Egg Mixer – stars that are almost uniformly mixed inside

I was watching a video about an “egg mixer”. It spins a raw egg, reverse direction, spins and reverses. The yolk and white become scrambled and uniform. When you boil the eqgs they come out already scambled and boil. The motive is that kids often do not eat the whites because they are fairly tasteless.

But when I was watching, I had in mind neutron stars, hydrogen burning stars, and multilayer older stars and planets near to dense stars like neutron stars. There must be common situations where a planet might speed up or slow down its rotation. Or a star or a molecular cloud would speed up its rotation or slow down. I can think of a few.

My point is that our models of stellar evolution are based on a fairly passive and quiet gravitational densification, some material in the core of a star reaching ignition temperature and pressure. The nova models all have these neat and perfect spherical shells. But when I watch the videos of the sun in different wavelengths the surface is infinitely complex and turbulent. I can see in the center of a galaxy where there are many complex and intersecting orbits of things, there is much potential for near collisions, and situations where a star could be “spun up” “spun down” and the internal layers mixed quite thoroughly.

Now, every time something like this comes to mind, I will think about it for a while, and often just by taking a moment to let my internal imaging system work, I can just watch most of the relevant processed. As you mentioned each process, I could see the hundreds of times I have seen video, read papers and generated visualizations, diagrams that I animate, blackboard drawings that I animate, words read or heard that I convert to 3D volumetric visualization.

If you say “merger”, I can watch a variety of those collisions and merges evolve. Since my recorded memories are often taken from reality, the visualizations are scaled models of real things.

BUT. After a short time I get serious and either start methodically searching the web, or I think “How can I capture or write down or generate these so this momentary casual interest that I might only spend a few hundred hours on, would be more completely handled and share with all humans on the Internet.

“mixing” (“stellar model” OR “stellar models” OR (“nucleosynthesis” “stars”) OR (“stellar” “evolution”) ) has 210,000 entry points on Google

“One size does not fit all: Evidence for a range of mixing efficiencies in stellar evolution calculations” by C Johnston in Apr 2021

“mixing efficiencies” (“stars” OR “stellar”) has 9,070 entry points

“Internal mixing of rotating stars inferred from dipole gravity modes” by May G Pedersen and others

(“stars” OR “stellar”) “rotational acceleration” has 426,000 entry points
(“stars” OR “stellar”) “rotational acceleration” “mixing” has 32,500 entry points
(“stars” OR “stellar”) “deep mixing” has 32,300 entry points
(“stars” OR “stellar”) “core mixing” has 27,400 entry points

Larger stars are known to have core mixing. And partial nova events will slosh things around rather violently. But I thing that when galaxies merge, particularly when central regions of galaxies merge, that will have complexities orders of magnitude higher than simple “gravitation makes a star, stars burn, some star explode, some stars leave embers”.

I am fairly certain your idea of central black holes merging” is much more complex. All the evidence I have is that black holes, generally are NOT consolidated internally, and that is even more true of large ones. Rather they likely contain regions with many orbiting high density objects – simple black holes, neutron stars, white and brown dwarfs and even rather ordinary stars.

I won’t try to summarize. What I am realizing is that I could spend a million lifetimes studying the data from astronomical sensors and cosmological simulations. I might have my private views and ideas, but they are not particularly useful to anyone else, and because my brain is finite, I could never hold and give instructions that cover the complexity of what can happen, even inside our own sun, or a few billion stars I might happen to look at.

But perhaps I can try to index and summarize things in other ways. Not only for experts, but for all humans. I often feel that “these closed groups of a few ten thousand who lock themselves away from the rest of the world and spend their time as experts that no one reads their papers” is the wrong way to do science technology engineering mathematics computing and other professions.