If the proportion of the sun that is helium were shifted to 100%, but the sun\'s
ID: 1770821 • Letter: I
Question
If the proportion of the sun that is helium were shifted to 100%, but the sun's mass is held to be one solar mass (i.e. if we hold the mass to be the same) how would the structure of the sun change? I.e. how would things like size, luminosity, etc. change? I would appreciate an answer with as much depth as possible but there is no need to make any calculations (though explaining how basic equations like the four equations of state would play certain roles would be appreciated too). Thank you so much!
Explanation / Answer
if proportion of helium was shifted to 100%
then, the radius of sun would decrease, as mass density of helium is greater than hydrogen
Luminosity will also decrease as the triple alpha process gives off more energy as compared to just helium fusion
so less energy will be output by the sun thereby reducing its luminosity
the color of the sun will change as well as hydrogen fusion creates photons of different wavelength as compared to helium fusion, and this color will be shifted in the spectrum towards longer wavelengths ( reddish colour)