CME deflection in "Echoes"

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CME deflection in "Echoes"

Post by l33telboi » Fri Mar 16, 2007 3:11 pm

I thought i'd bring up this Stargate Atlantis event on this board, to see if there some more knowledgeable people here who can make sense of all this. First, a little background to get those of you who haven't seen this episode up to speed on what exactly is going on.

A CME threatens to "take out" an entire planet and the Atlantis expedition decides to send a ZPM powered BC-304 to deflect the CME before it can reach the planet. Here are some images that will better explain what's going on.

The problem with this episode, is that the VFX does not even nearly mesh the dialogue and i'll do my best to describe all the discrepancies as i go.

Here's an image depicting the BC-304 holding place and ready to intercept the CME:

Image

And it's also the first contradiction between dialogue and visuals. Dialoge says that the BC-304 will have to be extremely close to the surface of the sun to deflect the CME before it has the chance to start spreading out and then even says that the CME will be large enough to take out the entire planet after "a few million miles", and in that picture, the 304 seems to be at least a whole solar diameter from the planet.

Next up is an image of the CME spewing out from the sun:

Image

As you can see, we're talking about an extreme narrow and dense plasma jet, something normal CME's shouldn't be. And again, dialogue says that this should dwarf anything our own sun has ever emitted.

Next up is an image of the CME striking the actual 304:

Image

As you can see, the plasma jet has yet to expand almost at all, something that shouldn't be possible by normal physics, unless there's something holding it together, perhaps magnetic fields or whatnot, i don't know.

In any case, this is all supposed to portray an incident that will kill all life on a planet and dwarf anything that ever came from our sun. Yet it looks nothing like it.

What's your take on things? Can this event be explained? Can there be any figures derived from all this?

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Post by Mr. Oragahn » Fri Mar 16, 2007 3:36 pm

We could have safely derived a figure from this if the Daedalus had expanded her shield, like Atlantis did.

Look, even the former explosion on the photosphere it is already planet sized, and would dwarf Earth I think.

So we have that thing, magically held tight inside some kind of conundrum.

Only super speed could compensate for the natural expansion. And yet, I'm not even sure it's possible, because gas expansion in vacuum, with the yield considered, would not allow such a cop out.

Even a sun's magnetic fields can't compress solar ejections that way. They're not compressed that much at all in fact. Just kept hot.

Super dense matter that keeps everything packed?

Is it gas then? maybe more solid melted particles? Then it would be possible I guess.

See, an ocean of super molten material spread over the whole exposed surface of a planet would indeed cause a massive extinction of any life.

Eventually, could it be some kind of matter that was in the core, expelled violently, like a pouch of matter, resulting from the absorption of a bigger solid body million years ago, that gets super heated every thousands of years, and turns into that super compressed jet?

Of course, could matter remain only melted? And how would that fit with a CME that would dwarf anything our sun can output?
How a CME, by definition, be about non vaporized matter?

In fact, we never learned if the former jet was so tight.

Or should we disregard visuals and stick with dialogue, which at least remain plausible?

What should have happened should have displayed the ship engulfed within a multi km wide CME, and the single effect of deflecting matter at such a distance from the sun and the planet would have been enough to create a blind spot and make the rest of the CME pass the planet without touching it.

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Post by Mr. Oragahn » Sun Mar 18, 2007 3:35 pm

