Drawn by me, I hope it's ok...


"...Regino is a gas giant approximately the size of Saturn, and three moons, Reo, Gei, and Tan orbit it. All three are small, rocky bodies a half to a quarter the size of Earth's moon. Aside from mining, the planet and its moons are not part of any significant project within the system...until now.

Ouranos, the 1.1 solar mass, main sequence yellow dwarf star Aetheria orbits, is becoming host to a currently in-progress dyson swarm and dyson sphere. When this is completed, in order to maintain the habitability of Aetheria, Regino and it's three moons will be fused and ignited to create an artificial star, designed to provide light and warmth to Aetheria and it's two moons. ..."

The question is, is this scenario possible, and if so, how could it be accomplished?

Assume the following-

  • A material exists that can withstand the stress involved with a solid dyson sphere(possible actually, contrary to popular belief).
  • This civilization is approximately 2.2-2.3 on the Kardashev scale.
  • This civilization does not possess FTL technology or time travel technology-basically no clarketech, or technology that is deemed impossible by our current understanding of physics(rather redundant for this scenario, but whatever).
  • Ouranos' dyson sphere will almost entirely cover the star, with essentially no surface area exposed unless starlifting is in progress or the stellaser is activated(if you are unfamilar with these terms, google em). Remaining energy leaking out? Well... that's what the swarm's for.

If you need to know, the swarm is about 0.1 AU from the star, sphere is around 0.01 AU.

Regino orbits 3.5 AU from Ouranos. Aetheria orbits 1.1 AU away.

Thank you and I hope my question is up to par.

Note: Bolded text in the scenario is the relevant information.

  • 2
    $\begingroup$ So much of the content here is utterly irrelevant to the core question. It makes it really hard to know what is the question. $\endgroup$ Commented Jan 12, 2022 at 21:53
  • $\begingroup$ Alright, then ill only leave the important parts. $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 21:54
  • $\begingroup$ @GaultDrakkor better? $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 21:56
  • $\begingroup$ Is the core question: can the gas giant Regino be ignited into a star? $\endgroup$ Commented Jan 12, 2022 at 21:58
  • $\begingroup$ Yeah. Essentially. $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 21:59

3 Answers 3


Can the Saturn like planet be fused with its three moons to make a star? Short answer: Nope

Saturn has a mass of approximately 5x10^26 kg Sun has a mass of approximately 2x10^30 kg (A 1 solar mass (SM))

To kickstart a nuclear fusion by gravity alone, you require somewhere between 0.05-0.1 SM (reference: https://hypertextbook.com/facts/2001/KellyMaurelus.shtml )

Whereas Saturn has around 0.00025 SM. Ie. You would need to fuse approximately 200 Reginos worth of mass to start a fusion reaction.

I am afraid, that in order to keep the planet habitable you would need to keep a “window” in the dyson swarm to leave the the light in the direction of the planet unobstructed. Or use the energy output of the sun to keep the planet habitable (stellasers?)

  • $\begingroup$ hmmm would it be possible to sustain a mini star using a constant supply of matter/energy? $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 22:41
  • $\begingroup$ @Sync it has to be a LOT matter/energy (much more than Regino actually has) to sustain natural thermonuclear process. However, a civilization which is 2.2-2.3 on the Kardashev scale might possess some kind of "catalyst" to keep thermonuclear process going under not so extreme conditions. $\endgroup$
    – Alexander
    Commented Jan 12, 2022 at 22:48
  • $\begingroup$ @Alexander So like a stellar rejuvenator in place orbiting Regino? Constantly supplying energy and hydrogen to maintain the fusion reaction? $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 22:52
  • $\begingroup$ @Sync I have been thinking about it for past 20 minutes and cannot come up with a sensible solution. You can safely extract 0.1 SM from your main star and use that to ignate Regio, but this will likely destabilize the orbit of other planets, and slingshot them out of your star system. $\endgroup$
    – Dvorkam
    Commented Jan 12, 2022 at 22:59
  • 1
    $\begingroup$ @Sync You could expend energy to initiate Regio’s fusion artificially, but it would cost more energy then you get out of it. Probably the most “viable” solution would be to extract 10-15% of SM and use that mass alone to form a smaller star and change your system to binary star system. The wobble just might be small enough to keep your planet in the Goldilock zone $\endgroup$
    – Dvorkam
    Commented Jan 12, 2022 at 23:06

Igniting Regino is remotely possible - or at least can be handwaved. You could initiate a core collapse in the planet, replacing a large enough part of its rocky core with stabilized degenerate matter (you don't have the pressure to have matter undergo electron degeneracy by gravitational pressure alone, but once it's achieved somehow, the density of the degenerate core can stabilize the process: it's how micro black holes are thought to have been born). The subsequent implosion of the planet, plus the pressure, would - wiggles hands magically - do the rest.

Or you could surround Regino with muon projecting statites. Muons are particles akin to electrons, but 200 times more massive; muonic deuterium experiences a reduced Coulomb barrier and can undergo fusion spontaneously.

The problem now is that you have an ignited gas giant on an orbit that's probably on the order of 30-40 years, and a distance from Aetheria that varies between 1.3 and 2.0 billion kilometers, while Aetheria's distance from the Sun was probably a fifth of that.

In other words, even if Regino could produce the same flux and spectrum of Aetheris's sun, Aetheria would get one twenty-fifth of the original flux.

The two solutions (one better, one bad) I can see are:

  • leave a large enough opening near the North pole of the Dyson sphere, about 4-10 times as large as Aetheria's cross-section. Park a mirror statite there, which will focus a "sun ray" from way above the star towards Aetheria. Light pressure from this ray and other balancing rays shot towards the empty space will keep the satellite at the desired distance, counteracting the sun's gravity.

  • build massive sun-spectrum lasers on Regino, use its hydrogen to fuel a Sun lamp aimed at Aetheria and exactly collimated, so that by slightly adjusting the output you can ensure the correct irradiance at all points in Aetheria's orbit. If both Aetheria and Regino are exactly on the eclyptic, you're in for a world of hurt, because for about half a year Aetheria will be on the other side of the Dyson sphere from Regino, unreachable by the laser and therefore in complete darkness.

  • $\begingroup$ It wouldn't be hard to adjust Regino to have it being orbited by Aetheria, and that system orbiting Ouranos $\endgroup$
    – Sync
    Commented Jan 12, 2022 at 23:49

Stellification seeding a black hole into the planet


"If the density of the star or planet could be increased, fusion could be initiated. One such method is to "seed" the body with a black hole. Although the black hole would initially start swallowing the body, the huge output of radiation caused by this would resist the flow of further material"

The mini black hole (a grain, actually) would remain inside.. very slowly collapsing the planet.. in the process, the kernel pressure gets large enough to ignite it. In the article it sais 10e+21 kg could warm up a planet considerably, that is 1/8 moon mass, in exotic matter, or black hole matter. A gas giant may ignite into a brown dwarf.


Read about the internals of really big planets,



You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .