What kind of catastrophic phenomena could cause a solar system to be wiped out with little to no warning?

It's a pretty simple question: imagine you have a solar system about the same size as our current one. This solar system is close enough to nearby colonies that most observatories can see the planets in the system but not so close that they would be wiped out as well. I'd ballpark the distance to be about a light week or two, but that is a completely random and unscientific number, so any distance that would make the system visible but not dangerous to others is fine. There are also plenty of supply runs and probes and other forms of data entering and exiting the solar system.

And yet, with almost no warning, the solar system is destroyed. This could be in the form of an actual explosion, supernovas, antimatter, anything based on science.

The problem is, astronomers could easily see most space events ahead of time, events that usually take a long time to react.

So, what kind of scientific phenomena would wipe out an entire solar system with almost no warning?

• Bonus points if the system becomes dangerous/uninhabitable post-catastrophe
• Double bonus points if the system becomes unsalvageable post-catastrophe (no metals can be mined, the system has completely gone away)

Clarifications: Destroyed means the entire system is obliterated like the planets are rumble. The unsalvageable bonus part is if that rumble is basically only atoms or something that other colonies could not harvest for themselves.

• Kurtzgesagt likes blowing up everything and has a lot of potential candidates for such a thing, I'll link on on gamma ray bursts but vacuum decay or strange matter or black hole bombs if your civilization is advanced enough, are all great ways to wipe stuff out. youtu.be/RLykC1VN7NY Apr 9 '21 at 19:15
• I think the biggest problem is how to destroy a solar system without harming colonies only 1 light-week away. I mean, a supernova or something could take out a solar system but you wouldn't be safe right on the edge of it. Apr 9 '21 at 19:24
• "Destroyed" means all colonies are destroyed, or everything, including host star, ceases to exist? Apr 9 '21 at 21:08
• A light week is extremely close for a nearby star system, at least within a reasonable galactic habitable zone. Consider that the nearest star to our solar system is around 4 light years distant, and that Sedna's orbit around the Sun extends to 937 AU (5.4 light days) at aphelion. Apr 10 '21 at 11:26
• What's the internet coming to, questions been out almost a day and nobody has mentioned the Vogons! Apr 10 '21 at 12:10

Gamma Ray Burst

A nearby GRB manages to dead-center the solar system with one of its polar jets.
This jet of energy contains the energy output of a typical star's entire 10-billion-year lifespan, focused along two polar jets. The Jets are quite directional, as narrow as just 2 degrees wide. Each contains something like 10e44 Joule, enough to vaporize a planet several billion times over.

The planets in the system are literally vaporized. In addition , the star is overheated and busy trying the Red Giant fashion style.

• 2° is still too wide to be useful: It means that the source can only be 28 times as far away as the length of irradiated cross section's diameter. The closest stars are somewhere in the tens of lightyear range, so the GRB source would need to be closer than 2800 light years. That's still comparable to the thickness of the stellar disk (2000 light years). As such, the GRB source would need to a part of the milky way itself, and in close proximity of the to-be-destroyed solar system. And that means, scientists would know its progenitor since like forever, and have closely followed its evolution. Apr 10 '21 at 12:34
• They might know a near by star has the potential for a GRB, but not know the exact time. Since a GRB travels essentially at the speed of light, when it does happen it will be moving so fast that unless there is faster than light communication or detection no one would see it coming. Apr 10 '21 at 14:24
• That said, if the GRB is produced by the collision of two neutron stars that happens purely by chance (i.e. not as a result of a downspiral, the gravitational waves of that would make laser interferrometers hum like hell) would fit the bill: Two individual neutron stars without poles pointing in the right direction would be very hard to detect, and when they meet, they release their energy literally within milliseconds. Apr 10 '21 at 14:24
• @cmaster-reinstatemonica yep. ludicrously unlikely, but then the whole premise of a whole solar system being wrecked and nobody noticing is a bit of a stretch. Apr 10 '21 at 17:09

