What is the ratio of hydrogen to helium in the Sun?

[shirin]

Hi everyone,
There is problem that asks how many hydrogen atoms are there in sun for each helium atom.
I don't know which solution is correct:
1) to count all the hydrogens and heliums participating in one solar pp chain,
or,
2) as X=0.71 and Y=0.26, there is (0.71/0.26)*2 H for each He.
Thanks for help.

 

[qraal]

Hi everyone,
There is problem that asks how many hydrogen atoms are there in sun for each helium atom.
I don't know which solution is correct:
1) to count all the hydrogens and heliums participating in one solar pp chain,
or,
2) as X=0.71 and Y=0.26, there is (0.71/0.26)*2 H for each He.
Thanks for help.

The figures X & Y are mass fractions. In terms of numbers of atoms of each we need to divide by their relative masses, roughly 1:4, giving us 0.71 and 0.052, then divide those by the sum I.e. 0.71/0.762 & 0.052/0.762 which gives their atomic proportions. Divide the hydrogen figure by the helium figure and you have how many hydrogens for every helium.

 

[shirin]

thank you.

 

[phyzguy]

The 26% He by weight is more representative of the composition of the sun at the time of formation. The sun has been burning H to He for 4.5 billion years, so according to the standard solar model, the interior of the sun is now over 60% He. To calculate the atomic ratio, you would need to integrate over the whole volume - I don't know the answer, but I'm sure it is more than 26% He by weight when averaged over the whole sun. Here are a couple of references with Figure 2 in the first reference showing the mass fraction as a function of radius, and Table 1 in the second reference giving the He mass fraction in the core at >60%.

http://www.pha.jhu.edu/~france/PAPERS/solmodel.pdf

http://arxiv.org/abs/astro-ph/0204331

 

[pmacias]

I would like to provide some clarification on the abundance of hydrogen in the Sun. The Sun is primarily composed of hydrogen and helium, with hydrogen making up about 71% of its mass and helium making up about 26%. This means that for every 1 helium atom, there are about 2.7 hydrogen atoms in the Sun. This ratio is consistent throughout the Sun's interior, so both methods mentioned (counting all atoms involved in the solar pp chain or using the X and Y values) would result in a similar answer. However, it is important to note that this ratio may vary in different regions of the Sun, such as the outer layers where other elements may be present. Overall, the Sun is mostly made up of hydrogen, with smaller amounts of helium and other elements. I hope this helps clarify the abundance of hydrogen in the Sun.