a few thoughts on the pocket universe:
- def a pocket universe, though in a distinctly mundis mundis way. planets, stars, etc- though temperatures are rather drastically limited, maybe a range between -60 and +260 celsius? it still works for heat propagation because....
- aether-like substance holds solar systems together, and allows heat to spread mostly evenly through the system. it gets "ragged" past a certain distance (depends on star color, possibly also something as analogue for giant/dwarf?)
- this aether is actually the third-most basic form of matter: intergalactic aether shades into galactic aether shades into aether shades into dense aether shades into atmosphere shades into solids and liquids... shades into whatever gives planets and such gravity. depending on how much gravity there already is, things get more smushed- asteroids into solid/liquid planetoids into solid/liquid planets into gas planets into plasma into weird shit.
- stuff that's smushed can't get unsmushed, except for in extenuating circumstances.
- stars evolution: say a gas planet or two get smushed together. or similar with other stuff. or a cloud of aether sloowly condenses on its own (this takes thousands of years). when the plasma ignites it blows nearby matter into orbits, where it condenses (this takes hundreds of years). theres lots of stuff (dust and such) flying around- most of the time this will hit stars directly, less and less likely to hit smaller stuff.
this changes a stars color as its mass increases (rolls right up the rainbow from purple to green to red and, theoretically, again and again), which also takes thousand of years. the mass increase basically just changes the color and therefore the radius of its aether stuff. as this progresses the dense aether grows thicker and it becomes more likely that matter will be flung away or stuck in an orbit, which can form new planets sometimes. but as time goes on the stars heat threatens to drop, which causes it to contract....
without changing its mass or heat. as this goes on over tens of thousands of years, it gets smaller and smaller and less good at maintaining its heat, which becomes irregular... then flickers... then stops. (the middle phases can be prolonged if theres another star in the same aether field thing) stuff keeps getting caught near it by its aether, but once this phase is reached the star is a sphere-with-a-disc-around-it of compressed, nonshining plasma.
there are various forms of this and while the heat isn't a problem it's hard to study because it is rather hard to get on and off without breaking things. as things swing by the increasingly odd star, they enter deeper and deeper aether fields... and without hitting they can be transformed into long arcs of matter with aether condensing right onto them. these can get stuck in orbit or even in place, and the star can sometimes be fully surrounded by these- which, if enough stuff enters the system (very rare!) can ignite into a new, shell-shaped star.
but as the star in the center compresses further... eventually the gravity becomes so much that parts of the star start flying through each other. this is the prelude to explosion, and takes a few days at maximum. even as things are becoming intangible, the matter shrinks further and further... until it flies through at galaxy-crossing speeds. at these speeds, where a galaxy is crossed in seconds and the distance between galaxies in minutes, things get weird. the ultra-dense star matter can run back through its history in a way- from weird shit of various forms, most often skipping plasma, back into planets or asteroids or aether clouds.
these chunks can slow down because of aether, but are too fast to be tangible- some ships have reported their microstar drives becoming microplanetary, leaving them in an odd position before the drive can be reconfigured. the ultimate destiny of many of these is to be captured by a nascent star, either into an orbit or as more color fuel.
a star lifetime is between about ten thousand and two hundred thousand years, but there are always other stars and there are ways to move planets
matter can vary in shape but the most common is a sort of iapetus-walnut shape. stars start out fully spherical, but as you get smaller they mostly trend towards that sphere-with-an-equatorial-disc-thing. asteroids are amalgams of those, especially with partial discs
pretending everything works the same, for three quarters an earth gravity the planets mass is about .03 moons
and the suns mass is... about a hundred earths
a one-day orbit for the pocket universe star is 200,000 km out, and from there the star is about 2.8 degrees in size which is about 9 moons
i think the furthest things can stay in orbit is when its period is 130 years
for each color: mass, rough analogue mass, rough size, furthest orbit
stars get larger despite that seeming contradictory because it also can't get too hot- but the bigger you are the quicker you cool
at 26,000 km (one-day orbit) around a pink/maroon star it takes up 2.2 degrees, at one-day around a turquoise it takes up four and a half (i'm beginning to become skeptical of this calculator because i have no idea what i did wrong), arond a spring green it's 7, at a gold it's 13... at a brick it's fifty-three because you're skimming the damn thing
so i think we will go with "habitability/insolation comes right from star apparent size"
so because of the weird temperature settings of this pocket universe, uninhabitability is generally uncommon- you can find someone for pretty much every place, even in young stars. but frankly most people are gonna end up interested in rocky worlds, because hey people are like that it's fine
so for those, the normal size range is between about 60 km (little planetoids) to a whopping 600 km (these are usually uncertain between gas planet and solid planet, some even are layers of solid above gas). so that's between about the size of estonia and about the size of the european union. an "earth" might be 100 to 200 km, so about between spain and mississippi. which is defintely for a good amount of variation lol
shellworlds and floating island worlds can be naturally formed even without a gas gint but they're kinda rare- the most common form is a semi-normal sphere-shaped planet with an equatorial ring of islands
gas giants range in size between 300 (very rare) and 2000 km in size
so the largest gas planets CAN exceed the size of their star, but they're usually in a binary orbit so it's even odds that gas planet will ignite
and the balance between a star and its system is a lot closer than in mundis mundis, often about 80 percent masswise for a star analogous to our own
pretending our solar system works-
so together thats still about 97 percent, so native systems will often bias towards larger planets.
....i wonder how space engines even work. of course aethersailing works, but really im talking about rocket-equivalents- less so interstellar stuff.
the issue with fucking with physics: not thinking through all the consequences. is combustion even a thing??
the rough band for a turquoise star for planets or asteroids is between about 8200 km (star-skimming, barely an option for large asteroids let alone planets, the star is 52 degrees wide and so the temperature is very similar to that of the star itself) and .8 au/120 million km (planets, stars, anything really, the star is .0038 degrees wide which is about the minimum size of saturn.
here's a hypothetical solar system, where all planets are of identical mass and size (200 km) and each orbit is exactly double the last:
stars outside of clusters are often about 30 au apart- a distance crossable by even simple technology in years rather than decades. galaxies are most often spiral, ring, or shells-upon-shells shaped, and are about 2000 au across (there are tens of thousands of stars per galaxy, an absolutely ridiculous number). galaxies are most often about a third of a light-year apart, though there are some vast voids in space over a light-year across. lightspeed travel is possible and fairly easy to achieve relying on the aether, though in practice standard speeds are often around a tenth of lightspeed for a galaxy-crossing time of about a third of a year and an inter-star transit time of about 2 weeks.