Star Lifting Gone Wrong

There are very few natural phenomena that are big enough to wipe out a solar system, but also small enough to not kill everyone just a few light weeks away. The only real candidate for this would probably be a nova (not to be confused with a supernova). Smaller novas can cause a star to flare up its energy output somewhere in the range of 8 orders of magnitude when they happen. If you were to imagine the Sun suddenly getting a few million times as bright as it is right now for a few days, you can easily imagine all planets in the solar getting scorched to a crisp, but a few light weeks out being fine. The problem with these is that it's very easy to detect a star cluster that is at risk for this type of event, and such stars tend to have nova at intervals too close together to even allow life to get much of a foot hold around them, and they are recognizable by having white dwarves at very close proximity to a main sequence or red giant star... so you'd never end up near one by accident.

But, perhaps your people did not evolve around this star, but colonized it specifically because it has a closely orbiting white dwarf/main sequence star pair. Their goal could be to try to interrupt the pattern of Novas while harnessing the matter stream between the white dwarf and main sequence star as a sort of star mining program. By harvesting this stream they could collect enough raw matter and hydrogen fuel to build and power massive Megastructures like Dyson Spheres and/or more star lifting platforms.

But something went wrong... The mega structure that is supposed to be held in gravitational equilibrium between the star and the dwarf drifts a little to far and starts to fall towards the dwarf. Because the stars are so close together, it is only a matter of days, maybe even hours before the station containing billions of billions of tons of stockpiled mass crashes down into the white dwarf and all that hydrogen atmosphere that it normally takes years building up is introduced all at once. The mass of the star lifting station triggers the nova event that the station was designed to prevent.

Because communications only travel at lightspeed, by the time the colonists get the message that the station is falling into the dwarf star, it will have already happened. All they can do is watch and wait for the inevitable flash of light. While this is not exactly instant, it's probably the closest you will get barring any sort of intentionally activated weapons of mass destruction.

When you get to the scale of "wiping out solar systems" there aren't many phenomena capable of producing power on the insane levels we're talking about.

The most likely option is to have a rogue black hole hurtle through the system and rip it apart.

Detecting a rogue black hole might be incredibly difficult, as the only thing you can see is the distortion as it passes in front of background stars.

The tech level require for inter-stellar colonies almost surely allows for constant monitoring of every visible star, but with a bit of "luck" a rogue black hole could slip by until it was too late to do anything.

What exactly would happen to a solar system that collides with a rogue black hole depends on a large number of factors. Planetary and stellar bodies rarely collide directly though.

So to have the planets of this solar system "completely gone", the best bet would be for them to be ejected VERY violently from the solar system by the gravity of the passing black hole.

You could also have the planets redirected into the star or black hole which would surely destroy them but is probably less likely than simple ejecting.

• What would make a rogue black hole "hurtle"? And what size would it need to be to destroy a solar system "about the same size as our current one"?
– Len
Apr 9 '21 at 20:16
• @Len The same thing that would make a sun hurtle. Perhaps a galactic merger. Though large enough to destroy a solar system is pretty friggin' big, larger than many supermassive black holes and hurtling such a thing might require something even bigger to interact with during the galactic merging. Apr 9 '21 at 20:33
• A supermassive black hole would be more effective at utterly annihilating a solar system, but a galactic merger hardly sounds like an event that would go unnoticed to an inter-stellar civilization lol. Normal intragalactic chaos should produce plenty of stellar black holes zipping around hazardously. Apr 9 '21 at 20:53
• @Len You don't need stellar interactions on the scale of galaxies nor supermassive black holes to have massive orbital perturbations. All that constitutes a "rogue" black hole is an orbit that isn't following the "normal" galactic orbit. Near misses with other black holes or massive stars could easily eject the black hole and put it on a collision course with an unaware solar system. NASA estimates 10Million - 1 Billion black holes in our galaxy - science.nasa.gov/astrophysics/focus-areas/black-holes Apr 9 '21 at 21:03
• @abestrange: Your black hole doesn't even need to be "rogue" in the sense that it's not following the galactic orbit. Stars don't move in lockstep — they move relative to each other while orbiting the galactic center, and occasionally they pass very close to each other. So your black hole just needs to be on a collision course with the solar system it's going to destroy. This is very unlikely, but only because space is so big. Apr 10 '21 at 11:25

Strangelet

Strangelets are fragments of matter made of strange matter. I.E. matter composed by roughly equal numbers of up, down and strange quarks.

