Absolute Solar Abundances Absolute Solar Abundances From Helioseismology Helioseismology From Marc Pinsonneault Marc Pinsonneault Ohio State University Ohio State University Collaborator: Delahaye
Precision Astrophysics Precision Astrophysics Requires Requires Precise Abundances Precise Abundances Chemical Evolution Chemical Evolution Stellar Ages Stellar Ages Mixing and Stellar Physics Mixing and Stellar Physics Powerful diagnostics available in the solar Powerful diagnostics available in the solar atmosphere and interior atmosphere and interior New generation of model atmospheres New generation of model atmospheres
Powerful Seismic Constraints Powerful Seismic Constraints Convection Zone Depth Surface Helium Convection Zone Depth Surface Helium – Discontinuity in Temperature Discontinuity in Temperature – Adiabatic Temperature Adiabatic Temperature – – Gradient Gradient Gradient reduced in the Gradient reduced in the presence of ionization presence of ionization – Sharp Local Feature Sharp Local Feature – – – Degree depends on Degree depends on abundance abundance Basu & Antia 2008 Sound Speed Gradient Precise Localization of the CZ depth is possible
The Solar Abundance Problem The Solar Abundance Problem GS98 [O/Fe] = 8.83 GS98 [O/Fe] = 8.83 A04 [O/Fe] = 8.66 A04 [O/Fe] = 8.66 Lower solar Lower solar Fractional Cs Difference abundances degrade abundances degrade agreement with all agreement with all seismic observables: seismic observables: – Surface Y Surface Y – – CZ depth CZ depth – – Sound Speed Sound Speed – Fractional Radius
A Question of Atmospheres A Question of Atmospheres 1D Models (GS98) 3D Models (A04, C08) 1D Models (GS98) 3D Models (A04, C08) – Semi Semi- -Empirical Empirical – Theoretical Thermal Theoretical Thermal – – Thermal Profile (HM) Profile Thermal Profile (HM) Profile – Microturbulence Microturbulence – Line broadening from Line broadening from – – Parameter simulations Parameter simulations – No granulation No granulation – Granulation included Granulation included – – – NLTE corrections NLTE corrections – NLTE corrections NLTE corrections – – added added added added
Can We Turn the Problem Can We Turn the Problem Around? Around? OPACITY OPACITY Sound Speed Sound Speed measurements constrain measurements constrain the temperature gradient the temperature gradient κ related to κ dT/dr related to dT/dr κ related to abundance κ related to abundance Bailey et al. 2008
Predicting Abundances Predicting Abundances Use meteoritic data to infer the ratio of Use meteoritic data to infer the ratio of heavy metals to one another (good to 0.01 heavy metals to one another (good to 0.01 dex) ) dex Use photospheric photospheric data to constrain the data to constrain the Use ratio of C, N, Ne to O. ratio of C, N, Ne to O. For a given physical model solve for the For a given physical model solve for the heavy + light metal combination with the heavy + light metal combination with the closest agreement to the seismic data closest agreement to the seismic data
Abundances Impact Seismic Abundances Impact Seismic Properties Properties Surface Helium Surface Helium constrains core L constrains core L (Fe) and diffusion (Fe) and diffusion Surface Surface Convection Zone Convection Zone depth constrains depth constrains envelope opacity envelope opacity (CNONe CNONe) ) ( Delahaye & Pinsonneault 2006
Establishing Theoretical Errors Establishing Theoretical Errors Compute Compute impact of impact of uncertainties in uncertainties in input physics input physics on Ysurf Ysurf, , Rcz Rcz on Implies a Implies a theoretical error theoretical error along with along with measurement measurement uncertainties uncertainties
Mapping Thermal Structure Onto Mapping Thermal Structure Onto Abundances Abundances For either mix of For either mix of elements one predicts elements one predicts Fe/H = 7.50 +/- - 0.045 +/ 0.045 +/- - Fe/H = 7.50 +/ 0.003 (CNNe CNNe) ) 0.003 ( Iron O/H = 8.86 +/- - 0.041 +/ 0.041 +/- - O/H = 8.86 +/ 0.025 (CNNe CNNe) ) 0.025 ( assuming GS98 O/Ne assuming GS98 O/Ne Consistent with GS98, Consistent with GS98, C08; inconsistent with C08; inconsistent with A04 A04 Oxygen
