… this could be a poem…

In another dimension, this could be a poem. I found it somewhere and now I forget…

This movie shows the elemental abundances for the calculation. The white curve is the actual network abundance distribution. The green curve is the NSE abundance distribution computed at the same temperature, density, and electron fraction. The red curve is the QSE abundance distribution at the same temperature, density, electron fraction, and abundance of heavy nuclei. The matter begins with pure neutrons and protons. As the temperature falls, nucleons assemble into higher-mass nuclei. The network follows NSE down to about T9=6.5. Below this temperature, the reactions that assemble heavy nuclei from alpha particles become too slow to maintain the NSE. Nevertheless, the most abundant nuclei remain in a nearly exact QSE down to about T9=5. At this point, the QSE begins to favor Sn isotopes (Z=50), but the charged-particle reactions that would carry the actual network abundances are too slow, so the network and QSE abundances diverge. With decreasing temperature, the network and QSE abundances increasingly diverge. By the end of the movie, the network, QSE, and NSE abundances are all very different. The network nuclear populations have now largely broken down into (n,gamma)-(gamma,n) equilibrium in which isotopes of a given element are in equilibrium under exchange of free neutrons but isotopes of different elements are completely out of equilibrium with each other.

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