Here are some key pieces from the transcript:
SHEPPARD: Adaris is a ship we found in the Ancient database.
McKAY: It’s an Ancient science vessel. About fifteen thousand years ago, it ran into some trouble. The entire crew was killed except for the pilot.
WEIR: The burned man. Teyla noticed the uniform. He was an Ancient pilot.
McKAY: Which would explain the burns.
ZELENKA: What does?
SHEPPARD: The ship got hit by a blast of radiation from the sun.
McKAY: It’s a coronal mass ejection on a scale that dwarfs anything our sun has ever emitted. Apparently the sun in this solar system goes through an unusually turbulent sunspot cycle every fifteen thousand years or so. The Ancients have records of this class of CME occurring twice before.
SHEPPARD: The ship was very close to the sun when it happened.
McKAY: It’s a massive prominence. It arced up and then collapsed when the magnetic field surrounding it weakened. We’re talking an intense proton stream travelling at over four thousand kilometres per second.
SHEPPARD: Most of the crew was killed instantly but the pilot managed to open up a hyperspace window just as they were hit. He flew the ship back here, jumping ahead of the radiation wave just in time to warn everyone.
McKAY: The Ancients were able to raise the shield and extend it far enough to protect a large portion of the planet from the blast.
WEIR: So what are you telling me? This is going to happen soon?
McKAY: Not soon. It’s happening right now.
(He turns the screen of his laptop towards her. It shows a prominence curling out from the edge of the sun.)
CONTROL ROOM. The image of the coronal prominence is now on a large screen.
McKAY: The magnetic field around it is already beginning to weaken. When that prominence collapses, the coronal mass ejection will occur. It’ll erupt from a very small area – a mere pinprick in comparison to the total sun’s surface, but it’ll immediately begin to fan out. Within a few million miles, the blast wave will cut a swathe wide enough to take out this entire planet.
SHEPPARD: How much time do we have?
ZELENKA: The prominence will collapse any moment now. After that, we have less than an hour before the radiation wave hits us.
WEIR: Why didn’t we notice this before?
McKAY: Because these things happen very quickly.
ZELENKA: This kind of sunspot cycle is extremely chaotic – impossible to predict. No doubt that’s what caused the glitch in the Jumper’s navigational systems.
McKAY: Not to mention our focus was on attack from the Wraith, not the sun.
POWER ROOM. Rodney sighs as the ZPM rises up out of its slot.
McKAY: This is not a good plan.
SHEPPARD: Sure it is.
McKAY: You realise just how close we’ll have to get to the sun?
SHEPPARD: Pretty damned close, I’m thinkin’.
(He picks up the case for the ZPM and opens it.)
McKAY: Suicidally close. I mean, we’ll be toast.
SHEPPARD: That’s why we’re taking the ZeePM – to give the Daedalus’ shield an extra boost.
McKAY: OK, OK – you want to deflect the coronal mass ejection away from the planet.
SHEPPARD (taking the ZPM out of its slot): Like an umbrella.
McKAY: OK, listen to me. (He picks up his computer tablet and starts to draw on its screen.) This ... (he draws a big circle in the bottom right hand corner) ... this is the sun; and this ... (he draws a small squiggle in the top left hand corner) ... this is us.
(John frowns at the drawing as he puts the ZPM into its case.)
McKAY: A bolt of energy unlike anything you could possibly comprehend is gonna shoot out of the photosphere at a tremendous velocity, OK? (He draws a line coming out of the sun and heading towards the dot depicting Atlantis.) It is immediately gonna start fanning out ... (he draws lots of lines fanning out in different directions from the line) ... like so.
SHEPPARD (impatiently): I know.
(He goes over to the power console and bends down to retrieve something.)
McKAY (drawing a curve across the emission line to depict Daedalus’ shield): Which means that we will have to be really close to the surface of the sun if we wanna intercept that stream and deflect it before it can start spreading out.
SHEPPARD (popping back up into view for a moment): I know, Rodney! (He bends down again.)
McKAY: No, no, I don’t think you do. I don’t think you fully grasp the reality of just how damned hot it gets that close to the surface of the sun.
(John has retrieved a small device from the console and comes across to the case with it.)
SHEPPARD: That’s why we’re taking a ZeePM – to strengthen the shields.
McKAY: From the blast wave, yes, but even with the shields at that strength, the build-up of residual heat behind it could cause serious problems for the Daedalus ... (he points to himself) ... and everyone inside it.
(John puts the device in the case and closes the lid.)
SHEPPARD: “Could”. “Could” cause.
(Rodney sighs.)
McKAY: OK. Tell me ... (he shows John his drawing again) ... if this is such a great plan, why didn’t the Ancients do it?
SHEPPARD: They were in the middle of a war! They probably didn’t have a ship available at the time. And, like you said, they had three ZeePMs.
ZELENKA (over radio): Rodney?
McKAY (irritably): What?
ZELENKA: The prominence has begun collapsing.
(John picks up the case.)
SHEPPARD: Colonel Caldwell, we’re ready.
(Rodney grimaces. A transporter beam envelops the pair of them and whisks them away.)
Daedalus breaks orbit and heads towards the sun. Inside the ship, Rodney is connecting the ZPM to the shield generator.
SHEPPARD (over radio): How’s it going, Rodney?
(Rodney rolls his eyes in irritation.)
McKAY: You know, this might look easy, but it’s actually a little more complicated than just flipping a switch.
(He walks across the room, trailing a cable behind him, and pulls open a panel of crystals.)
CALDWELL: Hurry up, please. We’re there.
McKAY (his eyes wide): What, we are already?
CALDWELL: Not far to go.
(Rodney rolls his eyes again and gets on with connecting the cable to the crystals. Daedalus heads closer to the sun. On the Bridge, everyone is bathed in bright sunlight. Caldwell takes his place in the command chair while John stands nearby.)
CALDWELL: Position, Doctor. The shields are up. We need the extra power from that ZeePM now.
McKAY (irritably): Yes, yes. I just need to ...
(He turns from the crystal panel and trails off as he sees the wall screen.)
McKAY: Oh no.
SHEPPARD: What?
McKAY: The prominence is fully collapsing into the photosphere. Brace yourselves.
(He grabs his tablet and starts working on it. On the sun’s surface, the emission bursts out and heads into space. John stares.)
SHEPPARD: Rodney?
McKAY: ZedPM is online.
(The emission heads towards Daedalus and impacts its shields, which deflect it away in all directions. Caldwell squints as the bright light envelops the shields and the ship vibrates under the strain.)
CALDWELL: How long will this last, Doctor?
McKAY: Anywhere from a few seconds to several hours.
SHEPPARD: Hours?! You never said anything about hours!
CALDWELL: We’re building up serious heat behind the shield.
McKAY (plaintively): I told you this wasn’t a good plan!

