

a ‘rapid’ rotator compared to the Sun

With R=1.66 R and split = (3.±1 ) Hz

Rotational velocity v = 21.9 ± 7.3 km/s

=2/(GM/R3) = 320 ⊙!

Effect of the non-spherically part of centrifugal distortion

on échelle diagram and asymetries of splitting multiplets

(WarM oscillation code)

l=0

l=1

l=2

10km/s

25 km/s

Asymetries of the splitting clearly appear in échelle diagram already at 10 km/s

Contribute to surface effects

56

27

slide57

1.36 model with overshoot:

Rotation (vrot=2, 15, 20, 25, 30 km/s)‏

included in computing the eigenfrequencies*

decreases the mean value of d01.

The higher v, the lower d01

Effect of rotation is included only through effect of nonspherical centrifugal distorsion on the frequencies

d01 indicates

no oveshoot if vrot=20-25km/s

or

0.2 Hp overshoot and vrot = 2 - 15 km/s

rot = (4.5 ± 0.5) Hz (v sin i + R)

spot = (5.144 ± 0.068) Hz (Fourier)

split = (2.6 ± 0.4) Hz (scenario 1) (sismo)

indication ofrapid rotation ; differential in latitude

Ratio vspot/nurot gives a constraint on spot model

25

slide58
Coupling between the p-mode cavity and the g-mode cavity

=> low-degree avoided crossings are associated with a characteristic distortion of the ridge in the échelle diagram (Deheuvels & Michel 2009)

weak coupling

strong coupling

Stars

HD49385: mixed mode and mixture

  • Case of HD 49385 : detection of an l=1 avoided crossing based on the distortion of the ridge.
slide59

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

slide60

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

GN93 overshooting

slide61

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

GN93 overshooting

ASP05 no overshooting

slide62

Stars

Kepler data and scaling relations

Corot targets, ground based observations

4 Kepler targets provided by O. Creevey with permission of KASK group

Some degeneracy in determining mass and age or radius

due to the chemical composition

Which accuracy in non seismic determination of Y,Z is needed ?

slide63

Conclusion

Et tout le reste…..

For exemple

Semi convection versus mixing for low mass stars

Stellar activity

B

slide67

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

slide68

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

l=2 large error bars unreliable

  • Calibration: large separation  and small spacing d01
  • large separation 
  • Mean value <> : given M, Z/X, Y, physics /  : fix the age
  • Period of oscillation: acoustic depth of He++ ionisation
  • phase of oscillation: sensitive to _cgm to Y
  • quite constraining together with non seismic constraints
  • small spacing d01 sensitive to core conditions
  • period = acoustic radius of convective core boundary

68

slide69

Stars

HD49933: a low metallicity low mass star

Initial run + long run 137 days - Scenario B [Fe/H]=-0.4 +/- 0.1

How well current models can reproduce the observations?

Can we find families of models satisfying all the obs. constraints?

l=2 large error bars unreliable

  • Calibration: large separation  and small spacing d01
  • large separation 
  • Mean value <> : given M, Z/X, Y, physics /  : fix the age
  • Period of oscillation: acoustic depth of He++ ionisation
  • phase of oscillation: sensitive to _cgm to Y
  • quite constraining together with non seismic constraints
  • small spacing d01 sensitive to core conditions
  • period = acoustic radius of convective core boundary

AGS05: Difficult to find a model satisfying all the constrains

when Z/X is on the smaller part of the authorized interval

69

slide70

Stars

HD49933

  • Diffusion and helium surface abundance

Effects of its low metallicity:

AGS05 no diffusion 

AGS05 diffusion needs to start

with large Yini

needs to include Dturb

still small Ys value, (Z/X) Ys=0.10

Less extreme AGS09: Ys=0.18

70

slide71

Stars

HD49933: convective core

  • Diffusion

Effects of its low metallicity:

GN93: convective core, sensitivity

to core overshoot; need for

intermediate

to large core overshoot

_ov = 0.25-0.3Hp

AGS05: small convective core ,

weak sensitivity to core overshoot

but _ov cannot be zero

Diffusion : mild overshoot _ov=0.21Hp

slide72

Stars

HD49933: convective core

  • Diffusion and rotationally induced transport
  • Initial angular rotation set to fit P=3.4 days at the age of HD49933

AGS05

no diffusion ov=0.2 Hp: does not fit

Diffusion, ov=0.2 : fits

Diffusion+rotation ov=0.2 : fits

Diffusion+rotation no ov : does

not fit

But requires proper calibration

72

Models computed by J. Marques

slide73

Stars

HD181420

( 6580K ; [Fe/H] ~0 or -0.12)‏

Scenario 1 favors for intermediate core overshoot

two models: 1.36 M with 0.2 Hp overshoot

1.37 M without overshoot

No diffusion- No rotation

Secondary oscillation component in the large separation not reproduced by models.

Its ‘period’ corresponds to the base of the convective zone

but is it real ?

Provost 2010, Goupil et al 2009,

Michel, Mazumdar 2010, Mosser 2010

Data from Barban et al; Gaulme et al, Benomar et al

slide74

Stars

HD181420

rotation

a ‘rapid’ rotator compared to the Sun

With R=1.66 R and split = (3.±1 ) Hz

Rotational velocity v = 21.9 ± 7.3 km/s

=2/(GM/R3) = 320 ⊙!

Effect of the non-spherically part of centrifugal distortion

on échelle diagram and asymetries of splitting multiplets

(WarM oscillation code)

l=0

l=1

l=2

10km/s

25 km/s

Asymetries of the splitting clearly appear in échelle diagram already at 10 km/s

Contribute to surface effects

27

slide75

1.36 model with overshoot:

Rotation (vrot=2, 15, 20, 25, 30 km/s)‏

included in computing the eigenfrequencies*

decreases the mean value of d01.

The higher v, the lower d01

Effect of rotation is included only through effect of nonspherical centrifugal distorsion on the frequencies

d01 indicates

no oveshoot if vrot=20-25km/s

or

0.2 Hp overshoot and vrot = 2 - 15 km/s

rot = (4.5 ± 0.5) Hz (v sin i + R)

spot = (5.144 ± 0.068) Hz (Fourier)

split = (2.6 ± 0.4) Hz (scenario 1) (sismo)

indication ofrapid rotation ; differential in latitude

Ratio vspot/nurot gives a constraint on spot model

25

slide76
Coupling between the p-mode cavity and the g-mode cavity

=> low-degree avoided crossings are associated with a characteristic distortion of the ridge in the échelle diagram (Deheuvels & Michel 2009)

weak coupling

strong coupling

Stars

HD49385: mixed mode and mixture

  • Case of HD 49385 : detection of an l=1 avoided crossing based on the distortion of the ridge.
slide77

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

slide78

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

GN93 overshooting

slide79

Models fitting all surface parameters +  + frequency of the avoided croissing

We fit the distortion of the ridge

(Deheuvels et al. 2010 in prep.)

Stars

EZ

GN93 no overshooting

GN93 overshooting

ASP05 no overshooting

slide80

Stars

Kepler data and scaling relations

Corot targets, ground based observations

4 Kepler targets provided by O. Creevey with permission of KASK group

Some degeneracy in determining mass and age or radius

due to the chemical composition

Which accuracy in non seismic determination of Y,Z is needed ?

slide81

Conclusion

Et tout le reste…..

For exemple

Semi convection versus mixing for low mass stars

Stellar activity

B

l=2, l=3 modes

Mode physics

….

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