Why heavy elements don't sink

[BDanielMayfield]

In stars that is. I ask because stellar spectra show the atomic absorption and emission lines of both lightweight and heavy elements as well. The atoms that are causing these lines can't be from too deep in the star, or we wouldn't be able to detect them. So what holds the heavier elements up in the photospheres of stars?

I suspect that it is ionization, but is that all there is to it? Wouldn't a slightly ionized heavy atom still tend to sink?

Bruce

[neufer]

In stars that is. I ask because stellar spectra show the atomic absorption and emission lines of both lightweight and heavy elements as well. The atoms that are causing these lines can't be from too deep in the star, or we wouldn't be able to detect them. So what holds the heavier elements up in the photospheres of stars?

I suspect that it is ionization, but is that all there is to it? Wouldn't a slightly ionized heavy atom still tend to sink?

Space Shuttle Endeavour appears to straddle the stratosphere and mesosphere in this photo. "The orange layer is the troposphere, where all of the weather and clouds which we typically watch and experience are generated and contained. This orange layer gives way to the whitish Stratosphere and then into the Mesosphere."

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In star radiative zones ionized (heavy) atoms will indeed be pushed out. (Ionized hydrogen & helium are just protons & alpha particles that are relatively poor at absorbing light.)

In star convective zones (which dominate the volume of all stars) atoms end up completely mixed.

In our own atmosphere, the heavy CO₂ molecule is a well mixed (at ~400 ppm and rising) throughout the Troposphere, Stratosphere and Mesosphere thanks to convection.

[BDanielMayfield]

Thanks Art. That well explains why even the heaviest elements are observed in stars' photospheres.