ATLANTIS CONTROL ROOM. Ronon is looking at a laptop with Radek. Both of them look strained from the consistent headaches.
DEX: How’re they doing?
ZELENKA: Well, according to my calculations, the blast wave should have hit us by now but I’m reading no discernable increase in radiation.
(Ronon stares at him. Finally Radek realises and turns to look at him.)
DEX: So they’re doing good?
(Radek smiles.)
ZELENKA: Yes. So far, anyway.
Ancient war timeline error aside, we can see that what was scripted and even planned is nothing of what we got on screen. Both script and intent disagree with visuals. Even science heavily disagrees with visuals.

They were supposed to sit close to the photosphere, up to the point where even their shields wouldn't protect them from the sun's natural emissions, without considering the CME.

The visuals are just simply completely wrong. They're nice to look at, but completely inaccurate.

So I'd suggest to treat the info like if it was from a book, and make the calcs from that.

Technically, the ship should be close to the photosphere, and literally dousing into a country wide CME.

There would be two things to consider about the calcs.

First, the kinetic impact of those particles. This means that considering the shape of the shield, you'd have to consider the angles, for the work. Since the shield will not present a flat wall, perpendicular to the stream, but rather a tight ovoid egg like form, assuming an angle of 45° could be a necessary average, to cut down the real force.
By the way, since the ship had to hold still, and since it was never declared as being impossible, we'll be able to dismiss any claim about the ship being pushed back from anyone who would think the relative KE against the shields would have been less than the numbers ought to be found.
The stream's speed was over 4,000 m/s.
Calculating the KE alone won't be enough. We'll need to cut it through shield area and angle.

Secondly, there's the thermal radiation itself. That's two parts. First, from the sun's own natural emissions. Secondly, from the stream. This is where it's tricky, because the radiations will not only come from the front, but also be radiated by the matter that flies by the ship.
This will require to know the initial width of a typical solar CME.
This part should probably be the hardest.

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Post by l33telboi » Sun Mar 18, 2007 10:12 pm

If we'd go by the dialogue only, then we'd most likely be able to jettison the KE calcs done earlier altogether, as plasma normally isn't all that dense, and thus isn't able to give off a high KE.

