1 / 23

Limits on Solar CNO From Helioseismology @Special Session 13 IAU - XXVIII GA Aldo Serenelli

Limits on Solar CNO From Helioseismology @Special Session 13 IAU - XXVIII GA Aldo Serenelli Institute of Space Sciences (CSIC-IEEC) Bellaterra, Spain. Outline. High and low solar metallicity: why metals matter

ronat
Download Presentation

Limits on Solar CNO From Helioseismology @Special Session 13 IAU - XXVIII GA Aldo Serenelli

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Limits on Solar CNO From Helioseismology @Special Session 13 IAU - XXVIII GA Aldo Serenelli Institute of Space Sciences (CSIC-IEEC) Bellaterra, Spain SpS 13 - IAUGA

  2. Outline • High and low solar metallicity: why metals matter • Helioseismic probes of solar structure: impact of metallicity differences – degeneracy with opacity • Deriving abundances from helioseismology • Opacities • Opacity independent probes of solar metallicity SpS 13 - IAUGA

  3. Solar Abundances Solar abundances • Differences • New 3-D hydrodynamic models of solar atmosphere • NLTE treatment of some elements • Refined selection of lines (e.g. identification of blends) Two paradigmatic sets Reduction of CNO(Ne) ~ 30-40% GS98 or GN93 representative of high-Z comp. AGSS09 or AGS05 representative of low-Z comp. log EX= log (NX/NH)+12 GS98: Grevesse & Sauval (1998) AGSS09: Asplund et al. (2009) SpS 13 - IAUGA

  4. Metals Matter in Solar Interior • Large contribution to rad. opacity k (between 30 to 80%) • O most important individual contribution • Radiative temperature gradient •  temperature stratification in radiative interior • Contribution (minor) to EOS • Changes in nuclear rates, particularly CNO rates SpS 13 - IAUGA

  5. Metals & Opacity Effect of individual elements on radiative opacity Heavy (eg. Fe, Si) : solar core  helium Intermediate (Ne, O): radiat. envelope  RCZ Light (C, N): convective envelope Helioseismology largely insensitive to C & N SpS 13 - IAUGA

  6. Helioseismic Probes Acoustic modes --- structural quantities: p, r, G1, c2 can be obtained “directly” Modes characterized by (n,l,m) Different modes sample the solar interior differently Inner turning-point radius determined by SpS 13 - IAUGA

  7. Helioseismic Probes Inversions: take two independent variables from the pool (p, r, c2, G1) e.g. c2, r or c2, G1 and construct radial profiles SpS 13 - IAUGA

  8. Sound and Density Profiles Large deviation in sound speed due to mismatch in CE boundary, determined by condition SpS 13 - IAUGA

  9. Convective Envelope Boundary RCZ=0.713±0.001 R8 Basu & Antia 2004 (and many before) SpS 13 - IAUGA

  10. Surface Helium Abundance Partial ionization zones leave imprints on G1 HeII dip used to determine surface Y (modulo EOS & other contributions e.g. OIII) YS in the range 0.24-0.25 Adopt YS=0.2485±0.0034 SpS 13 - IAUGA

  11. Solar Abundance Problem Summarizing results Helioseismology favours higher solar metallicity (GS98-like) SpS 13 - IAUGA

  12. Other Helioseismic Probes Using combinations of frequencies Roxburgh & Vorontsov 2003 Large separations Small separations SpS 13 - IAUGA

  13. Other Helioseismic Probes Using directly combinations of frequencies Roxburgh & Vorontsov 2003 Small separations ratios insensitive to surface effects Basu et al. 2007 SpS 13 - IAUGA

  14. Other Helioseismic Probes Deficit due to low helium core abundance in low-Z models (also degenerate with opacities) SpS 13 - IAUGA

  15. Abunds from Seismic constraints Sensitivity of YS, RCZ and dc to element abundances Change Ne/O ratio, keep YS & RCZ YS-YS(Hel) R/Rsun RCZ-RCZ(Hel) O= 8.86±0.04 Ne=8.15±0.17 Fe= 7.50±0.05 Not surprisingly very close to GN93 or GS98 values Using either model as reference SpS 13 - IAUGA

  16. Abunds from Seismic constraints A more integrated approach including neutrino fluxes (pp, pep, 8B, 7Be) and a radial profile for the sound speed (not just <dc>) Two treatments of opacity uncertainty dk/k=0.025 (CNO)-(CNO)AGSS09= 0.18±0.02 dex (NeMg)-(NeMg)AGSS09= 0.10±0.05 (SiS)-(SiS)AGSS09= 0.12±0.03 (Fe)-(Fe)AGSS09= 0.00±0.16 Villante et al. in prep. kOP-kOPAL (CNO)-(CNO)AGSS09= 0.15±0.03 (NeMg)-(NeMg)AGSS09= 0.17±0.06 (SiS)-(SiS)AGSS09= 0.05±0.06 (Fe)-(Fe)AGSS09= -0.02±0.05 Differences in results highlight necessity for proper opacity uncertainties SpS 13 - IAUGA

  17. Solar Abundance Problem However... from solar modeling point of view, all previous results are degenerate with stellar opacities Low-Z model + increased k Christensen Dalsgaard et al 2009 All helioseismic probes discussed before are recovered if opacity is increased SpS 13 - IAUGA

  18. How Much Opacity Needed? Christensen Dalsgaard et al. 2009 Dk~20-30% at RCZ Dk~3-5% at the core SpS 13 - IAUGA

  19. How Much Opacity Available? OPAS vs OP (blue) OP vs OPAL Blancard et al. 2012 Badnell et al. 2005 Large differences for indiv. elements but compensation Dk~2% at RCZ Dk<4% at any radii Dk~2-3% at RCZ Dk~1-% at the core SpS 13 - IAUGA

  20. Opacity Independent Probe Partial ionization of metals at R < 0.98R8 NeIX OVII NVI CV Li et al. 2007 Difference in G1 depends on EOS SpS 13 - IAUGA

  21. Opacity Independent Probe Partial ionization of metals at R < 0.98R8 NeIX OVII NVI CV Some sensitivity on individual elements, e.g. C & O SpS 13 - IAUGA

  22. Solar Neutrinos 8B precisely determined 3% - used as a thermometer Combining expressions for 13N and 15O, including experimental sensitivity & neutrino oscillations (Haxton & Serenelli 2008) • SSM only used as a reference point (and exponents) • Exponents ‘robust’ to variations in solar model inputs • Uncertainty dominated by experimental (S17 & S1 14) contributions • “Perfect” CN measurement gives central C+N to about 12% Using Borexino upper limit for F(13N+15O): X(C+N)Borexino< 0.0072 X(C+N)GS98= 0.0048 -- X(C+N)AGSS09= 0.0039 SpS 13 - IAUGA

  23. Summary Solar models with high-Z (GS98-GN93; CNO but also others) is much more consistent with seismic inferences of solar structure than low-Z models Almost all seismic probes of metallicity are degenerate with radiative opacities Exception is G1 due to partial ionization of metals – signal small and interpretation depends on EOS Opacity changes needed >> than systematic differences, no actual information on internal uncertainties Inversion of the problem: using seismic probes to extract composition leads to results similar to high-Z compositions. Treatment of opacity uncertainties unclear and crucial Solar neutrinos for core C+N can be competitive in 2-3 years SpS 13 - IAUGA

More Related