okay, i have a seemingly silly question, what is the order of fusion in a star - i know that hydrogen goes to helium...but then i get a bit lost... And that is pretty darned fast VanderL!

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art

Wait a minute Tinaa,
FG Sagittae is in a supernova remnant itself, does that mean a star can go supernova twice?
I still don't understand how a powersource of a giant star can turn it's fusion engine down and cooling from 50,000 K to 4,000 K in a few decades. Current wisdom is that in our Sun it takes 100,000 years for heat to get from the core to the surface. Or are the implications that in variable stars the heat source is only at the surface, in which case the electric model makes more sense, since it poses that all the energyconversion happens exactly at the surface.
Damienpaul, it isn't strange that you have trouble remembering all the different steps in the fusion model, there's so many steps, I'll try to find the correct sequence that is thought to act in our Sun's core.

Damienpaul, my view is of course that nuclear fusion is not the powersource of a star so the next bit is a "colored" version of the fusion process (taken from Wal Thornhill's website).
http://www.holoscience.com/news/puzzle.html
Here the proton-proton reaction is described and also how improbable this fusion recation is.
The neutrino's generated in this way are too low-energy to detect, so there is a side chain of fusion that produces detectable neutrino's (involving 3 He and 4 He particles to form a beryllium nucleus (7 Be) which then captures a proton to form a boron nucleus (8 B); this nucleus then breaks up into Beryllium (8 Be) plus a positron and neutrino).
He argues that the neutrino detection that shows only a third of the expected number, is correct (so no neutrino-oscillation fudging is necessary) and means that fusion is not an important process in the Sun. Furthermore, the fact that neutrino numbers vary with the solar (sunspot) cycle indicates that the fusion is not to be found in the Sun's core, but at it's surface.
Hope this helps, some googling will show the rest of the fusion reactions for the heavier elements.
Maybe I can add that the easiest way to produce heavier elements is through an electrical plasma pinch device.
Cheers.

Thank you VanderL - it is actually clear to me now, well the first part as described. Ok I bite, what is the electrical plasma pinch device?

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art

http://public.lanl.gov/alp/plasma/universe.html

Here is the site of Anthony Peratt explaining how plasma works, there is a section called Laboratory Astrophysics where all kinds of devices are mentioned, basically the Z-pinch machine is what plasma physicists use to get a nuclear fusion reaction going. They do it efficiently by using electricity, and why would Nature do it any different (if nothing else, Nature is efficient). As I understand it, all the 60 elements found in the Sun's spectrum can be generated in this way.
Cheers.

which 60 elements...i know of hydrogen and helium, but what of the remaining 58??? :blink:

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art

http://csep10.phys.utk.edu/astr162/lect/su...omposition.html

Here is the list.
Cheers.

Helium Flashes. The heat flash causes the star's envelope to grow huge in 3 to 50 years. There are also different kinds of supernovae and then there are novae. Here is an example of a repeating nova.

Also check this out.

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Insanity: doing the same thing over and over again and expecting different results.
Albert Einstein

Thanks Tinaa,

I know there are a whole bunch of fusion processes, convection and expansion/contraction phenomena described to explain the zoo of star types and star properties. To me it seems that every star type has it's own specific set of characteristics that CAN be explained by the complex processes that are assumed. The problem to me is the lack of a logical mechanism that makes stars behave the way they do. There is never one process responsible for all the star properties that we can see (sometimes there is no fuel, sometimes there is too much fuel, sometimes gravity is responsible, sometimes magnetism etc). This seems like "epicycling" to me, everything is very complex and imo unnecessarily so. An example; recently a star was described (Arechnar) that is 50% flatter at the poles than at the equator. Theory did not expect this, so now a bunch of scientists are trying to explain this observation by modifying the theory and this will probably lead to a triumphant article very soon.
I think this has been going on for quite some time (every new observation is a new class of stars, like V838 Mons seems to be) and it means that we don't really know what makes a star shine and we should be prepared to accept that our current model is wrong and look for viable alternatives.
Cheers.

Here is a site that explains why the elcetric universe version of star formation is junk.

Check this one out too. It really takes apart the electric sun theory!

__________________
Insanity: doing the same thing over and over again and expecting different results.
Albert Einstein

So helium flashes could conceivably occur with our sun when it reaches a white dwarf?

Wow, that is some debunking of the electric universe theory.

__________________
Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art