What would be more important would be the heat. There were some numbers on this going in the "Solar Flares & Borg" thread already, if we'd be able to get the density of the plasma in a normal flare or CME, then we could probably use the figures there to aid in this.

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Post by Mr. Oragahn » Mon Mar 19, 2007 2:44 am

I got to check that thread.

I'm still stuck trying to figure where the ship was regarding McKay's "cut a swathe" comment.
Actually, I don't really get the meaning of that sentence.
What's important is not how wide the stream will be a distance x, since no matter what happens, the stream would expand and embrace the planet as a whole, but on the contrary, how close they need to be to the star to intercept the matter and create a blind cone which will contain the planet.

So, we estimate the size of the planet. We estimate the size of the ship+shield.

We consider the CME's departure disc (before it fans out), and reduce it to a point, by assuming that the ejection will inflate, so each molecule will try to get farther from the sun, opposite from the star's gravity center.

That is, only to know where the ship was.

Knowing the magnitude of the CME will be necessary to gauge thermal radiation.
We'd have to take the most impressive CME ever recorded for our sun, and take it as a low end.

As for the plasma, I don't kow. I mean, sure, it has a density even lighter than air at sea level I think, but it's still some kind of high velocity that blows at 4000 kilometers per second. I admit I haven't played with psi and pascals enough to realize how weak that may be.

A few sites with numbers about sun densities:

http://solar-center.stanford.edu/vitalstats.html

http://www.plasmaphysics.org.uk/research/sun.htm

And other about CMEs:

http://helios.gsfc.nasa.gov/lasco_4_7_97_cme.mpg

http://helios.gsfc.nasa.gov/cme.html


No stream deedadadoo.

That Echoes CME was apparently like more than twice the biggest CME recorded.

It's sad, really.

Image

Just looking at a few sites within a couple of minutes, we immediately see how completely wrong the visuals are.

I mean, when you bother to come with numbers about how the CME dwarves what our sun has ever 'outputed', forwarding numbers goggled around, you wonder how they could have missed that.

Really, screw visuals here.

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Post by l33telboi » Thu Mar 29, 2007 2:17 pm

A random thought popped into my head a while ago. The biggest problem with fitting visuals to dialogue is the fact that plasma usually isn't this confined, it spreads out.

Well, there is a something which involves particles, like the ions in plasma, being very directed and which doesn't spread out. Namely, particle acceleators.

What if something down on the surface of that sun is creating a particle acceleration effect? I.e. all the ions are travelling in a more or less direct stream at extreme velocities?

EDIT: On second thought, no. The speed is still way too slow. Though if one follows dialogue on how long it took the beam to reach the Deaddy from the suns surface and the visual of how far away the deaddy is, then we could possibly be talking about something extremely fast.

However, then we'd have to forget the slow-moving stream we see shooting out.

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Post by Mr. Oragahn » Thu Mar 29, 2007 4:29 pm

The particle accelerator requires powerful magnetic fields for not so formidable levels of energy (yet), and once those particles would exit the equivalent of that PA, they'd bump and spread.

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Post by GStone » Sun Apr 22, 2007 4:08 pm

At least, when it comes to the number of CMEs, we cna say that the others were not in view of the camera, nor were the directions of the emissions, while they were erupting.

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Post by Mr. Oragahn » Wed Apr 25, 2007 10:50 pm

GStone wrote:At least, when it comes to the number of CMEs, we cna say that the others were not in view of the camera, nor were the directions of the emissions, while they were erupting.
I'm not sure to understand what you mean.
That said, I'll reiterate my position on this: ignore the visual entirely.

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Post by GStone » Thu Apr 26, 2007 5:18 pm

If there are multiple CMEs, only seeing one can be from the others and their emissions not being in range of the camera.

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Post by l33telboi » Thu Apr 26, 2007 7:04 pm

GStone wrote:If there are multiple CMEs, only seeing one can be from the others and their emissions not being in range of the camera.
The episode suggests that this is the only thing the Deaddy expected from the star. If we go by visuals, they would've had to calculate quite exactly where to position the ship even before the CME 'erupted'. So if there were others, there was no mention of them.

