How big can a star system be?

Very.

A couple of light years away if you count the Oort cloud (0.8 and 3.2 ly). The habitable zone on bigger star would probably be that far away.

Can Neutron Stars or even Black Holes have habitable zones?

>>50118157
Somehow I doubt it. Severely.

>>50118157

Probably not. Neutron stars and black holes can have planets. They are either captured planets or "phoenix" planets rich in heavy materials formed after the supernova.

However, a binary system can contain a star and a black hole/neutron star. The big sisters would have died within a million years, while the smaller sun would continue to exist for billions of years. Depending on the proximity the Black Hole/Neutron Star may absorb material from the surviving sun.

Neutron stars are the most radioactive thing in the universe and are unlikely to have any life close to it. Black holes are safer so long you don't count the accretion disk.

>>50118157

It would be a system rich in heavy and rare materials but poor in any lighter element like hidrogen (so no water). Great for resource extraction with some ultra-fancy technologies, but not a good please to live.

>>50118157
Black holes couldn't have life zones unless they're part of a binary, trinary, or more system with one or more living stars. Because, you know, they don't radiate heat or light, as kind of a defining characteristic of a black hole. And heat and light are somewhat necessary to life as we know it.

>>50118157
Well, Black Holes don't actually give off any light, do they (unless you count x-rays)? Kinda known for it.

>>50118116
Hypothetically, you could have a system with five or more stars or a supermassive star over a billion miles in diameter, but neither of those would likely be especially liveable.

>>50118116

So long the combined mass of all the planets is less than the star.

>>50118621
Why? < No idea of science.

>>50118686
Lots of wonky radiation bullshit.

Also, having multiple stars often leads to random shit (possibly planets, etc.) colliding with stars.
Also also, the bigger a star is the shorter its lifespan. So big star -> short window for life to develop.

File: vy canis majoris size.png (371KB, 1565x978px) Image search: [Google]

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>>50118116
Well, the biggest star we know of is VY Canis Majoris, which is pic related in size, so uh

Go wild, I guess

>>50118686

Bigger stars have very short lives. About a couple of million years. The bigger a star is, the shorter their lifetime. This is too the point that not a single red dwarf star have ever died, the universe is not old enough.

Also, the biggest ones are often unstable (every star is a fight between gravity and the forces going outwards).

>>50118686
More stars = more radiation = baked planets. Thanks to light coming from multiple angles, planets in binary or more systems can have far shorter night periods, which means less of the planet's surface area is radiating heat into space at any given moment without being overwhelmed by incoming energy. Basically shit never has a chance to cool off.

A hypothetical 5-star system would also have some absolutely bonkers gravitational pulls going on, leading to terrifying crazy-straw orbit paths and irregular orbital velocities, neither of which is conductive to habitable planet formation. The stars would probably be ripping eachother apart as well, further complicating the situation with colossal plumes of plasma.

I doubt anything larger than a minivan could last longer than a decade in such an environment before gravity tore it to bits, flings it out of the system entirely, or it got vaporized by a close pass.

>>50118794
>VY Canis Majoris
biggest is uy scuti m8

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>>50118686
If, for instance, there were 5 stars.
https://en.wikipedia.org/wiki/Circumstellar_habitable_zone
This aspect is extremely complicated and I don't really want to explain it. Basically, a large number of stars would create an environment that is /too/ unstable for a life-sustaining planet to form. The intrinsic conditions of such a system would probably also be too extreme, such as the distribution of mass and the ages of stars.

If there were a massive star it would die very quickly (in cosmological terms), within a few million years. The rate of fusion within its core would be much higher than a star with less mass simply because there is much more pressure. Higher pressure means higher temperature, which means individual atoms have greater kinetic energy, which means they are moving faster and colliding more frequently, which means they are more likely to fuse.
Each fusion reaction converts some energy into binding energy, and releases some amount of energy as radiation products.

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>>50118877

Red Dwarf.

>>50118864
Oops, you're right! My information is outdated.

>>50118813
And now I want to run a space opera session where a major challenge is navigating through a five-star system that is an eternal shitstorm.

>>50118116
A star system is any group of stars that are gravitationally bound to one another.

Size is not part of that definition; so long as the constituent stars remain gravitationally bound there is no upper limit on how large a star system can be.

>>50119335
Gravity propagates infinitely; by that definition the universe is a single star system.
Which is technically accurate, since it's a system comprised largely of stars, but that's not what "star system" generally is used to mean.

A star system is generally defined as the objects influenced significantly by a (generally singular) star.

>>50119401
>A star system is generally defined as the objects influenced significantly by a (generally singular) star.
By that definition, galaxies are star systems, because they are influenced significantly by a (former) star, AKA a supermassive black hole.

