Current open issues in probing interiors of solar-like oscillating main sequence stars
description
Transcript of Current open issues in probing interiors of solar-like oscillating main sequence stars
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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 T. Corbard, D. Reese, O. Creevey
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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
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A tout seigneur tout honneur, Noblesse oblige
The Sun
Solar constraints
• Luminosity, GM⊙, R, age, surface abundances (Z/X)s• Seismic constrainsFrom 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,)
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- 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-
Major challenges and open issues in the solar case
The Sun
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1993-2010: several revisions of the photospheric solar mixture2003: 3D model atmospheres + NLTE effects + improved atomic data➥ decrease of C, N, O, Ne, Ar and (Z/X)
GN93 GS98 AGS05 AGS09 Lod09 Caff10
Z/X 0.0245 0.0229 0.0165 0.0181 0.0191 0.0209
1- Initial abundances: the solar mixture
The Sun
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1993-2010: several revisions of the photospheric solar mixture2003: 3D model atmospheres + NLTE effects + improved atomic data➥ decrease of C, N, O, Ne, Ar and (Z/X)
Grevesse & Noels 93, Grevesse & Sauval 1998, Asplund et al. 05, Asplund & al 09, Lodders et al. 09, Caffau et al 10
GN93 GS98 AGS05 AGS09 Lod09 Caff10
Z/X 0.0245 0.0229 0.0165 0.0181 0.0191 0.0209
1- Initial abundances: the solar mixture
The Sun
2009-2010•Internal consistency of abundance determination from different ionisation levels of a given element •Consensus between independent determinations
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1 Initial abundances: the solar mixture
The Sun
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1 Initial abundances: the solar mixture
The Sun
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1 Initial abundances: the solar mixture
The Sun
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INPUT PHYSICS microscopic:Nuclear reactions opacities equation of state microscopic diffusion macroscopic: Convection rotation internal waves magnetic field et related transport
INPUT PARAMETERS mass initial composition evolutionary state
BOUNDARIES model atmospheres
NUMERICS
solar model
Mode physics
The sun
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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)
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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
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1 Abundances
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?
From the Sun to stars
1414Yveline Lebreton GAIA-ELSA Conf., Sèvres, France, 10 June 2010
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
reaction cross section:
2-Nuclear reaction rates The Sun
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recent significant progress in laboratory and theory➥ S-factor down to the Gamow peak
NOW and FUTURElow energy, high intensity underground
➦
2-Nuclear reaction rates The Sun
reaction cross section:
astrophysical factor (S-factor)
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Adelberger et al. 2010
high mass or/and advanced stages
low mass stars
CNO cycle
pp chain
2-Hydrogen burning reaction rates
CNO cycle
S(0) ➘ 50%
LUNA
experimental measurements
14N(p, γ)15O
The Sun
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CNO cycle efficiency is reduced
Sun: ECNO/ETOT= 0.8% vs.1.6% before
2- 14N(p,γ)15O burning reaction rate
From the Sun to analogue starsconvective core: smaller at given mass , appears at higher mass
LUNA, Formicola et al. 04
NACRE, Angulo et al. 01convective coresmaller at given mass appears at higher mass
1.2 M☉, Z=0.01
The Sun
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)2exp()(
)( E
ESE
reaction cross section
Electron screening
Seismic sun (Basu et al 1997)- model
AGS05
Model S
Model Sswitching
off e-
screening
Christensen-Dalsgaard, 2009
Salpeter 1954Shaviv, Shaviv1996; 2000
Controversy Bahcall et al 2000Weiss et al 2001
Dappen 2009
Exact impact of e- screening ?For the Sun and stars ?
2-Nuclear reaction rates The Sun
AGS09
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Adelberger et al. 2010
high mass or/and advanced stages
low mass stars
CNO cycle
pp chain
p(p, e+
ν)d
2-Hydrogen burning reaction rates
CNO cycle
The Sun
theoretical estimate onlybut helioseismic validation➦ rate constrained to ±15%
Weiss 2008pp+screening increase by 15% : AGS05 cs prior to 2003 standard solar modelsbelow th UCZ
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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 massMathias, Zahn, 1997 solar rotation profileTalon, Charbonnel 2003 Li dip
3- Rotationally induced transport The Sun
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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 massMathias, Zahn, 1997 solar rotation profileTalon, 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
3- Rotationally induced transport The Sun
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2
c
c
GN93 mixture
discrepancy for the sound speed below the UCZ increases
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The Sun3- Rotationally induced transport
Models from Marques 2010Lebreton 2010
AGS05• no rotation• rotation no surface J loss•rotation surface J loss
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From the Sun to stars: Talon, Zahn 1997, Eggenberger et al, Decressin et al 2009, Marques et al 2010
Validity of prescriptions, in particular Dh ?
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4-Internal wave induced transport
For profile, needs additional transport processes: waves mixing or BTalon, 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
The Sun
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 ?