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Post by Mr. Oragahn » Sun Jun 03, 2007 1:14 pm

Based on the previous agreement that the simply impossible visuals should be ignored in that case, let's run calcs just like we had ben reading a book, that is, solely based on dialogue, and eventually any other description - which may be visual mind you - but not directly tied to the uber CME visuals.

First, let's link to this interesting thread from spacebattles.com:

http://forums.spacebattles.com/showthread.php?t=110656

A couple of comments.

First, Akaviri assumed that we could take the level of rems spotted on Moon's surface, during the CME incident of 1972, and consider that at an altitude of 50 km above Earth, sufficiently out of most of the atmosphere, the level of radiations would have been the same.
I agree with the assumption, since the moon ir orbiting Earth, the obvious average distance "Sol <-> Luna" is going to be "Sol <-> Terra".

Later on, an issue was raised about how long it took for the blast to reach Lantia.
It's not clear which blast they're talking about. Obviously, the stream travelling at 4000 km/s couldn't touch the planet within +8 minutes. However, the EM radiations could.
So it's obviously been dissociated.

Above all, for the episode to make any sense, really, even with visuals out, we have to assume that the CME started as not being bigger than the 304, otherwise, no matter where the 304 was placed, most of the radiations would have hit Lantia.



I'll repost bits of the script, and outline elements of importance.
SHEPPARD: Adaris is a ship we found in the Ancient database.
McKAY: It’s an Ancient science vessel. About fifteen thousand years ago, it ran into some trouble. The entire crew was killed except for the pilot.
WEIR: The burned man. Teyla noticed the uniform. He was an Ancient pilot.
McKAY: Which would explain the burns.
ZELENKA: What does?
SHEPPARD: The ship got hit by a blast of radiation from the sun.
McKAY: It’s a coronal mass ejection on a scale that dwarfs anything our sun has ever emitted. Apparently the sun in this solar system goes through an unusually turbulent sunspot cycle every fifteen thousand years or so. The Ancients have records of this class of CME occurring twice before.
SHEPPARD: The ship was very close to the sun when it happened.
McKAY: It’s a massive prominence. It arced up and then collapsed when the magnetic field surrounding it weakened. We’re talking an intense proton stream travelling at over four thousand kilometres per second.
SHEPPARD: Most of the crew was killed instantly but the pilot managed to open up a hyperspace window just as they were hit. He flew the ship back here, jumping ahead of the radiation wave just in time to warn everyone.
McKAY: The Ancients were able to raise the shield and extend it far enough to protect a large portion of the planet from the blast.
WEIR: So what are you telling me? This is going to happen soon?
McKAY: Not soon. It’s happening right now.
(He turns the screen of his laptop towards her. It shows a prominence curling out from the edge of the sun.)
A few points to clear up.

First, the science vessel Adaris was hit by the CME while it was close to the sun. Though most of the crew was killed, some of them survived long enough, like the pilot, to make a quick hyperspace jump back to Atlantis (maybe the jump was also boosted up by the same effects which propelled O'neill, Jacob, the rest of SG-1 and Apophis millions of lightyears away from the Vorash system, during the supernova... but to a minor extent). What's impressive is that the ship wasn't completely destroyed at this point.
It's an impressive feature, for again, a science vessel, especially since the crew was caught off guard.
We may even assert that shields were down, or not necessarily fully active.

