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Long ago, in some distant galaxy, an advanced civilization had turned a small, young elliptical galaxy into their own astronomical playground. They seemed to have come up with a way to prolong stellar lifespans. For further clarification, they could theoretically prolong the lifespan of a blue supergiant (20 times wider than our sun, 20-1,000 times as massive and 1,000-one million times as bright) from ten million years to ten billion, a yellow hypergiant (1300 times wider than our sun and 500k-750k times as bright) from a few million years to a few billion, and a red hypergiant, which has a natural lifespan of 100,000 years, can live as long as a red dwarf.

Through artificial, technological means, how would this advanced alien race prolong these giants, supergiants and hypergiants far beyond their natural limits?

JohnWDailey
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    The civilization is undefined. The future is undefined. The technology is undefined. How can this question possibly be answered? Since the technobabble tag was completely shot down, I had to VTC:OB. Even if we open this up to wild flights of fancy, how will you judge a best answer (which is how to avoid closure as opinion-based)? – JBH Apr 17 '21 at 21:48
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    You could always just handwave it by stating that the star now achieved a higher proportion of mass-energy conversion than the 1%. It doesn't actually break the laws of physics and is suitably vague enough to be considered plausible. – Broken ECLSS unit Apr 17 '21 at 22:22
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    Quick comment on mass - a supergiant won't reach $\sim1000M_{\odot}$; the cutoff for stars is roughly an order of magnitude below that. By the way, related questions, albeit targeted at less massive stars: https://worldbuilding.stackexchange.com/q/134250/627, https://worldbuilding.stackexchange.com/q/192618/627 – HDE 226868 Apr 17 '21 at 23:11
  • I want to leave it open on the basis of science-fiction as a tag, which is what it is, but the lack of constraints for a best answer rears it's ugly head as JBH sais. If you can give us more to narrow it down, then you should be ok. – Escaped dental patient. Apr 17 '21 at 23:52
  • @ARogueAnt. Narrow it how? – JohnWDailey Apr 18 '21 at 00:19
  • Specify: technology available perhaps, maybe you can constrain to speculative possibilities of tech which is already hypothesized. It's a tough one, asking for technobabble is obviously off-topic, yet science-fiction tends towards that. Would it be acceptable to feed the star continually with stellar remnants and interstellar gas to sustain it? Would a Vacuum energy stellar-core fit? Has your civilisation discovered how to get fusion from heavy elements, a wormhole to an anti-matter universe? We need to know the tech your civilisation might have in order to figure out how to explain it. – Escaped dental patient. Apr 18 '21 at 00:31
  • @ARogueAnt. I don't know all these things. That's why I asked in the first place. – JohnWDailey Apr 18 '21 at 01:04
  • Not sure I do either. Still feeling my way here on the network. I've given you my best suggestions here though, and there are many close votes. That being said, maybe the answer you needed is already written below. But the ethos here seems to be not just to help the OP with their single query, but to provide a repository of authoritative knowledge, such a thing requires questions and answers to be as well defined as possible. Even if you have what you need, you can still [edit] to make the question fit better with that. Best of luck. – Escaped dental patient. Apr 18 '21 at 01:16
  • The lack of detail and specifics allows for an answer such as "simply convert the red hypergiant into a red dwarf', and there is no criteria to judge the answer. – Justin Thyme the Second Apr 18 '21 at 01:56
  • at 1000 solar masses, would it not instantaneously collapse into a black hole? – PcMan Apr 19 '21 at 07:23
  • @PcMan No, it would be a blue hypergiant. – JohnWDailey Apr 19 '21 at 09:53
  • @JohnWDailey no, blue hypergiants range from 120 to about 270 times the mass of the sun. Larger than that, and their luminosity exceeds the Eddington limit, and they shine themselves apart. And at something like 800 solar masses (but the math is very hard), it will simply form a black hole and collapse into itself.. The heaviest star known is BAT99-98, at 226 sol masses. And yes, it is very much shining itself apart, with huge mass loss from the surface due to luminosity. – PcMan Apr 19 '21 at 10:05

2 Answers2

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Technobabale mass energy conversion

Stars usually use fusion, which has a mass-energy conversion ratio of about 1%. If you want to have your stars live longer you could always just wave your hands and say that they achieved 10% or 100% mass-energy conversion, which would extend their life spans to a degree, maybe not by a factor of 100 but they would exist for a longer time period, eg 100 million years blue giant to 1 billion years, or yada yada.

Potential handwaves are

  • Antimatter produced in nuclear reaction to achieve a higher mas energy conversion rate
  • Blackhole stars- eg hawkings knots
  • More efficient fusion
  • Cutting out some "waste" product of the stars that's not necessary
  • Exotic particle physics
  • High-density particle physics
  • Violation of symmetries which result in conservation of energy
  • Magic
  • Etc
Broken ECLSS unit
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  • You have a good list, but one that also raises some new questions. 1) How do Hawking's knots really work? Google doesn't have much info on such. 2) What do you mean by "exotic" or "high-density particle physics"? 3) Similarly, what does "violation of symmetries" mean? – JohnWDailey Apr 18 '21 at 00:05
  • @JohnWDailey 1) Hawking's knots, in most forms work by, to simplify dramatically harvest the Hawking radiation of black holes(Hawking radiation its self being a bit more complicated than portrayed to the public), while feeding them mass, allowing for potentially near 100% mass-energy conversion, creating "stars" which if used properly could use anything as fuel, including a star providing the mass flow inwards and the energy radiated outwards are at a stable ratio so the amount of Hawking radiation radiation and the mass of the black hole is constant. – Broken ECLSS unit Apr 18 '21 at 01:23
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Some stars fade out because they run out of fuel; not much that can be done about that.

However, other stars explode because of core collapse before burning all of their fuel: supernovas. The elements at the core of the star have fused to iron which cannot be further fused to release energy to sustain core's pressure against the weight of the outer layers of the star, causing it to implode and then supernova. The solution is "obvious"; a gargantuan tubular force field created through (technobabble goes here) is driven into the heart of the star to vent out the useless iron, extending the life of the star until all fuel is burned. The vented iron (quintillions of tons of it) is either allowed to escape the star's gravity into interstellar space or collected using (technobabble goes here) for some purpose (Dyson sphere or somesuch).

This works for other star types as well; e.g. a red giant forms because it isn't massive enough to trigger fusion of the carbon / oxygen at its core. This "dead" core material can be extracted and vented or even launched using (technobabble goes here) to a larger star that is massive enough to burn it.

GrumpyYoungMan
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  • "The elements at the core of the star have fused to iron which cannot be further fused" Within the almost nil constraints of the question, this could be hadwaved away through technobabble to allow iron to fuse further, thus allowing the star to 'burn put' rather than im/explode. – Justin Thyme the Second Apr 18 '21 at 16:24