Context : Constraining additional mixing processes and chemical composition is a central problem in stellar physics as their impact on stellar age determinations leads to biases in our studies of stellar evolution , galactic history and exoplanetary systems .
In two previous papers , we have shown how seismic inversion techniques could be used to offer strong constraints on such processes by pointing out weaknesses in current theoretical models .
The theoretical approach having been tested , we now wish to apply our technique to observations .
In that sense , the solar analogues 16CygA and 16CygB , being amongst the best targets in the Kepler field , are probably the current most well observed stars to test the diagnostic potential of seismic inversions .

Aims : We wish to use seismic indicators obtained with inversion techniques to constrain additional mixing processes in the structure of the components of the binary system 16Cyg .
The combination of various seismic indicators will help to point out the weaknesses of stellar models and thus implies more constrained and accurate fundamendal parameters for these stars .

Methods : First , we will use the latest seismic , spectroscopic and interferometric observational constraints in the litterature for this system to determine suitable reference models independently for both stars .
We will then carry out seismic inversions of the acoustic radius , the mean density and of a core conditions indicator .
These additional constraints will be used to improve the reference models for both stars .

Results : The combination of seismic , interferometric and spectroscopic constraints allows us to obtain accurate reference models for both stars .
However , we note that a degeneracy exists for these models .
Namely , changing the diffusion coefficient or the chemical composition within the observational values could lead to 5 \% changes in mass , 3 \% changes in radius and up to 8 \% changes in age .
We used acoustic radius and mean density inversions to further improve our reference models then carried out inversions for a core conditions indicator , denoted t _ { u } .
Thanks to the sensitivity of this indicator to microscopic diffusion and chemical composition mismatches , we were able to reduce the mass dispersion to 2 \% , namely \left [ 0.96 M _ { \odot } , 1.0 M _ { \odot } \right ] , the radius dispersion to 1 \% , namely \left [ 1.188 R _ { \odot } , 1.200 R _ { \odot } \right ] and the age dispersion to 3 \% , namely \left [ 7.0 , 7.4 \right ] , for 16 CygA .
For 16 CygB , t _ { u } offered a consistency check for the models but could not be used to reduce independently the age dispersion .
Nonetheless , assuming consistency with the age of 16 CygA could help to further constrain its mass and radius .
We thus find that the mass of 16 CygB should be between 0.93 M _ { \odot } and 0.96 M _ { \odot } and its radius between 1.08 R _ { \odot } and 1.10 R _ { \odot }

Conclusions :