Secondly, as we already know, that CME was a proton stream travelling at 4,000 km/s.
Well, stream is a funny word considering that it's much more like a spray than anything else. Or a wave.
This CME is supposed to dwarf anything our sun has emitted.
CONTROL ROOM. The image of the coronal prominence is now on a large screen.
McKAY: The magnetic field around it is already beginning to weaken. When that prominence collapses, the coronal mass ejection will occur. It’ll erupt from a very small area – a mere pinprick in comparison to the total sun’s surface, but it’ll immediately begin to fan out. Within a few million miles, the blast wave will cut a swathe wide enough to take out this entire planet.
SHEPPARD: How much time do we have?
ZELENKA: The prominence will collapse any moment now. After that, we have less than an hour before the radiation wave hits us.
SHEPPARD: Whatever. What are our options?
McKAY: Well, the Ancients were able to raise the shield and stretch it wide enough to protect a significant portion of the planet – attenuated, to be sure, more of a thin bubble, but it was able to block out enough of the radiation ...
ZELENKA: That’s interesting, because we have found evidence of mass extinction on other parts of the planet.
McKAY: Wow! Well, now we know what caused it(!)
WEIR: OK, so our shield is already activated. What else?
McKAY: Ah. Small problem. The Ancients had three ZedPMs at their disposal and we – as you know – only have one. Maybe I was so insistent on keeping them because I too am able to sense trouble on the horizon.
SHEPPARD: Just like a pigeon.
WEIR: So we just need to get the other two ZeePMs back here temporarily ...
McKAY: Not enough time. Look, the Odyssey’s away from Earth. In the time it would take them to return, the blast wave would almost certainly have hit us.
SHEPPARD: How far can we extend the shield with one ZeePM?
ZELENKA: Well, enough to cover the city and perhaps a little bit of the ocean surrounding it, but ...
SHEPPARD: We should evacuate, just to make sure.
McKAY: We can’t gate to Earth. Look, we need the ZedPM’s power for the shields.
SHEPPARD: We’ve got the intergalactic Bridge.
McKAY: The midway station isn’t completed yet. We’d need to ferry people by Jumper. Again, no time.
SHEPPARD: Alright – we’ll send everyone to the Alpha Site and pick ‘em up when this is over.
McKAY: I don’t think you understand. Look, the shield will protect the city from the initial blast, yes, but the entire ecosystem of this planet will be damaged beyond recovery for hundreds of years. Look, we’re talking no plant life, which means no breathable air ...
(Elizabeth faints, dropping to the floor.)
The ecosystem damaged beyond recovery for hundred of years. Yes, that's mass extinction everywhere there's not a shield to block the wave.

So it's, a least, still a total of many hundreds of teratons of energy hitting the parts which aren't even protected.


CONTROL ROOM. Radek is looking at the wall screen which shows that the whales are clustering as close to the city as they can.
ZELENKA: Look at them! Seeking shelter under the umbrella of the city.
McKAY (working on a laptop nearby): No-no-no-no-no-no-no. We don’t have nearly enough power. Look, we can extend the shield twenty kilometres beyond the city, maybe. But it’ll be dangerously thin and there’s no way of knowing whether we can sustain it, especially in a radiation blast of fifty thousand rem.
They're talking about the effects on the planet.
Obviously, he means the dose of radiations at shield altitude, that is, almost sea level, as what a human would get when placed on top of the shield, or located in a spot of the city that wouldn't offer any protection, if the case the shield wasn't up. Say on one of the piers, for example.
The difference between both positions is negligible anyway, since it's only a difference of height which is not meaningful because of how small it is.

If other elements have to be considered, like the figure being relative to a person located under the shield, and even possibly inside the city, then the initial rem would even be ludicrously higher. So let's not go there.

The radiations were likely of the type found in CMEs from our sun. The lantian sun doesn't seem to be different, at least in terms of temperature. Plus it's a yellow star.
Since the rem value is a global indicator, and meant for an average human body, basically the Moon value from 1972 can be directly related to Rodney's example, since they're all humans.
Dismissing the rem values because there would be no human is rather illogical, considering that obviously, any rem value will only be indicated in case humans are concerned.
And humans there were in Atlantis.

But contrarily to Akaviri, I won't use a factor between both rem figures.

Now, this is where it gets really alien to me, but before even attempting big equations, let's lay down the basics.

1 Sv = 100 rem, and 1 Sv = 1 gray = 1 J/kg.
Since Rodney mentionned a dose of 50,000 rems, then I suppose we're talking about 500 J/Kg.
Does get lethal when nearing 5 rem. Above, you're sure as hell to be dead. They would have been 10,000 times deader than dead, if they had been hit.

