In an earlier GQ thread a discussion arose how long it would take for a White Dwarf to cool down into a Black Dwarf (longer than the present age of the universe!) and the fact that a Neutron Star would cool down a lot more quickly.
Lets just say we are looking at a timescale of how long this white-hot ember of carbon and iron (right?) takes to go from vapor, condense to liquid, and finally crystalize as solid.
Don’t worry about the residual heat cooling down to Absolute Zero or anything. 
You’re asking what it would look like at different stages of the cooling process?
Sure.
A white-hot ball of gas…the outermost, coolest layer “raining” molten carbon/iron…eventually the gases liquefy into an ocean of molten carbon/iron building up a core of solid alloy which ends up a red-hot solid.
So. for a dwarf borne of a star like our sun, how long for the first drops of rain til the last liquid “freezes” to solid?
BTW, can neutronium have Gas/Liquid/Solid phase changes?
White dwarfs are never solid, liquid, nor gas, and their state depends very little on their temperature. And no, I’m not trying to “gotcha” with plasma; whether something is plasma is independent of whether it’s a gas.
To clarify: White dwarfs are fluid, but not all fluids are liquids or gases. It depends on the equation of state, which is the relationship between the pressure and density of the fluid. A liquid has the equation of state density = constant . A gas has the equation of state density = pressure*constant/temperature . But there are many other possible equations of state, and the equation of state of white dwarf material isn’t either of those.
yes, but a WD is no longer creating new heat… just shedding the energy from its former life of nuclear fusion.
Sooner or later, it cools enough that it takes on familiar, non exreme-heat physical and even chemical attributes.
This timeline may be of interest: Timeline of the far future - Wikipedia
Goodness, no. The pressures in white dwarfs are far too high. It’s always a very strange form of matter. On formation, it’s something like a strange fluid, made of very soft spheres (the nuclei, interacting with nearly their full 1/r Coloumb repulsion) at very high densities, embedded in a background which is a nearly degenerate gas of fermions (the electrons), which provides the enormous pressure needed to stave off gravity. As it cools, the thinking is that the nuclei form what’s called a Wigner crystal inside the degenerate gas of fermions (which actually becomes a relativistic degenerate gas, since the typical velocities of the electrons becomes close to the speed of light). The Wigner crystal is basically a close-packed crystal (hcp or fcc), like most metals form, but the force of repulsion is the soft 1/r Coulumb force. Anyway, it pretty much never behaves anything like ordinary matter. (For example, if you throw some extra mass on it, it gets smaller, not larger.) You can still talk about it being liquid and solid, because whether it has long-range order or not is question that can be answered. I wouldn’t say there is any obvious analogy to the gas-liquid transition, though.
Yeah, when we model white dwarfs and neutron stars, even brand-new ones, we describe them as being at zero temperature. Even a temperature of millions of degrees is negligible compared to the other phenomena going on in the star.
Search is failing me; can you provide a link to this thread?
search failed me, too
Approx 10[sup]15[/sup] years for the Sun.