A question regarding the physics of the sun

[Crescent Pulsar R]

Well, there's this idea that came to mind, for a story, but I didn't go to Fic Research since that seems to be a better place for getting information about a given series itself. Plus, it's an idea for a story that I haven't really fleshed out in my mind, since I may or may not have it fleshed out depending on what I learn here. So, given that said story doesn't really exist yet, I thought I'd do it this way.

So. What I was wondering is: if the the magnetic field of the sun became stronger, and (thus?) exerted more compression, would the entire surface cool and darken like a sunspot?

Yeah, if it sounds like a dumb question, that's probably because I dropped out of high school (ninth grade) eleven years ago (considering the question, what a coincidence!) and haven't had any formal education since.

[Spokavriel]

If the sun somehow increased in mass but not matter it would in theory compress and shrink. But given the theorized density of Dwarf stars it is just as likely it would get hotter or detonate.

[Shanami]

That's actually a virtually impossible question to answer for multiple reasons, but here goes to the best of my ability. Oh, and I've a good friend and his parent that work basically in astrophysics studying the sun that I can possibly get slightly more accurate info from.

First off, the magnetic field of the sun is in no way uniform, and increasing the compression would cause multiple effects, first, we have to look at the basic fusion reaction that powers the sun. Basically, 2 hydrogen atoms slam into each other with incredibly high energy and fuse to make helium, this releases yet more energy, The helium then continues to fuse with other helium, eventually culminating in iron, which is too heavy for effective fusion to take place. Adding compression to the sun would actually force the molecules in closer to each other, so if we did not change the initial energy, the reaction would take place much faster.

However, as the magnetic field is not uniform, changing it in different places would cause different isolated phenomena. But, a uniform increase in compression would probably increase the rate of reaction, causing the sun to heat up. However, the magnetic field would allow less radiation to leave the sun, in essence, it would cool the rest of the solar system. Less em radiation and light escaping the sun would lead to a cooler solar system. Black holes are essentially hyper compressed, and their event horizon prevents all EM radiation from escaping, thus they cannot be visualized. It would cause the sun to look visibly duller, and the escaped heat would probably go down.

Now, this is something of speculation on my part, because if you increase the pressure of a system too much, it can cause repulsive forces to increase, thus slowing a reaction. However, in general, higher pressure (aka compression) = faster reaction, along with higher temperature = faster reaction. These would compound each other, probably under the general circumstances you dictate.

Was that useful, or would you prefer I explain differently?

[Spokavriel]

Your description of black holes sounds like the definition from before the final collapse into the singularity.

And unless it is increased enough to nearly collapse there is a long way to increase the gravity on the mass before the point of collapse. And that also leaves a sizable margin before the mass restricts the radiant releases. (Look at the clasifications of stars and measured densities along with light and heat intensities) I find it more likely the system would be burned to cinders before it got to the point where it would cool.

And with the options in the situation where the total mass remains the same going to cascade or collapse for the options. The sun is already in an active but relatively moderate state of cascade already. So going to the point where light would be restrained would also equally provide the chance for cascade failure (detonation) or collapse giving us a black hole. Both of which would most likely destroy the rest of the solar system if the occur.

[Crescent Pulsar R]

Hmmmm... I think I understood everything until the part about how those two things compounded each other. Does that mean they would cancel each other out, have an unknown affect together, or simply be unable to happen at the same time? Or something.

But, yeah, same mass. The added pressure would be due to unnatural means. Nothing more than what I think is applied around areas with sunspots, if I understand how that works right. I'm not exactly sure what kind of effect I'd prefer, which would cause the Earth to become significantly hotter or cooler as a result. I'm just trying to think up how an enemy (yeah, Sailor Moon stuff) can attack the sun, in order to effect the Earth adversely. Especially in a way where they wish to destroy the sun in order to do so, but in a way that gives the senshi enough time to defeat them before the effect on the sun gets bad enough for it to cease to function as a star.

And while this sort of thing is out of my element, I figured I'd try my hand at a Sailor Sun/Sol story.

[JustinD]

Just to add definition to a sun spot, I'd like to add that they only appear black due to contrast to the rest of the sun and if isolated from the rest of the sun they would appear to be very bright and not black.