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Include
- boundary: T- relation
- Inefficient turbulent convection - Mode physics : nonadiabatic effects thermal and dynamics
interaction radiation-pulsation interaction convection-pulsation
5-Near surface layers The Sun
Christensen-Dalsgaard , Perez Hernandez 1992 Christensen-Dalsgaard, Thompson 1997
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5-Model atmosphere and T- law
Blue solar observations GOLF (credit F. Baudin)Red solar model GN93, diffusion (Lebreton 2010)
The Sun
From the Sun to stars, SSM uses semi empirical models or Kurucz modelsEvolutionary models for stars usually use Eddington T-
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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 datareference frequency 0 = 3100 Hz fixed
Green fall on blue points
5-Correcting for near surface effects The Sun
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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 ?
5-Correcting for near surface effects The Sun
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5-Correcting for near surface effects
Inefficient superadiabatic turbulent convection: 3D simulationsPatched model versus non patched models:Frequencies closer to observed ones Rosenthal et al 1999, Li et al 2002
Samadi, Ludwig 2010
The Sun
Existence of a similar scaling for that contribution to near surface effects ?Then it could be investigated theoretically
5-Correcting for near surface effectsFrom the Sun to stars
Hotter stars, larger effects
Pturb/Ptot larger, ‘lift’ of the atmosphere higher larger difference between patched and non patched model frequenciessmaller gravity and/orhigher température, larger Pturb/Ptot
curves : a(obs/max)b
with adapted a,b Scaling not so easy …
Models from Samadi, Ludwig 2010
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5-Correcting for near surface effectsFrom the Sun to stars
… but possible
Care with the ‘patching’3D simu not perfect
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StarsFrom the Sun to solar-like oscillating MS stars:
Stars can differ from the Sun by : Mass, age , Metallicity, Y Convective core Rotation …. Add additional issues:
Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)
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StarsFrom the Sun to solar-like oscillating MS 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;
Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)
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StarsFrom the Sun to solar-like oscillating MS 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
Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)
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StarsFrom the Sun to solar-like oscillating MS 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
Here focus on low and intermediate mass MS up to ~ 1.5 Msol (F,G,K stars)
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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
Observational constraints:
3636
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
Observational constraints:
Deheuvels et al 2010
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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 regionsMonteiro et al 2000; Mazumdar, Antia 2001; Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..
d01
Observational constraints:
Deheuvels et al 2010
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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 regionsMonteiro et al 2000; Mazumdar, Antia 2001; Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..
Age, core properties, low degree modesHoudek, Gough 2007, 2008 ; Cunha, Metcalfe 2007; Cunha 2010
d01
Observational constraints:
Deheuvels et al 2010
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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 regionsMonteiro et al 2000; Mazumdar, Antia 2001; Mazumdar et al 2006; Roxburgh, Vorontsov 2003 ..
Age, core properties, low degree modesHoudek, 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
Observational constraints:
Deheuvels et al 2010
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Initial abundances: the chemical mixture
Stars
Barban et al 2009 ; Baudin 2010, Ballot et al 2010; Benomar et al 2009
unevolved and ‘massive’: convective core , radiative interior, thin convective outer layer , rotation
Different metallicity
Evolved: isothermal core
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LUNA, Formicola et al. 04
NACRE, Angulo et al. 01
CNO cycle efficiency is reduced
14N(p,γ)15O burning reaction rate
convective coresmaller at given mass appears at higher mass
1.2 M☉, Z=0.01
Stars
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Stars Gravitational settling and atomic diffusion:Ys decreases
Effect increases with massDiffusion too large for small envelope convective region ?
Fe/H~0.08 M ~1.42-1.50ov=0.-0.2
Fe/H~0 M ~1.36-1.37ov=0-0.2
Fe/H~-0.44M=1.1-1.15ov ~0-0.2
Fe/H~ -0.07
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Sun
Fe/H~0.09 M ~1.30
Fe/H~-0.11
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1.1-1.2 Msol metal poorCompact with thin convective envelope
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Mode degree identification
• (CoRoT) HD49933 Initial run 30 days2 scenarii : A : need for large core overshoot B : need for intermediate core overshoot Appourchaux et al 2008Initial run + long run 137 days + several independent data analyses scenario B is favored Benomar et al 2009
•(CoRoT) HD1814202 scenarii : A : need for large core overshoot B : need for intermediate core overshoot Barban et al 2009and others
Stars
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Mode identification:scaling relations
Bedding, Kjeldsen 2010 proposed to use scaling relations to help identifie the modes: scaled echelle diagram
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 B Garcia et al 2009
scales as <> ; scales as <>
Test on ‘twin stars’: Sun and 18 Sco - Ceti and Cen B
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HD203608 Mosser et al, 2008; Deheuvels et al 2010Low mass F8V ~6070K; ~0.95 Msol, Fe/H ~-0.5Scenario 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 AStars
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HD203608 Mosser et al, 2008; Deheuvels et al 2010Low mass F8V ~6070K; ~0.95 Msol, Fe/H ~-0.5Scenario 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 A
Scenario B Scenario B
clearly confirms scenario A (Deheuvels, 2010, PhD)
Stars
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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?