So, the alien civilization is running an experiment for generating a high-density fuel by exploring the energetic possibilities of quark-gluon plasma. The strange* experiment needs copious amount of power, so they build it into a huge space station in an orbit very close to the star in order to be able to cheaply collect large amounts of solar light.

But then, something strange* happens. Something went really, really very wrong! The station explodes and a large core of strange matter (I.E., a strangelet) is thrown at relativistic speeds directly into the star. The strangelet quickly converts the star into strange matter, turning it suddenly a quark star or more precisely, a strange star.

Of course, the process of suddenly turning a main sequence star into a strange star, especially one that is completely uncontrolled and starts very assymetrically in the star, happens in a chaotically messy way and severely disrupts the star's structure. The result is that actually, not the entirety of the star is converted to a strange star, but some large parts of it are actually energetically ejected at relativistic velocities all at once. I.E., it blows up spectacularly into a very strange* type of supernova.

We need to consider that if you observe a supernova from 1 AU of distance, you will see it as a billion times brighter than the detonation of an hydrogen bomb pressed directly to your eyeball. This means that any planets in orbit will be quickly incinerated, vaporized and turned into a plasma.

What a strange* game over!

* pun intended

Relativistic Jets

Crossing the path of a relativistic jet could destroy a system with little to no warning.

As a black hole rotates, ionized matter gets pushed to the poles and fired off in a long stream. The faster the black hole spins, the greater the jet velocity. Spin fast enough and these streams approach the speed of light. The beams are strongly directional and have a diameter initially the same size as the black hole, though they spread wider over distance. https://en.wikipedia.org/wiki/Astrophysical_jet

These jets would both ionize and physically pulverize a solar system that crossed the path. Because of complex orbits, it is possible for a system to be in the path of a beam for just a moment or for extended duration. Because the beam is highly directional and moving at near speed of light, it may be impossible to have any early warning depending upon the angle of approach to the beam (closer to right-angle approach means less time in the penumbra of the beam so less warning). The jet could be coming from any black hole, even well outside our galaxy — there’s no way to monitor for all of them.

Leave the system in the beam for a short time and you have lifeless place with heavy radiation poisoning and lots of cratering. Leave it in the beam for longer time and you have planets physically etched and broken by speed-of-light machine gun spray of bullets impacting entire surface with explosive impact.

An Alcubierre hiccup

Either due to an engineering mess-up or just spatial anomalies fluctuating into being, the star and its closer planets were warped in a certain direction, whereafter they were either destroyed during the process or due to where they were warped to. You could have a known black hole in the area, for example, maybe it sucked on the edge of the space warp and then ate the star and planets. Or maybe the system was warped into a larger star, or whatever.

A local Rip

For some reason, the local expansion of space increased drastically enough to Rip all local structures apart. Since the metric inside the area would go to infinity, maybe from the outside the excitations of the field would be infinitely diffused, so anything resembling remnant matter moving towards far-enough-away colonies/outposts would be vaporous enough not to damage those colonies/outposts on impact? But you still might get an effect like when that one guy put his head in a particle accelerator...

I'll just quickly throw my hat in here. There is a part of quantum field theory that describes something called a "false quantum vacuum". How it works exactly is complicated, but the theoretical end result is a local or universal cessation of action from the fundamental forces, causing the absolute destruction of matter. As per it is a probabilistic function of the quantum field, it can basically happen absolutely spontaneously.