Can We Infer Neon? Can We Infer Neon? Tough to measure! Tough to measure! For scalar quantities For scalar quantities CNONe are are CNONe degenerate degenerate However, Ne retains However, Ne retains electrons to higher electrons to higher temperatures than temperatures than oxygen oxygen High Ne/Low O High Ne/Low O inconsistent with the inconsistent with the sound speed profile sound speed profile
An Additional Step An Additional Step Construct models Construct models which reproduce which reproduce the scalar the scalar constraints with constraints with varying Ne/O. varying Ne/O. Evaluate Cs Evaluate Cs profile profile Ne/H = +0.1 => Ne/H = +0.1 => O/H – – 0.035 0.035 O/H => O/H = 8.83 => O/H = 8.83 Delahaye & Pinsonneault 2009
Impact of Missing Physics Impact of Missing Physics Mixing – – reduces the degree of settling reduces the degree of settling Mixing – Shallower Surface CZ (bad!) Shallower Surface CZ (bad!) – – Higher Surface Y (good!) Higher Surface Y (good!) – – 25% reduction in settling is consistent with 25% reduction in settling is consistent with – lithium depletion constraints; included in base lithium depletion constraints; included in base case. case. What about convection? What about convection?
Convective Overshoot? Convective Overshoot? Overshooting would deepen the surface Overshooting would deepen the surface convection zone seen by seismology convection zone seen by seismology However, a significant subadiabatic subadiabatic However, a significant gradient would soften the sharp gradient would soften the sharp discontinuity in sound speed gradient discontinuity in sound speed gradient Not seen in data; overshoot < 0.05 Hp Not seen in data; overshoot < 0.05 Hp (Basu Basu 1997) => < 0.003 1997) => < 0.003 Rsun Rsun ( May slightly reduce interiors- -based O based O May slightly reduce interiors abundance (up to 0.03 dex dex) ) abundance (up to 0.03
Equation of State Test Equation of State Test Ionization lowers Ionization lowers the adiabatic the adiabatic temperature temperature gradient gradient Strength of the Strength of the effect proportional effect proportional to abundance to abundance
Confirming Evidence from The Confirming Evidence from The Equation of State Equation of State EQUATION OF STATE EQUATION OF STATE Sound Speed Gradient Depression of the Depression of the adiabatic gradient adiabatic gradient from metal ionization from metal ionization seen (Antia Antia & & Basu Basu seen ( 2006; Chaplin et al. 2006; Chaplin et al. 2007) 2007) Zcz = 0.017 +/ = 0.017 +/- - 0.002 0.002 Zcz Consistent with the Consistent with the high abundance scale high abundance scale
What Could Be the Issue with What Could Be the Issue with Atmospheres? Atmospheres? Theoretical thermal Theoretical thermal structure from Asplund Asplund structure from et al. is too cool et al. is too cool compared with solar compared with solar limb- -darkening data darkening data limb Atmosphere models Atmosphere models should be calibrated should be calibrated on solar data on solar data Overshooting in Overshooting in simulations is too simulations is too Koesterke et al. 2008 effective effective Theoretical Models vs. Limb-Darkening Data
New Codes, New Results New Codes, New Results Caffau et al. (2008) et al. (2008) Caffau found a different found a different abundance scale abundance scale with a different with a different treatment of treatment of convection convection Solar [O/H] = Solar [O/H] = 8.76+/- -0.07, 0.07, 8.76+/ compatible with compatible with interiors interiors
Towards Precise Interiors Towards Precise Interiors Abundances Abundances Solar Neutrinos Solar Neutrinos – Fluxes may be precise enough to constrain Fluxes may be precise enough to constrain – the solar mixture (Haxton Haxton & & Serenelli Serenelli 2008) 2008) the solar mixture ( Simulations Simulations Experimental Experimental Opacity Opacity Measurements Measurements for Solar for Solar Conditions Conditions (Bailey et al. (Bailey et al. 2007, 2008) 2007, 2008)
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