Artificial Star System

It's pretty far-out, but I don't think it's quite on the level of FTL.

One thought: neutronium. If you gave your planets neutronium cores, then they could conceivably have Earth-like gravity even if they were the size of asteroids. The problem is that the relatively small amount of neutronium involved might not be stable. It needs to be kept under a lot of pressure, and the only known way to achieve that pressure is to have a very massive amount of the stuff, which will then get compressed under its own gravity.

I don't know exactly how much neutronium you'd need to achieve stability, and I doubt anyone else knows either. So maybe you could just posit that it works. Or maybe you could handwave some way of "treating" the neutronium to make it more stable.

Maybe you could give the star its own neutronium core as well. Then it could have a more ordinary stellar layer surrounding the core, in which nuclear fusion could occur. Such a bizarre star probably wouldn't be able to last billions of years like our Sun; I'm not sure if that would be a requirement for your story.

To avoid tidal locking, orbital distances probably couldn't be quite proportional to the ones in our Solar System. I.e., maybe the planet could have a radius 1% of Earth's radius, and the star could have a radius 1% of the Sun's radius. But the star-planet distance would have to be considerably greater than 1% of the Sun-Earth distance.

I think you're going to run into a longevity problem.

Stars get going thanks to heat and gravity. That you'll have.

But a star that'll last needs billions of tons of hydrogen to have fuel for the fusion process over time.

Now, I am talking on an astronomic scale here. So your 1% star still might last several million years.

Rossing said:

I want the planets to orbit happily, not be tide (tidal?) locked. At least one has a breathable atmosphere. Sort of like superdense-asteroids (to achieve 1 g) in orbit around a tiny-sun. Basically, an entire, artificial, miniaturized Solar System. As small as theoretically-possible, actually.

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Your 1G asteroid will not be the same as a 1G Earth. Have a look here for a good explanation of what it might be like.

Rossing said:

If you see a book with 'neutronium-114', Kevin, you'll know it's thanks to you. (And you well may ...)

And yeah, I'm happy with a mere few million years. I'm a short-term thinker!

That's a great link, JimmyB27, thanks. I'm thinking more of asteroids about the size of Europa (https://en.wikipedia.org/wiki/52_Europa: picked randomly, because I'm punctilious like that). So not, I think, small enough (given the equivalent density) that you could jog into orbit.

I think. I don't know. Why is science so science-y?

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Jog into orbit? No, I don't think so either.
But you might find that there are still some effects on something like a rocket launch, for example?

Some other treatments of this theme discussed here: http://www.sf-encyclopedia.com/entry/great_and_small

The thing is, gravity isn't necessarily scalable on the astronomical level. Small, superdense objects behave differently from larger, Earth-dense objects. For instance, neutronium collapses any nearby normal matter into more neutronium - so you would need to find some way to keep the outer crust normal.

Rossing said:

Or is this a technological breakthrough on the level of FTL--so I'll just have to handwave it away?

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Frankly, pretty much, yeah.

caw

This is a fairly bananas idea, to the point that the most sensible literary device to explain it is just to invent the kind of way-out technology it would need; gravity manipulation primarily. As others have said there's no real way to make this work with current understanding. Also a star 1% the size of the Sun is going to give you a completely different light and energy output, and being so much closer to it would have consequences in terms of radiation levels, solar wind and so on, if the star is even heavy enough for nuclear fusion in the first place.

So yeah, it's really either go with mental technologies to bypass physics, or be physically accurate and have a much more normal-sized artificial star system.

It just occurred to me: angular momentum. I think that's conserved, and can therefore affect what happens if all this small stuff was formed by compressing larger objects.

So an object that yields earth-gravity and an earth-length day at earth size, will spin much more rapidly as it gets compressed. You can apply force to slow it down again, but then momentum becomes an issue yet again. Since you have a smaller "arm" to use in slowing the rotation, you have to apply that much more energy, or apply less energy for a lot longer.