Fussion in our sun

[jordan]

I was in physics today and saw on a video a breif desription of stars forming heat throught the fussion of elements in their core. This brought about three questions.

 

1. Does anyone know whether the fussion in the core is balanced or sparadic? I mean, are there spots of hydrogen, some of helium, some of the next element (sorry, I don't know it off the top of my head) or does it fuse all the hydrogen, then all the helium and so on?

 

2. Does anyone know what state of this process the sun is in?

 

3. How would one be able to tell that this happens in the stars?

[Crash]

Well

Q1)...........? I think your talking about iron being the element

Q2). Its said to be in the yellow giant stage if i can remember correctly -> red giant, then either white dwarf or supernovae

q3). haven't got time enough to write this down, but observations (of other stars) help

[jordan]

Well

Q1)...........? I think your talking about iron being the element

 

Iron is the last element that a star's core can acheive. There are a few others in between' date=' but i don't remember if it is strictly doubling of the atomic number or if there are other factors. I was just wondering if it reaches each new element all at the same time or not.

 

Q2). Its said to be in the yellow giant stage if i can remember correctly -> red giant, then either white dwarf or supernovae

 

I know this hinges on the previous question, but do you know what elements would be in the sun at this phase?

 

q3). haven't got time enough to write this down, but observations (of other stars) help

 

That's alright. Thanks to you and an advanced thanks to all those who post later.

[greg1917]

Bismuth is the last element a star can produce via the s-process of element nucleosynthesis. Beyond this, supernovae are needed to make elements past z=83. This means the uranium deposits on earth must have been come from by a supernova explosion somewhere in the galaxy that threw material over to our side of the cosmos.

 

Iron is the last element that is produced via 'regular' element fusion. Iron inhabits the peak of the binding energy per nucleon vs mass number graph, so will not fuse as doing so would actually absorb heat from the star core.

 

Evidence can be seen from the spectrum of our sun, and other stars.

[swansont]

Does anyone know whether the fussion in the core is balanced or sparadic? I mean' date=' are there spots of hydrogen, some of helium, some of the next element (sorry, I don't know it off the top of my head) or does it fuse all the hydrogen, then all the helium and so on?

[/quote']

 

Due to the electrostatic repulsion of these nuclei, more energy is required to get the heavier ones to fuse, so they require higher temperatures. So there is a progression, although not all of the previous element is used up, so there will still be H around further out in the star when a star starts fusing He, and that H can certainly still fuse if it's hot enough.

 

But the core will have to be essentially tapped out of H so that it collapses under the gravitational force. The the pressure and temperature go up until He starts fusing, and it stabilizes again.