Sun question...

[Royston]

I've just been learning solar radiation distribution and it's effects on our environment (as infrared transfers) however it stated the solar luminosity is 70% 4600 Ma ago to what it is now. I guess that a lot of energy is being absorbed due to the strong gravititational field of the Sun, but why doesn't it just keep gaining energy.

 

Is it due to the half-life of the Sun's core...I'm really not up on nuclear reactions et.c so that might be nonsense, but what kick's starts the energy depletion to warrant the demise of our Sun into a white dwarf...why is it that it's gaining energy to sustain itself, and then the reverse happens ?

 

Sorry if this seems a daft question.

[RyanJ]

Is it due to the half-life of the Sun's core...I'm really not up on nuclear reactions et.c so that might be nonsense' date=' but what kick's starts the energy depletion to warrant the demise of our Sun into a white dwarf...why is it that it's gaining energy to sustain itself, and then the reverse happens ?

 

Sorry if this seems a daft question. [/quote']

 

Well, the sun does not turn strait into a white dwarf, it first turns into a red giant. This is when the sun has all butru out of hits Hydorgen fuel and starts to fuse Helium etc. (Some stars do this to Iron but thr sun is not big enough). at this point it gets hotter and lardr. After this itsnucler fuel is gone so its intenal force is weakned and it is then crushed by gravity to a white dwarf.

 

So basically it happens because of fuel depletion

 

Cheers,

 

Ryan Jones

[Royston]

Thanks for the response Ryan J. So if the Sun is getting hotter because it's fusing hydrogen from it's own reserves, is it safe to say that the Sun is not gaining luminosity through obtaining energy externally...pulling in matter from space. Again sorry if this seems obvious...it just struck me as odd at first...that it gets hotter, then cooler.