Stars
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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?
Stars
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
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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?
Stars
l=2 large error bars unreliable
AGS05: difficult to find a model satisfying all the constrains when Z/X is on the smaller part of the authorized interval
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
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HD49933Stars
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
•Diffusion and helium surface abundance
/<> versus /<>Scaling: oscillation phase independent of age
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HD49933: convective coreStars
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 overshootbut _ov cannot be zero
Diffusion : mild overshoot _ov=0.21Hp
•Diffusion
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HD49933: convective coreStars
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
•Diffusion and rotationally induced transportInitial angular rotation set to fit P=3.4 days at the age of HD49933
Models computed by J. Marques
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Echelle diagrams for HD49933Blue observationsRed model
86 HZ for both 86.5 HZ for model
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HD181420
Scenario 1 favors for intermediate core overshoot
Stars
( 6580K ; [Fe/H] ~0 or -0.12)
two models: 1.36 M with 0.2 Hp overshoot 1.37 M without overshootNo 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
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l=0 l=1l=2
10km/s
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rotationa ‘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 ⊙ !
HD181420Stars
5656
Effect of the non-spherically part of centrifugal distortion
on échelle diagram and asymetries of splitting multiplets (WarM oscillation code)
l=0 l=1l=2
10km/s
25 km/s
Asymetries of the splitting clearly appear in échelle diagram already at 10 km/sContribute to surface effects 27
rotationa ‘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 ⊙ !
HD181420Stars
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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 of rapid rotation ; differential in latitude Ratio vspot/nurot gives a constraint on spot model
Effect of rotation is included only through effect of nonspherical centrifugal distorsion on the frequencies
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
d01 indicates no oveshoot if vrot=20-25km/sor 0.2 Hp overshoot and vrot = 2 - 15 km/s
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• 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
• Case of HD 49385 : detection of an l=1 avoided crossing based on the distortion of the ridge.
HD49385: mixed mode and mixtureStars
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EZ
GN93 no overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
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EZ
GN93 no overshooting
GN93 overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
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EZ
GN93 no overshooting
GN93 overshooting
ASP05 no overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
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Kepler data and scaling relations
Some degeneracy in determining mass and age or radiusdue to the chemical composition
Which accuracy in non seismic determination of Y,Z is needed ?
Corot targets, ground based observations4 Kepler targets provided by O. Creevey with permission of KASK group
Stars
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Conclusion
Et tout le reste…..
For exemple
Semi convection versus mixing for low mass starsStellar activityB
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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?
Stars
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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?
Stars
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
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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?
Stars
l=2 large error bars unreliable
AGS05: Difficult to find a model satisfying all the constrains when Z/X is on the smaller part of the authorized interval
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
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HD49933Stars
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
•Diffusion and helium surface abundance
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HD49933: convective coreStars
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 overshootbut _ov cannot be zero
Diffusion : mild overshoot _ov=0.21Hp
•Diffusion
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HD49933: convective coreStars
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
•Diffusion and rotationally induced transportInitial angular rotation set to fit P=3.4 days at the age of HD49933
Models computed by J. Marques
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HD181420
Scenario 1 favors for intermediate core overshoot
Stars
( 6580K ; [Fe/H] ~0 or -0.12)
two models: 1.36 M with 0.2 Hp overshoot 1.37 M without overshootNo 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
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Effect of the non-spherically part of centrifugal distortion
on échelle diagram and asymetries of splitting multiplets (WarM oscillation code)
l=0 l=1l=2
10km/s
25 km/s
Asymetries of the splitting clearly appear in échelle diagram already at 10 km/sContribute to surface effects 27
rotationa ‘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 ⊙ !
HD181420Stars
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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 of rapid rotation ; differential in latitude Ratio vspot/nurot gives a constraint on spot model
Effect of rotation is included only through effect of nonspherical centrifugal distorsion on the frequencies
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
d01 indicates no oveshoot if vrot=20-25km/sor 0.2 Hp overshoot and vrot = 2 - 15 km/s
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• 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
• Case of HD 49385 : detection of an l=1 avoided crossing based on the distortion of the ridge.
HD49385: mixed mode and mixtureStars
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EZ
GN93 no overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
78
EZ
GN93 no overshooting
GN93 overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
79
EZ
GN93 no overshooting
GN93 overshooting
ASP05 no overshooting
Models fitting all surface parameters + + frequency of the avoided croissing
We fit the distortion of the ridge(Deheuvels et al. 2010 in prep.)
Stars
80
Kepler data and scaling relations
Some degeneracy in determining mass and age or radiusdue to the chemical composition
Which accuracy in non seismic determination of Y,Z is needed ?
Corot targets, ground based observations4 Kepler targets provided by O. Creevey with permission of KASK group
Stars
81
Conclusion
Et tout le reste…..
For exemple
Semi convection versus mixing for low mass starsStellar activityB l=2, l=3 modesMode physics….
82