# I Variations in the speed of sound in a star

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1. Sep 11, 2018

### fab13

I try to understand the following graphics with x-axis being the radius of a typical star :

I would like to knwo if $\delta c/c$ (y-axis) represents the relative error between theorical and experimental values or if it represents the fluctuations of speed of sound inside. If these are fluctuations, one could get the mean speed all over radii or standard deviation.

I am not sure what it is exactly.

Any help is welcome

Last edited by a moderator: Sep 11, 2018
2. Sep 11, 2018

### Staff: Mentor

Can you give the source link? Even when using the Upload feature to attach a figure to your post, it is a good practice to post the source link. It also helps to avoid copyright issues. Thanks.

3. Sep 11, 2018

### fab13

lecture is available on this link

4. Sep 11, 2018

### Tom.G

That's it. As explained in the graph on the previous page of the presentation you linked.

5. Sep 12, 2018

### fab13

So the main discrepancy in current models is in the zone 0.4 - 0.65 R/R0 : can anyone could explain what's the origin of this issue ?

at R = 0.4 - 0.65 R0, are we in radiative or convective zone ?

Regards

6. Sep 12, 2018

### fab13

Could anyone help me on this current discrepancy ? or if someone had stellar physics knowledge ... thanks