Would an endothermic star be possible?

Question

Real world stars are a mass of exothermic nuclear reactions. But what if there were some sort of star-like astrological phenomenon that somehow underwent an endothermic reaction?

I would like to know if the existance of this 'endothermic star' could be justified. Scientific explanations are preferred, but I'm willing to stretch to magic means if there are no plausible scientific explanations.

Further Clarification: Preferably something that has gravity/can be orbited, but ultimately anything that would have a cooling effect on other nearby celestial bodies.

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Note: I'm not actively writing a story, this is purely hypothetical for the time being.

Answer 1

Technically those do exist, they are called Type II Supernova, though the endothermic part is very brief and then followed by a very exothermic reaction. The exothermic nuclear reaction is what make a star a star. Once the nuclear reaction starts taking more energy than it gives off, like when attempting to fuse iron in large stars, it collapses in on itself. Stars are held up by radiation pressure from the nuclear fusion, without it they cease to be stars.

Otherwise, A star is by its very nature an exothermic reaction.

Edit

Has mass but does not warm a object around it. You could orbit a black hole that does not have an accretion disk. The cooling would come from space itself and for all practical purposes the black hole would give off very little heat.

Answer 2

There's a problem here: nothing is colder than deep space.

Since there is no interstellar medium, the only way heat transfers in space is by radiation. Any object facing deep space and not illuminated by a star or itself will, left on its own, gradually cool to a little over absolute zero, heated only by the cosmic microwave background radiation.

There's no way to "suck" heat out of something that's not being radiated in that direction. You could have planets orbiting a dead star that emits nothing, or possibly a planet that is a wanderer, and they would be extremely cold; any remaining atmosphere lying frozen as a blanket of snow.

Answer 3

This is probably nutty, but something like adiabatic magnetic refrigeration might work. https://en.wikipedia.org/wiki/Magnetic_refrigeration

Imagine taking the iron core of a dead star. Apply a mind-bogglingly large external magnetic field, using something like solar-system-wide Helmholtz coils. Maybe Magneto could do it. Anyway, once the system equilibrates to the new high field, the iron core will be magnetized, meaning all of its magnetic domains are aligned along the field.

Now start to lower the externally applied magnetic field. I'm not sure how to estimate over what timescale it can be lowered, but there would be an incredible amount of energy stored in a stellar core sized chunk of iron, so I would guess centuries just comparing that mass to a standard adiabetic magnetization refrigerator mass.

As the magnetic field decreases, the core's magnetic domains will start to randomize by absorption of thermal energy. But until the magnetic field is zero, the domains will reorient themselves to this lower energy state, resulting in a "spontaneous" decrease in entropy, cooling the body. So over whatever time scale you lower the magnetic field, the body would overall be colder than surrounding space, with the cooling power equal to the decrease in stored magnetic energy over time.

It would be artificial to set up, but in principle it could be a relic from an older hyper-advanced civilization, with the magnetic field machinery just now decaying when we find it.

Answer 4

Black holes are endothermic in a sense, although their swathe of destruction causes an exothermic signature.

I guess cold neutron stars could be endothermic, as their neutrons evaporate. It's complex, because these mechanisms are quantum physical rather than chemical, but in the sense of absorbing heat rather than emitting light you have to go to the dark side - certainly endothermic stars couldn't emit black body radiation.

Answer 5

For the purposes of writing a science fiction story, these answers are not necessarily satisfactory. The concept of an endothermic star might appear in the mind to be an icy blue sphere of radiating energies unknown to modern physics. In reality, the concept is quite different.

For something to be endothermic, it must absorb energy from its surroundings, but this is not seen in space typically. In space, where the radiant temperature is a few Kelvin, there are limited sources of energy for such a star to feed off of. That is, they are limited but not nonexistent.

Recently, the discovery of gravitational waves has made ripples (sorry) in the scientific community. It is conceivable, with a bit of a stretch, that an endothermic star could be at a nexus point between multiple binary star systems, where each creates gravitational waves that pass over the endothermic star, and the waves enter a superposition of energy at this point.

The energy in the space of the star could be used to help heavier elements undergo nuclear fusion (remember that the fusion of elements heavier than iron requires more energy than it could release, making the process endothermic). This star would still release some light, and thus it would work perfectly in a science fiction novel. Attached is an image of what the system would look like, with the scale of distance being in hundreds of light years.

Answer 6

Would a black dwarf be endothermic? Black dwarf stars are a theoretical type of star that has not yet had sufficient time to form in the universe. It is hypothesised that our own Sun may end its days as a black dwarf a quadrillion years from now.

Answer 7

There is a very general problem with your request: A true and permanent radiation sink violates the second law of thermodynamics (you take entropy away from the universe). This law is among the most universal laws in physics; it governs black bodies and black holes, indeed it probably governs the universe as an entity as well.¹

Now that law only applies to closed systems. Maybe what you are looking for is a processor cooler at a stellar scale? That is, a mechanism to guide the heat away from the star and emit it "somewhere else". If you don't want to have an orbiting heat pipe² (it's orbiting so that it's always behind the cold star and does not spoil the view) I'd suggest a mechanism like magical micro mirrors (the marketing term was m³) that reflect incoming radiation at an angle perpendicular to all three spatial dimensions. Poof, gone. Make sure it is a one-way mirror though (you know, the second law).

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¹ See, for example, the Wikipedia article on the holographic principle.

_{² Siphoning (nice word) the energy "away" would, in turn, use more energy, just like your fridge or your CPU cooler. The colder you want the object, the more energy you need to stem the natural flow of entropy. On a stellar scale you probably need a stellar energy source (something like a death star 2.0 turned beer cooler). That energy source / working star would better be far away because actually you seem to want it cool, locally. So you would need a massive energy conduit from a working star to your (very) dark star, and then the heat pipe going "away".}

Answer 8

In the Electric Universe Theory/Hoax stars are "sumps" that soak up all the cosmic electricity around them. I think the idea is that a star's electromagnetic field is the source of gravity, and the star "burns" because the flow of ions is concentrated there. The electricity comes from outside the star, and the visible star is just an artifact of this electrical phenomena.

I've read a few articles that discuss this concept, or rather, I tried. The logic is often circular, and the whole concept is probably magic dressed up as pseudo-science. Here (or here) is a heady article with I think explains the concept in detail.

Answer 9

A normal star emits "warm radiation" which adds energy to anything that absorbs the radiation. What you seem to want is a source of "cold radiation" which subtracts energy from anything that absorbs it.

Something like this doesn't exist in physics. Well, there is laser cooling, but that only works on individual atoms under lab conditions.

So you would need to make up some form of fictional electromagnetic anti-radiation which is emitted by some kind of equally fictional exotic matter which the star consists of.

Answer 10

I think if the author were to have his characters declare that the body cannot be truly endothermic due to the second law, it would be a great starting point to having them look for where the energy is going. Finding out where could be a great quest for an entire series.

You could pick various of the answers here and use a separate story to explore what that answer predicts would be the 'trick' that would allow the phenomenon to appear as a perfect endothermic body. Then have your heroes prove that that trick doesn't exist.

And you could pick your favorite and have them find the secret in the last episode. Irony would have it turn out to be something of a hoax (Miniature storage cells with massive capacity being charged up to power the RV of a cute EBE family.)