Absolute Solar Abundances Absolute Solar Abundances From - - PowerPoint PPT Presentation

Absolute Solar Abundances Absolute Solar Abundances From From Helioseismology Helioseismology

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 Convection Zone Depth

– – Discontinuity in Temperature Discontinuity in Temperature Gradient Gradient – – Sharp Local Feature Sharp Local Feature

Surface Helium Surface Helium

– – Adiabatic Temperature Adiabatic Temperature Gradient reduced in the Gradient reduced in the presence of ionization presence of ionization – – 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 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 Cs Difference Fractional Radius

A Question of Atmospheres A Question of Atmospheres

1D Models (GS98) 1D Models (GS98)

– – Semi Semi-

• Empirical

Empirical Thermal Profile (HM) Thermal Profile (HM) – – Microturbulence Microturbulence Parameter Parameter – – No granulation No granulation – – NLTE corrections NLTE corrections added added

3D Models (A04, C08) 3D Models (A04, C08)

– – Theoretical Thermal Theoretical Thermal Profile Profile – – Line broadening from Line broadening from simulations simulations – – Granulation included Granulation included – – NLTE corrections NLTE corrections 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 dT/dr dT/dr related to related to κ κ κ κ related to abundance 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 Use photospheric photospheric data to constrain the data to constrain the 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

• n
• n Ysurf

Ysurf, , Rcz Rcz 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 +/ Fe/H = 7.50 +/-

• 0.045 +/

0.045 +/-

• 0.003 (

0.003 (CNNe CNNe) ) O/H = 8.86 +/ O/H = 8.86 +/-

• 0.041 +/

0.041 +/-

• 0.025 (

0.025 (CNNe CNNe) ) assuming GS98 O/Ne assuming GS98 O/Ne

Consistent with GS98, Consistent with GS98, C08; inconsistent with C08; inconsistent with A04 A04

Oxygen Iron

Can We Infer Neon? Can We Infer Neon?

Tough to measure! Tough to measure! For scalar quantities For scalar quantities CNONe CNONe are are degenerate degenerate However, Ne retains However, Ne retains electrons to higher electrons to higher temperatures than temperatures than

• xygen
• xygen

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 O/H – – 0.035 0.035 => O/H = 8.83 => O/H = 8.83

Delahaye & Pinsonneault 2009

Impact of Missing Physics Impact of Missing Physics

Mixing Mixing – – reduces the degree of settling reduces the degree of settling

– – 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 However, a significant subadiabatic subadiabatic 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 May slightly reduce interiors-

• based O

based O abundance (up to 0.03 abundance (up to 0.03 dex dex) )

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 Depression of the Depression of the adiabatic gradient adiabatic gradient from metal ionization from metal ionization seen ( seen (Antia Antia & & Basu Basu 2006; Chaplin et al. 2006; Chaplin et al. 2007) 2007) Zcz Zcz = 0.017 +/ = 0.017 +/-

• 0.002

0.002 Consistent with the Consistent with the high abundance scale high abundance scale

Sound Speed Gradient

What Could Be the Issue with What Could Be the Issue with Atmospheres? Atmospheres?

Theoretical thermal Theoretical thermal structure from structure from Asplund Asplund et al. is too cool et al. is too cool compared with solar compared with solar limb limb-

• darkening data

darkening data Atmosphere models Atmosphere models should be calibrated should be calibrated

• n solar data
• n solar data

Overshooting in Overshooting in simulations is too simulations is too effective effective

Koesterke et al. 2008 Theoretical Models vs. Limb-Darkening Data

New Codes, New Results New Codes, New Results

Caffau Caffau et al. (2008) et al. (2008) 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+/ 8.76+/-

• 0.07,

0.07, 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 ( the solar mixture (Haxton Haxton & & Serenelli Serenelli 2008) 2008)

Simulations Simulations Experimental Experimental Opacity Opacity Measurements Measurements for Solar for Solar Conditions Conditions (Bailey et al. (Bailey et al. 2007, 2008) 2007, 2008)