>>50118877
Holy shit.
I wonder how the sky would look on such a planet.

>>50118877
Yeah, the problem is that O-type stars die super quickly, though. There isn't much time for the planets to cool down and even less for an ecosystem to arise.

>>50118794
biggest isn't relevant, what is relevant to start system size is mass

and as >>50118877 pointed out that title currently belongs to R136a1 with its 300+ solar masses
Largest estimates for VY canis majoris are around 25 solar masses

R136a1 is ungodly insane, check it out https://en.wikipedia.org/wiki/R136a1

>>50119556
>former
And there's the key word.

Further, most galaxies don't have a black hole at their core, and a definition that narrows "the universe" down to "a galaxy" is still an improvement.

>>50119612

Ultraviolet radiation everywhere. You wouldn't see much because your eyes are damaged by that. Get ready to get sunglasses and lots of solar cream. The planet can have the right temperature, but these UV will fuck your skin.

Neverending aurora over the entire planet visible even in daytime as far as the equator. Century-long seasons...


>>50119615

It could be a planet unlucky enough to get captured. Nothing will evolve quickly enough for complex life, but you may terraform it.

>>50118116
Short answer; we have absolutely no idea and every time we do we discover a new special case.

>>50119556
IIRC galactic singularies are not stellar remnants and instead formed directly from the collapse of huge gas clouds

>>50119612

The star will be so far away that it will be of the size of any other star on the sky. And yet, all light would come from it.

>>50118116
Not as big MUH DICK

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>>50119612
~750AU away, surface temp on the giant's satellites is over 120°C. The one in the bottom right is Earth-sized and massed.

>>50119786

I think that the most likely origin is primordial Black Holes formed before the inflation.

>>50119751
would be no point to it: O types, especially the ultramassive ones, are incredibly unstable and its energy output would change notably over as short a period as a human lifespan
heck R136a1 is younger than most hominids and is already halfway through its lifespan

on top of it they're extremely rare

there's absolutely no reason we'd bother terraforming anything around one of them when there's so many friendly G and K classes around

>>50119888

B - type at least could hold thousands of objects with hundreds of planets that could be terraformed on the local "Kupier Belt".

>>50119932
B-'s are fairly unstable as well, not to mention rare and tend to hang around close to other B-'s which is not a place you want to be hanging out if your species is vulnerable to the effects of close range supernovas

seriously why bother with all the exotics when there's millions of k-class stars around, most of which will have planets

>>50118621
>Hypothetically, you could have a system with five or more stars
I've seen the math for this, while technically possible, I thought it was incredibly implausible and would almost certainly be completely inhabitable.

>>50119401
No, anon, you're thinking of a *planetary* system.

https://en.wikipedia.org/wiki/Star_system

And while you're correct that gravitational attraction propagates to infinity, it is not correct to say that all objects in the universe are gravitationally bound to one another. There's this thing you may have heard of called "the expansion of the universe"; if all objects in the universe were gravitationally bound to each other that wouldn't be a thing.

Note the difference between the terms "gravitational attraction", and "gravitationally bound". The moon is gravitationally bound to the Earth and the Sun; it orbits both. The Voyager space probe is gravitationally attracted to the Sun, but is not bound; it trajectory is hyperbolic and carries it away.

tl;dr learn some fucking astronomy before you go shooting your mouth off again.

>>50120033

A B system with so many worlds, could be a huge economic federation, a true superpower of the future. The life of the star would be very short in astronomical terms, but no civilisation on Earth have lasted more than a few thousand years.

But yeah, for long-term planning, the best bet are the smaller stars.

>>50120054
depends
if its two double star systems orbiting around a central point of gravity with a 5th star orbiting around the entire system that 5th star could have stable planets

>>50120113
problem is though the A's and especially B's have significantly larger UV range emissions compared to G's and K's (technically M classes would have even lower but they have other issues) which in turn would require all kinds of specialized equipment just to keep the objects livable

not to mention a multi-moon gas giant in a star's habitable zone would have a significant amount of worlds as well for the economic federation situation, and while that scenario is rare, A's and B's themselves are also quite rare to begin with

>>50118921

A note about this one Barnard's Star is older then our galaxy. It still kicking and won't die any time soon. The universe is too young to see even the oldest ones kick the bucket.

>>50120214
>Barnard's Star is older then our galax

https://en.wikipedia.org/wiki/Barnard%27s_Star

>At 7–12 billion years of age, Barnard's Star is considerably older than the Sun, which is 4.5 billion years old, and it might be among the oldest stars in the Milky Way galaxy.

https://en.wikipedia.org/wiki/Milky_Way

>Globular clusters are among the oldest objects in the Milky Way, which thus set a lower limit on the age of the Milky Way. (...) Age estimates of the oldest of these clusters gives a best fit estimate of 12.6 billion years, and a 95% confidence upper limit of 16 billion years.

