Monday, April 16, 2012

How to make iron (7) Super giants

© Ivan Eder
Red supergiant, Antares is about 850 times the diameter of our own Sun, 
15 times more massive, and 10,000 times brighter
in the yellowish cloud it has created

It is not so easy to make iron - not even to God of Israel - judging from what it takes to get it done.

The next step according to our study of how it is done is related to the mass of the star - if the star is more than ten times the mass of Sun it does not come a regular Red giant but something else happens and it becomes a Supergiant.

Super & giant.. two BIG words.

Professor James B. Kyler explains in his web page the receipt for making silicon and sulfur (not yet iron):

Supergiants are so massive, in spite of great mass loss through huge winds, that nuclear fusion can proceed farther than it can in ordinary giants.

When the helium runs out, the carbon and oxygen mixture compresses and heats, causing it to fuse to a mixture of neon, magnesium and oxygen.

Hydrogen and helium fusion had already moved outward into nested shells around the core.

When carbon fusion dies out in the core, leaving a mix of neon, magnesium, and oxygen, it too moves outward into a shell.

The neon-magnesium-oxygen mixture now in the core then heats and fuses into a mix of silicon and sulfur, each fusion stage taking a shorter period of time.

Not yet there but almost!

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