The average human height is 1.6 m.
"The average weight value for males is between 168 and 183 pounds (76-83 kg). [...] For females, the average weight in adults is 54-64 kg (12-140 pounds). These are considered in the normal range."
1

So let's get an average of all those values to get the approximative weight of some sort of half male half female human.
That's roughly 69.25 Kg.

The Dubois BSA calculator provides, for a human of 69 Kg and a height of 1.6 m, the following BSA:

1.7215 m²

The total amount of joules for such a human would be roughly 69 x 500, thus 34,500 Joules.

________________

Before I continue on this road, without really knowing if it's a correct method, or at least rough enough to get some kind of idea about the powers at play, let me say that there are other elements I don't know what to with, but there really seems to be something at reach. If only we kno whow to compose the puzzle.

There's the radiation weighting factor, I don't know if we need it. It's based on two elements, a quality factor Q, depending on the type of radiations, and another factor N. N was equal to 1 when humans were concerned. It seems to have been ditched out of the meaning of radiation weighting factor.
The stream was composed of protons. They have a corresponding Q factor of 5.

________________

Resuming...

So our hybrid sort of human would have a body surface area of 1.7215 m², and would be throughly infused with 34.5 kilojoues.

Let's try to obtain an intensity there.
It wasn't sure if I had to divide the BSA by two, as it's traditionally done, for example, for spheres life surfaces which only side is facing a source of energy.
It's possible that I should divide it by 2, since the whole body is supposed to be radiated. This would lead to slightly bigger numbers, as the intensity would increase (twice less BSA for the same energy, that's a bigger intensity).

So let's say it's conservative.

I get an intensity of I = 20.04 KJ/m².

Let's use the inverse square law here. I'm not sure about the initial area of the CME there, but we'll at least, get an idea about the initial power.

I'll assume a distance of 1 AU, since all parameters seem relatively similar to the duo Earth - Sol.
1 AU = 150 e6 km

I = P / 4 x pi x r²
P = I x 4 x pi x r²
P = 20040 x 4 x pi x (150 e9)
P = 5666.17651 e24 J (yottajoules)
P = 1354.2487 PT
P = 1.354 ET (exatons).

Surprisingly, they're not too far from Akaviri's calcs when he used the kinetic energies, and he made a couple of assumptions and admitted that the numbers may be one or more orders of magnitude off.

Now, this could be a dose per second.

Other elements I don't get, is just why Akaviri simply didn't make the calc by using Echoes' stream speed of 4000 km/s, instead of a Sol's typical CME speed. There was no reason to limit the calcs to 2000 km/s.
As for Necronlord, I really don't get the point of his attitude, and why he was so hellbent on dismissing the rem figure, and denying the simple pure fact that the frontal arc of the Daedalus' shield did start to glow before it was hit, and kept glowing long after the stream has been deflected... though this is arguing visuals, and at this point, I pretty much ignore them as a whole.
But he was basing his claims on visuals, actually encouraged other people to watch the video as he did, yet did a poor job understanding the most simple phenomenom, up to the point where it was nothing more than trolling.
He also had a problem with the simple fact that Rodney was very worried about the heat, and invented lousy theories to explain why the hull was not being damaged because of extreme heat, especially the parts facing the sun and closer to the point of impact, but were only degrading because of internal heat build do the shields generators generating too much heat around them. Sure man, sure!
He simply invented stuff. At that point, someone needed to post a picture of the front arc glowing and flashing yellow after the stream's gone, to shut his big gapping mouth once and for all.

However, despite the asinine claims, we agree on the idea that the entire planet should have been in the shadow cast by the 304 intercepting the stream (and no, that doesn't mean that the city should have been stuck in a temporary night time, aka an eclipse, since the rest of the sun was not masked from Atlantis by the 304 - how could it be anyway??).

No matter how close to the sun the 304 would have been, it could have never blocked the entirety of the stream to prevent the planet from being partially hit.

Technically, the 304 should have expanded its shield to something as large as the planet itself, to be sure, and this couldn't have been possible, since the Lantians couldn't even protect the facing hemisphere with 3 ZPMS (showing how the shield is very unefficient when it comes to stretching it beyond its naturally designed surface).

