Re: Article: "Sun is Mostly Iron, Not Hydrogen"

From: Mike Lorrey (
Date: Thu Jan 10 2002 - 10:43:47 MST

Reason wrote:
> It's a fascinating process, the aging of stars. You start off fusing
> hydrogen to helium in the core. Then you run out of hydrogen, and the fusing
> moves to an expanding shell. The inner helium core grows and collapses
> without the sustaining radiation pressure of fusion reactions until it gets
> hot and dense enough to ignite. Which it does pretty much all at once. Bang!
> Helium fusion generates much more energy, so the star expands to a new
> equilibrium. Now you have a helium fusing core surrounded by a hydrogen
> fusing shell.
> Later on, you start to run out of helium, and build up a carbon core. So the
> start have a shell of helium fusion and a shell of hydrogen fusion outside.
> As the core gets larger, it collapses until it ignites with carbon fusion.
> Bang!
> The process of getting from a helium core ignition to a carbon core ignition
> is somewhat faster than getting a helium core ignition.

So what happens during planetary formation when a dozen or so
planetesimals get chucked into the sun by orbital resonances? Doesn't
the addition of preexisting heavy elements tend to spike the cocktail of
stellar development?

Furthermore, I haven't heard you or anyone speak to Jeff's earlier
calculation that there was something like 535 Earth masses of iron in
the Sun, based on the 0.15% iron content in the solar corona. Is this
accurate? If so, how does the presence of this amount of iron (and any
other metals) spike the Sun's development?

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