[Knight of L-sama]

Your question is hard to answer because one of your basic assumptions is... well wrong. The Sun's magnetic field, while impressive on a human scale (if you want impressive on a stellar scale you have to start looking at pulsars and magnetars) has absolutely nothing to do with the sun keeping its shape. That's all done by gravity and it is the energy of gravitational compression that provides the heat necessary for nuclear fusion to happen at the core. Most of the funky magnetic features happen in the photosphere (so named because its the part where it becomes transparent to visible light photon) because that part of the sun is literally boiling which causes the magnetic field lines to get twisted, tangled and all in all a total mess that's complicated by the fact that the sun is rotating but different depths rotate at different speeds.

Misunderstanding of solar magnetohydrodynamics asides anything that can exert a compressive force at the sun is going to increase the temperature of the core which is going to increase the rate of fusion which is going to increase the energy output of the sun and thus make it brighter.

[Ellen Kuhfeld]

The magnetic field of the sun is a complicated thing. Since the sun is fluid, it doesn't rotate rigidly; the inner portions spin slightly more rapidly than the outer portions. Since the sun is hot, the gases are ionized. Ionized gases conduct electricity, and interact with the magnetic field. As a result, the outer regions of the sun drag the magnetic fields of the inner regions along, and the field gets wound-up and very complicated. (Nowhere as neat as we have on Earth.)

This all happens during the sunspot cycle. When the field is really wound-up and tangled, the field lines will snap and rejoin. That throws off a nice magnetized bubble of hot solar gases - it's called a flare.

It seems likely that increasing the sun's magnetic field would give a much more pronounced cycle of sunspots and flares; sorta like people when they have too much coffee.

[Spokavriel]

There have been a few times documented where earth passed through Solar Flare discharge. It was enough to increase static on radios of the time but nothing on a scale of science fiction where things got burned away because of the flare...

[Ellen Kuhfeld]

There have been a few times documented where earth passed through Solar Flare discharge. It was enough to increase static on radios of the time but nothing on a scale of science fiction where things got burned away because of the flare...

That's true of the flare itself, though satellites are vulnerable. The magnetic field that wraps up the particles is much worse -- it pushes the Earth's field around, and that induces surges in power lines and such. We've already had power outages from solar magnetic storms. The more our power and communications nets spread over vast areas, the more susceptible we are.

[Shanami]

The interesting thing would be to see what would happen if you were to uniformly apply a magnetic field to the sun, which is what I interpreted your question as asking. The earth's magnetic field is significantly more stable than the sun's (though it still fluctuates quite substantially on a geographic timescale) it would be very interesting to see the effects of a powerful, uniform magnetic field applied to the sun. Granted, with fluid dynamics and the fact that the sun is hot enough to produce plasma, the effects would still be damn near impossible to predict.

[Crescent Pulsar R]

Thanks for the input, everyone. It sounds like I should probably describe the effect and not the dynamics behind it.

[Pale Wolf]

Hmmmm... I think I understood everything until the part about how those two things compounded each other. Does that mean they would cancel each other out, have an unknown affect together, or simply be unable to happen at the same time? Or something.

They increase one another.

Heats up. Drastically.

It'll get hotter, not colder. Much, much hotter.

The formula for the pressure of a gas is P = n * R * T / V. P is pressure, of course. n is how much of the gas is in there - this isn't going to change. R is the gas constant, it's not going to change so it's not really relevant to your question (though, it's 8.314472 if you want to broaden your horizons). T is temperature. V is volume.

You're increasing the pressure - mathematically speaking, you're multiplying the whole equation by let's say 1.3. Now, that increase has to come from somewhere on the other side of the equation. R's not going to change (don't go breaking fundamental physical constants! ). You can either increase the amount of atoms, decrease the volume, or increase the temperature. Any one of these things will, however, have the same effect.

The atoms are either closer together, there are just more of them in the same space (same effect), or they're moving a lot faster. (Faster atoms = higher temperature) This means they're hitting one another a lot more, and therefore, they're setting off a lot more fusion reactions - increasing the temperature even further.

Which again increases the rate of reaction, which makes things even hotter...

[Crescent Pulsar R]

Wait, that sounds like a feedback loop, right? :O

[Spokavriel]

Cascade reaction. Each reaction setting off further reactions.