Talk:Brown dwarf

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Would it be possible to create a brown dwarf - eg using a gas giant as a rubbish dump. (it would take a long time but 'Interstellar Route 593 Service Station 18972, dump your waste at the edge of spaceship park XXX in the general direction of the gas giant...' might be very busy.) Or, more likely, stars with high solar winds/binary stars with a gas flow between them and the gas giant is in a position to acquire more matter. (talk) 16:50, 8 February 2017 (UTC)

Theoretically possible, but you would need about 75 Jupiter masses (24000 earth masses) to create a brown dwarf und if you'd dump more than a few ppm in heavier elements than hydrogen or helium into the planet, the core would probably be made out of materials which cannot fuse in a brown dwarf --Imaginative username (talk) 17:04, 8 February 2017 (UTC)
The easiest answer is "not with existing technologies you can't". ikanreed You probably didn't deserve that 17:09, 8 February 2017 (UTC)
The gas giant rubbish bin would be a useful SF plot device - and the story-example is 'very far future at the present time': and others can be devised. And the second possibility (perhaps also a rogue gas giant planet [1] going through a gas cloud/stellar nursery)? (talk) 17:32, 8 February 2017 (UTC)
These advanced ships would probably be mostly self-contained environments where biological waste is reprocessed and turned into useful stuff or at least fertilizer again, while most nonbiological waste would be molten down and reprocessed as well. Major waste sources of materials which cannot be reprocessed would mostly come from the reactor. Reasonable power sources for interstellar travel are:
Nuclear fission: Produces radioactive waste you don't want on your ship, but that's mostly metals. If you want to create an object which mainly consists of radioactive metals, you wouldn't get a brown dwarf. It would probably glow for a while due to the heat generated by nuclear decay (and likely kill anyone trying to get near enough to dump waste) but it wouldn't be a brown dwarf, but a large ball of radioactive material.
Nuclear fusion: Produces harmless helium (and some slightly radioactive reactor elements which may require replacement after a while). An object mostly made out of helium wouldn't initiate nuclear fusion itself until it reached a mass dozens of times as large as that of the sun, at which point it would initiate helium fusion, a process which would render it similar to supermassive stars approaching the end of their lifespan.
It should be noted that both processes also produce neutrons and neutrinos. Neutrinos just fly through everything without doing much and cannot be collected in one place unless you're using a black hole. Neutrons themselves decay into protons and neutrons, but they can't be collected particularly well either.
Antimatter technology: Doesn't leave any waste products behind.
Again, you would need mostly light elements. Brown dwarves fuse deuterium into helium, and if you dump too many heavy elements (heavier than helium... but not almost 100% helium either, see the paragraph about nuclear fusion) into the gas giant, they would replace the core (heavy stuff drops into the center) and the deuterium wouldn't have a place to fuse. The only materials you could dump into the gas giant at will while still hoping to get a brown dwarf out of it at the end are garden-variety hydrogen and deuterium, and that's not a waste product on ships which use fusion or antimatter and isn't produced on fission powered ships. You're welcome to invent a power source which produces hydrogen and deuterium as a final product (you'll probably have to leave the realm of somewhat realistic physics here), but it's very unlikely that it wouldn't be used in the auxiliary fusion reactors which power the holodeck. The only sensible possibilities to artificially create a brown dwarf is by a concerted effort to condense an interstellar nebula (which is pretty much the process by which stars are created to begin with, so why stop with a petty half-star thing like a brown dwarf?) or to collide dozens of high mass gas giants (which is a pretty strenuous process, we're talking about ~75 Jupiter masses or ~24000 Earth masses here).--Imaginative username (talk) 18:38, 8 February 2017 (UTC)
Exploring the possibilities' - and for most 'persons not being astrophysicists/involved in the technologies herein discussed' what can be done with gas giants (apart from spaceships 'doing a Shoemaker-Levy 9 with anything non-recyclable') is a bit vague. (And there would be a 'keep-gas-giants-unpolluted/don't fly-tip gas-giants into black holes' (which would probably take a #very# long time)movement should spaceship development reach the stage where this discussion becomes meaningful).

Would the natural processes suggested 'work'? (talk) 19:08, 8 February 2017 (UTC)

A rogue planet which is already close to being a brown dwarf crashing into another rather large proto gas giant would be a possibility, albeit pretty unlikely. If you're talking about a mere jupiter sized rogue planet, I doubt there's any possibility of it gathering enough matter to turn into a brown dwarf without encountering an almost brown dwarf sized gas giant/protoplanet there... and in the latter case, the jupiter sized planet would be destroyed altogether and mostly absorbed by the larger planet.
I'm not an expert in solar system physics, but if I remember my astrophysics introduction, rogue planets are considered to be planets which were slinghotted out of a star system and didn't form on their own. Given how gravitational slingshots work, the rogue planet shouldn't have been the most massive planet in its former system. This makes a ~70 Jupiter mass rogue planet rather unlikely (since it would probably the heaviest planet), but not impossible. It could have originated in a binary star system (which is unlikely, however, slingshots require similar orbits and I don't think that an almost star sized object could survive that close to the orbit of an actual star), or, what is more likely, could have been slinghotted out when a compact object like a white dwarf, neutron star or black hole entered a system.
This is my background story for the plot you're thinking about: An advanced civilization manages to redirect a black hole through a star system with a 70 jupiter mass gas giant. That isn't too far fetched: If the black hole is sufficiently far away, it only requires a small change in velocity to significantly alter its position a couple centuries later. It could be done by a simple gravity tractor, i.e. a very large ship flying close to the black hole for some time and imparting a momentum change onto the BH due to its own gravitational pull. With sufficiently powerful computers, the species can compute the orbit of the black hole well enough to cause the gas giant to be slingshotted out of the system. The other orbits in the system would shift as well, albeit less dramatically, which would give rise to a revenge story or religion if there's a sapient species in that system. The gas giant then flies towards a stellar nursery (requires even more precise computation at the beginning). Its trajectory can, again, be altered by a gravity tractor s.t. it actually hits a sufficiently large gas giant in the nursery and forms a brown dwarf. --Imaginative username (talk) 19:49, 8 February 2017 (UTC)
Thanks - 'mainly curious.' So probably 'occasional and various uses when practical interstellar travel develops', along with a few 'peculiar experiments and other activities', and 'several bizarre conspiracies and woo-theories' (as well as the occasional TV-equivalent series: Steptoe and Son perhaps?) - and passing mentions in SF for now. (talk) 15:21, 10 February 2017 (UTC)

And would this (SF) planet [2] be actually viable? (The backstory is not.) (talk) 17:29, 13 February 2017 (UTC)