Physicists calculating the probability believe it to be extremely unlikely, and the scale of destruction is usually described on a universal scale, but this would be an occurrence with absolutely no warning and complete devastation.

• The problem is that the true vacuum bubble would expand at lightspeed. So nobody would be able to observe the destroyed system because anyone that could see it, will immediatelly also be destroyed. The bubble expand until all the universe is consumed. Apr 13 '21 at 3:04

No boom can make this happen.

You're talking about planets, "reduced to rubble" doesn't make much sense. By very definition planets aren't held together structurally (the definition requires them to be round due to gravity--thus gravity has overcome any structure.) They're held together by gravity, the only approximation I can see for "reduced to rubble" is more energy is applied than the gravitational binding energy of the planet, thus throwing the bits to infinity. Anything less and the planet reforms.

Ok, the outermost planet is Neptune. It's gravitational binding energy is 1.7E34 Joules. It orbits 4.17 light hours out. Uranus has a cross section of about 1.9E15 square meters. That means the energy density at Neptune's orbit must be at least 9E18 J/m^2.

Your observers are a light-week out, 40x as far. Thus they get 1/1600 the energy density. Thus the observers are hit with 5.6E15 J/m^2. You can make a ballpark approximation of the energy involved by covering the entire star-facing side of your observation platform with hydrogen bombs. (You're looking at 1.3 megatons per square meter.)

The only way you are going to deliver this kind of energy is a beam from elsewhere. Gamma ray bursters have already been mentioned but I do not think they come close to the energy density needed.

If you will accept a different way of wiping things out, the rogue black hole approach will do it. Playing with Universe Sandbox I was able to completely denude the sun with a close flyby with a 10 solar mass black hole, although some planets were captured by the black hole. I suspect a somewhat smaller one would have done it, but the editor leaves something to be desired, I'm not going to run a bunch of tests. If it doesn't get close to the inner system it can't rip off the inner planets. A poorly aimed 100 solar mass black hole left the inner three, albeit I don't think Earth was still inhabitable.

A wandering black hole, or a black hole made in a lab gets loose. If it crashed into the star, the star could nova. People on the colony are encouraged to wear sunblock. Planets are disrupted in their orbits and destroyed, or perhaps begin an unstoppable fall towards the star, joining an accretion (?) disk. It might be a long time before they contact the event horizon but the resources are as good as gone.

• Black holes don't work that way.
– Mark
Apr 17 '21 at 1:04

A Descendant of Ernst Stavros Blofeld, famed nemesis of super-spy James Bond, was shooting pool one day with some friends when he uttered the most terrifying phrase in human history... "Here, hold my beer."

What happened next stunned half a galaxy — which was fine with Amaranthos Ophiouchos Blofeld, who loves to be the center of attention. You see, what he did was hold the Capella star system1 ransom! What he didn't count on was the reigning oligarch, His Excellency, President for Life, Field Marshal and Doctor Rhamadahaman, Lord of All the Beasts of the Earth and Fishes of the Seas and Conqueror of the Aldeberan Empire and Cygnus Minor in Particular,2 calling his bluff. Nobody calls a Blofeld's bluff!

You see, a week before he'd been reading this historical article from Space.com where he learned...

The reversals take place when iron molecules in Earth's spinning outer core start going in the opposite direction as other iron molecules around them. As their numbers grow, these molecules offset the magnetic field in Earth's core. (If this were to happen today, it would render compasses useless as the needle would swing from pointing towards the north pole to pointing to the south.)

During this process, Earth's magnetic field, which protects the planet from hot sun particles and solar radiation, becomes weaker.

And that gave him an idea, what if he could play enough merry havoc with the molten iron in the core of every planet in the Capella star system that had a molten iron core just long enough, oh, maybe a couple of hours or so, to let the amazing solar maelstrom caused by four stars to gently barbecue the snot out of each planet?

Buahahahahahaha!

