Celestia Forums

I'm quite intrigued by these superflares described for some G type stars (eg Kappa Ceti). I'm primarily interested in them because they provide an ideal scenario to kill lots and lots of people on Earth without actually destroying it - don't worry though, it's only for a sci-fi backrgound I'm writing

My original plan, before I heard of these superflares, was to have the sun to suddenly shed its outermost layers, which would melt half of Mercury and the Moon, and blast off most of Venus, Earth and Mars' atmospheres. But these flares sound much more realistic (at least in the sense of being possible )

So I ask the assembled astronomical minds here, what do you think would happen if the sun was to superflare? What would the sequence of events be? Would the whole star suddenly brighten dramatically, or would it be focussed in a particular direction (if so, assume it points at Earth here). Would an entire hemisphre brighten? Or just part of it? Presumably, since it's got something to do with mangled magnetic field lines, sunspot activity would be going through the roof in the days or weeks beforehand, so that might give us some warning to start evacuating the planet (this is a scifi background, remember ) .

I'm figuring that there'd be two effects, lasting over say, a week or two - the increased luminosity and the actual material blasted out by the flares. When the flare actually starts on the sun, we'd see the brightening from it 8 minutes later, but presumably the material ejected by the flare wouldn't arrive til later - how much later though? What effect would the incoming flare material have on the Earth and other planets? Could it physically blast away atmospheres? And how much would the sun brighten by - the solstation site says it could increase by up to 1000 times?! The increased temperature would surely boil oceans and drive off atmospheres too, wouldn't it? Or would there not be enough time to do that if it only lasts for a week?

Any conjecture or hard fact would be most welcome .

Evil Dr Ganymede,
I read a book several years ago that was a sci-fi that kind of played off this idea. It wasn't mentioned right out in the story but if you had half a brain you could see the direction the author was taking. The book was called "Night Eyes". At first when you start reading it you think it is just another story about aliens visiting the Earth. You know, the grays. But as the story evolves you find that the aliens are not really aliens at all but engineered humans from very far in the future and they have come back in time to gather history, which was lost during both a cataclysm and a war with another space faring species that wasn't so nice. Of course the author has a really cool out for the problem of paradox. Simply there won't be a paradox because there just isn't going to be anyone left on Earth that could cause a paradox. Meaning that anyone that came in contact with them for any reason, even if they told the whole world it would still have no change. Meaning in the story the human race is totally taken out except for maybe a hundred people in a very isolated location in New Zealand of all places. Everyone else gets killed off by massive amounts of radiation from space that comes from towards the sun. Cool idea and it definitely sounds like some kind of super flare. There are allot of other sub-plots going on but this is the main idea of the story. If I have a chance next time I go to my storage unit I will see if I can find the book and post the authors name. I would consider it a good read. It has some neat ideas to work with. But your ideas aren’t to shabby either.

Don. Edwards

Oh Evil One,

I would expect that, to first approximation, the timing of particles and radiation arriving at the earth wouldn't be much different from the CMEs (coronal mass ejections) that we've already experienced -- just on a much larger scale.

One place to start your research would be http://science.nasa.gov/ssl/pad/solar/cmes.htm

I read somewhere that a superflare is triggered by a magnetic reconnection event between a star and a gas giant in close orbit. As far as I've heard the interaction between the Jovian and Solar magnetic fields isn't strong enough to cause that kind of eruption, but since nothing has been found around Kappa Ceti, it is not yet determined if epistellar Jovians are a requirement.

Such an event would probably melt the ice on the moons of Jupiter and Saturn, leaving behind smooth featureless plains. Suffice to say, it would make any concerns about the ozone hole academic...

Speaking of CMEs, that brings to mind a related question: When we talk about flare stars and superflares on other stars, what are we actually seeing? Are we seeing the 'halo events' described on the website that Selden linked to - i.e. are we seeing an individual big flare that is firing off in our direction? Or are we seeing many smaller flares going off?

And when they say that flares can last up to a week, does that mean that the actual flare event lasts for a week, or that the stuff that's ejected and coming towards us staying luminous for a week?

How much does the averaged luminosity of Sol change over the course of a big flare or CME anyway? If you were a few lightyears away looking at sol, and happened to be along the axis of a CME, would you see Sol increase in brightness slightly?

chaos syndrome wrote:I read somewhere that a superflare is triggered by a magnetic reconnection event between a star and a gas giant in close orbit. As far as I've heard the interaction between the Jovian and Solar magnetic fields isn't strong enough to cause that kind of eruption, but since nothing has been found around Kappa Ceti, it is not yet determined if epistellar Jovians are a requirement.

That's what I've heard too, but it seems the important thing is that the star's magnetic field gets all mangled up and then manages to sort itself out somehow. It sounds like what happens at the end of a sunspot cycle (IIRC), when Sol's magnetic field lines get all gnarled up and then they straighten out. But on a much, much bigger scale.

I realise it's not something that seems to be likely to occur naturally for Sol , which is why it might need a little... artificial encouragement .