limits on solar cno from helioseismology @special session 13 iau - xxviii ga aldo serenelli

Limits on Solar CNOFrom Helioseismology

@Special Session 13IAU - XXVIII GA

Aldo SerenelliInstitute of Space Sciences (CSIC-IEEC)

Bellaterra, Spain

Beijing – 28.08.12 SpS 13 - IAUGA

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

Solar Abundances

Solar abundances

log EX= log (NX/NH)+12

Two paradigmatic sets

Differences

New 3-D hydrodynamic models of solar atmosphere

NLTE treatment of some elements

Refined selection of lines (e.g. identification of blends)

Reduction of CNO(Ne) ~ 30-40%


GS98: Grevesse & Sauval (1998)AGSS09: Asplund et al. (2009)

GS98 or GN93 representative of high-Z comp.

AGSS09 or AGS05 representative of low-Z comp.

Metals Matter in Solar Interior


Large contribution to rad. opacity (between 30 to 80%)

O most important individual contributionRadiative temperature gradient temperature stratification in radiative interior

Contribution (minor) to EOS

Changes in nuclear rates, particularly CNO rates

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

Helioseismic Probes


Acoustic modes --- structural quantities: p, , 1, c2 can beobtained “directly”Modes characterized by (n,l,m) Different modes sample the solar interior differentlyInner turning-point radius determined by

Helioseismic Probes


Inversions: take two independent variables from the pool (p, , c2, 1) e.g. c2,

or c2,

and construct radial profiles

Sound and Density Profiles


Large deviation in sound speed due to mismatch in CE boundary, determined by condition

Convective Envelope Boundary


RCZ=0.713±0.001 R8

Basu & Antia 2004 (and many before)

Surface Helium Abundance


Partial ionization zonesleave imprints on 1

HeII dip used to determinesurface Y(modulo EOS & othercontributions e.g. OIII)

YS in the range 0.24-0.25

Adopt YS=0.2485±0.0034

Solar Abundance Problem


Summarizing results

Helioseismology favours higher solar metallicity (GS98-like)

Other Helioseismic Probes


Using combinations of frequencies

Roxburgh & Vorontsov 2003

Large separations Small separations



Using directly combinations of frequencies

r

dr

dr

dc

nr

nrR

nn

nn

nn

nn

0

0,0,1

3,11,13

1,11,

2,10,02

)(

)(

Roxburgh & Vorontsov 2003

Basu et al. 2007

Small separations ratiosinsensitive to surfaceeffects



Deficit due to low helium core abundance in low-Z models(also degenerate with opacities)

Abunds from Seismic constraints


Sensitivity of YS, RCZ and c to element abundances

RCZ-RCZ(Hel)

YS-Y

S(H

el)

R/Rsun

Change Ne/O ratio, keep YS & RCZ

O= 8.86±0.04Ne=8.15±0.17Fe= 7.50±0.05

Using either model as referenceNot surprisinglyvery close to GN93or GS98 values

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

(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

=0.025

(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

OP-OPAL

Villante et al. in prep.

Differences in results highlight necessity for proper opacity uncertainties

Solar Abundance Problem


However...

from solar modeling point of view, all previous results are degenerate with stellar opacities

Low-Z model + increased

All helioseismic probes discussed before are recovered if opacity is increased

Christensen Dalsgaard et al 2009

How Much Opacity Needed?


~20-30% at RCZ~3-5% at the core

Christensen Dalsgaard et al. 2009

How Much Opacity Available?


~2-3% at RCZ~1-% at the core

OP vs OPAL OPAS vs OP (blue)

Badnell et al. 2005 Blancard et al. 2012

Large differences for indiv. elements but compensation~2% at RCZ<4% at any radii

Opacity Independent Probe


Partial ionization of metals at R < 0.98R

CV

NeIX

OVII

NVI

Difference in 1 depends on EOS

Li et al. 2007

Opacity Independent Probe


Partial ionization of metals at R < 0.98R

Some sensitivity on individual elements, e.g. C & O

Solar Neutrinos


8B precisely determined 3% - used as a thermometerCombining 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 (13N+15O): X(C+N)Borexino< 0.0072

X(C+N)GS98= 0.0048 -- X(C+N)AGSS09= 0.0039

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 withradiative opacities

Exception is 1 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 compositionleads to results similar to high-Z compositions. Treatment of opacityuncertainties unclear and crucial

Solar neutrinos for core C+N can be competitive in 2-3 years

limits on solar cno from helioseismology @special session 13 iau - xxviii ga aldo serenelli

Documents

condition sps

low solar metallicity

solar interiorbeijing

solar cnofrom helioseismology

z comp

low helium core abundance

ags05 representative

lowz modelsalso degenerate