You see, what's happening here is that a planet's magnetosphere is created by the planetary liquid core, and it affects the planetary liquid core. In the case of Earth (which we will egregiously extend to all planets enjoying a liquid core), the inner core and outer core spin in different directions.

"Previously, there have been these two independent observations, and there has not been a link between them," study co-author Philip Livermore, of the University of Leeds, told LiveScience's OurAmazingPlanet. "We argue that the magnetic field itself is pushing on the outer core, and there is an equal and opposite push on the inner core." (Source)

What this means is that all one need to do to get the poles to flip (or, better yet, to almost flip) is to change the rotational speed of one of the cores (inner or outer) such that the compounded effect from the magnetosphere would be to create a metastable condition.3 In true Hollywood fashion, what we're trying to do is get the engine that creates the magnetosphere to stall... just for the proverbial second!

Amaranthos is convinced that one way to do this (one not previously considered by the greater scientific community)4 would be to change the rotational speed of one of the two cores. It doesn't matter which one, and it doesn't matter how much so long that it's enough to destabilize the balance between the two core rotations and the magnetosphere. Frankly, if you noted the progression of one of the poles, you probably could work out where to apply pressure to get it to move just a little bit more....

From a very simplistic point of view, it's like changing the gearing between a motor, a flywheel, and the load connected to the flywheel. If you rapidly and dramatically change the balance of energy, the system attempts to compensate — and the result can be spectacularly violent.

How did Amaranthos plan to do this? In true Blofeld style! He realized that he could sneak the millions of nuclear weapons needed to superheat the outer core of each planet (because hot things move faster, right? And it's so much simpler to heat things up...) into place without attracting anywhere near the attention that such an action would normally deserve. All he had to do was [Redacted for national security reasons] and when the Prefect of Greffetacle heard about it, he actually laughed out loud!

So, when old Rhamadahaman sent Amaranthos a text and called him an overrated blowhard good for nothing more than the entertainment of his troops... well, naturally, Amaranthos pushed the button.

And when the magnetosphere collapsed on all those planets, they were snuffed out, cooked to a crisp, and left irradiated for generations. As Blofeld said when he reclaimed his beer, "I pity the fool who tries to mine on one of those planets!"

1The planets are there. I'm sure of it. You just need to look harder! Try squinting....

2With all due respect to Idi Amin Dada Oumee, who never let common sense stand in the way of first-class title mongering.

3A fancy way of saying, "a moment where the darn planet doesn't really know what it wants to do."

4Did he forget to add "scientific god among men" to his title? I'm sure I left him a note to add it. I'll get right on that.

• I'm a little confused. What do you mean by "[Redacted for national security reasons]"? That seems like the part that would actually be the answer... You give me the concept behind the answer but don't actually explain what the answer is. This is a really well-thought-out answer with lots of description and an interesting way of answering the question, I'm just caught up with the Redacted part. Or is that what would be "handwaved" and everything else still works...? Apr 10 '21 at 5:20
• The whole idea doesn't work. A changing magnetic field does not make the planet unmineable, it merely requires some UV protection over the mining operations. And one planet having a magnetic reversal does not affect other planets at all. (Also, the style of the answer is overly... poetic, separating the narrative from the technical core takes mental effort. Apologies if I misunderstood the technical content.) Apr 10 '21 at 7:54
• Sorry, but I don't think that this answer makes any sense. Apr 10 '21 at 10:47
• @Mandelbrot At the time I wrote this, I didn't have the time to figure out how to deliver the number of nuclear weapons required to heat the outer core. However, how to deliver those weapons isn't within the scope of the question. In fact, it's story-based. So I ignored it with a little amusement. Apr 10 '21 at 16:41
• Note that even switching off the magnetosphere wouldn't have much of an effect. It shields the atmosphere from high-energy particles (not from UV as I mistakenly wrote), and that keeps the atmosphere intact - but the process of atmosphere erosion through solar wind is slow, somewhere between thousands and millions of years. So I think Blofeld will fail unspectacularly. Apr 10 '21 at 21:45