Do you fucking nerds even know how to look shit up?

>>50120277

There are even older stars. Some are near as old as the estimated age of the universe.

>>50120392
problem with old stars is they're all very low luminosity so we can't detect them at to great a distance

>>50120392
Okay, and?

Barnard's Star is still not "older than our galaxy".

>>50120277
>Globular clusters can be 16 billion years old.
>The universe is 13.7-13.9 billion years old.
Nigga, what the fuck are you doing?!

>>50118287
almost all a neutron stars radiation can be projected out in two narrow polar beams if its a pulsar. a hypothetical planet too "the side" of a neutran star orbiting a relitively distant binary companion could have low enough radiation for life to survive. likely still too high for most life on earth. But we do have bacteria that live inside nuclear reactors so it wouldn't be impossible for Earth-like life.

>>50120481
This is why Wikipedia is cancer.

>>50120481
thats the upper limit based on the physics of glubular clusters.

no one is saying that they're actually older than the universe.

How old could be the oldest possible civilisation given the age of the universe? It has to be from the second or third generation star, since there woulnd't be heavier elements than hidrogen and helium before the first ones came and go. So how old could it be?

>>50118561
Yes and no. What you actually need is energy, no matter the form. And both black holes and neutron stars dissipate plenty. Sure the conditions would be peculiar, to say the least, but in terms of thermodynamics you could technically have something multiplying off that energy which could be considered more or less as life, depending how broad your definition is.

>>50121302
plus the accretion disks surrounding black holes give off massive amounts of energy.

>>50120865
This anon has it. "It" apparently being reading comprehension.

>armchair astronomers ITT

>>50121302
Radiotrophic fungus growing in the chernobyl reactor uses meleanin too get energy from gamma radiation in a process that resembles photosynthesis.

>>50121245

If it took nearly 5 billion years for Earth to produce us, then the oldest one can't be more than 2-4 billion years older than us.

>>50121861
To produce us, yes. But that's only because there were loads of extinction events that kept setting back the clock.

So the earth is about 4.5 billion years old. "Life" in the sense of cellular organisms appeared between 3.9 - 3.7 billion years ago. It's an incredibly arrogant and anthropocentric position to say that "the earth took its entire life to produce us".

>>50121933
>So the earth is about 4.5 billion years old. "Life" in the sense of cellular organisms appeared between 3.9 - 3.7 billion years ago. It's an incredibly arrogant and anthropocentric position to say that "the earth took its entire life to produce us".
Though it is technically true. It did take THE EARTH it's entire life to produce US. But yeah, other planets could have attained human level intelligence in a much shorter time frame than ours took. Plus, even if another planet only took 1000yrs less time, with our rate of growth, that could put that species ahead of us by leaps and bounds.

>>50121861
our sun is relatively young though.

the first stars formed as early as 100 million years after the big bang and if super giants would have only lived for as little as a dozen million years.
it's reasonable to say there can already be second some generation stars with heavier element containing planets forming more than 13 billion years ago.
So following earths model you can have a civilization appear as far back as 8 billion years.

>>50122013
you could probably crank it up close too 10 billion if their planets life lucked out and made the jump from single to multicellular after 1.5 billion years instead of 3.5 like earth.

>>50121245
Without knowing what environmental factors led to hominids becoming capable of shitposting, and why literally nobody else out of perhaps 5 billion species in 4 billion years got to that point, it's hard to say how long it's "supposed" to take for intelligent life to show up. We need to know the trigger and the likelihood of it appearing in the lifetime of a star's habitable zone.

For all I know most intelligent life shows up at the extreme end of their planet's life, and the reason we can't find aliens is because they couldn't develop interstellar travel before the star stopped propping them up with free heat and shit. We could be the weirdos who only took 4 billion years to develop and had breathing space to escape.

I do wonder, if it is possible there were civilizations 8 billion years before us

then where the fuck are they

a very depressing answer to that question could be that no matter how much time an intelligent creature has, it can never go all that far beyond its own planet

>>50122131
also 8 billion years is a loooooooong time for a species to just hang around. They would likely have died off or evolved into something else in that amount of time

>>50122131
When even the most assbackwards of space-faring sapients can construct RKVs, it's not a good idea to broadcast your location.

>>50122183
>t. great filter

>>50122131
space is a big place, like infinite kind of big, they are probably way too far to get a broadcast not a billion or more years old