Current open issues in probing interiors of solar-like oscillating main sequence stars

1. 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

2. 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

3. 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,)

4. 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 -

5. 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)

6. 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

7. 1 Initial abundances: the solar mixture The Sun

8. 1 Initial abundances: the solar mixture The Sun

9. 1 Initial abundances: the solar mixture The Sun

10. 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

11. 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)

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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-

26. 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

27. 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 ?

28. 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

29. 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

30. From the Sun to stars 5-Correcting for near surface effects … but possible Care with the ‘patching’ 3D simu not perfect

31. 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:

32. 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

33. 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

34. 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

35. 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

36. 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

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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?

48. 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

49. 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

50. 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