See, while the stream is self expanding, obviously, any object placed even inside the stream (it wouldn't block the whole stream) would still cast a cone shaped dead angle, a shadow.
However, when it comes to radiations, it's not a punctual affair. Every square meter of the initial burst will radiate energy omnidirectionally, which means that I can't see how the 304 could have blocked the whole pack of radiations without literally coming with some sort of umbrella as wide as it would need to be to stretched edge to edge to the truncaturated cone formed by the edges of Earth (facing diameter being the smaller base, the tip of the cut cone) to the edge of the hyperactive spot at the surface of the photosphere (the largest cone's base, which diameter is that of the assumedly circular sun spot).

Now, if someone finds a way to explain how the stream remained that tight... from absurdingly powerful magnetic fields to some kind of black hole corridor that guided the stream, or a corridor of particles which managed to "tug" the super energized ions...

There's just no way a CME that already starts as wide as a planet, can shrink to the size of a 304... or there's some kind of weird phenomenom where there particles are pulling themselves towards each other, despite the energy and expected expansion... and then I wonder how such a thing could technically burst...

The site lists all SOHO spotted CMEs.

Some of them have angular width of two degrees, but they're rare.

It's simply way faster to claim that it's the result of some magical power, and that this CME is nothing natural, but triggered by something that's inside the sun, or some entity. Something.

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Post by Mr. Oragahn » Sat Jun 30, 2007 3:47 pm

I consider those exaton figures particularily reliable and in touch with the reality of the dialogue.

Using the kinetic energy from the stream gives exatons of energy. Using the rems as a basis leads to an exaton range.

The dialogue suggest that the stream would still be exceptionally narrow. We have to assume a very tight super CME here.

The SOHO CME search engine reports a very few CME with an angular width of 2 degrees. Unsurprisingly, they're the CMEs with either the highest accelerations or the highest linear speeds.

According to the dialogue, they were planning to place themselves suicidally close to the sun, below a few million miles from the sun, before the CME could fan out too much.

Let's start by assuming that at the point of interception, the stream would be as wide as Earth.

So let's pretend that by the time the stream hits the Daedalus, it is as wide as Earth. We're talking about a disc perpendicular to the stream. With a radius of 6,372.797 km, and a total energy of 1.354 e15 KT, we get the following intensity:

I = 10.612278 KT/m².

We know that a 304's shield is egg shapped. So basically, the more slope the edge of the shield, the less opposition it will put against the stream. That's why we have to focus on an area of the shield that's flat enough, for a conservative purpose. We assume that at least the one square meter at the frontal tip of the shield will be relatively flat, and oppose most of the resistance.

Always ditching visuals, but paying attention to dialogue, we see that even a ZPM boosted asgard shield had troubles withstanding the level of energy, both kinetic and thermal.

We've seen an unboosted 304 shielding resist to much higher levels of punishment than that. For example, Wraith cannons, ranging in the gigatons (Misbegotten puts a minimal cap of several hundreds of kilotons to megatons level shots). That's not even counting the more exotic ZPM draining weapons.

It would be completely absurd to think, then, that an advanced shield backed up by a fresh ZPM could barely handle a megatons of energy.
Megatons because the bombardment lasted *some* time.
We should also multiply the intensity by the forward shield arc surface - at least as far as radiations are concerned, since most of the KE would be deflected.

Say, now, that the stream was as wide as our moon, when it hit the Daedalus.

A radius of 1,737.103 km.

The intensity is:

I = 142.8294 KT/m².

Again, it seems totally absurd that the shield couldn't handle this, while it faces weapons far more powerful.

- On the same, please notice that the limited efficiency could also be due to the asgard shield itself, not fully, nor properly, exploiting the ZPM's power. But there's a limit to which we can push that reasoning -

In reality, and still only going by dialogue, not much time passed between the moment the prominence collapsed and the ship was hit:
McKAY: Oh no.
SHEPPARD: What?
McKAY: The prominence is fully collapsing into the photosphere. Brace yourselves.
(He grabs his tablet and starts working on it. On the sun’s surface, the emission bursts out and heads into space. John stares.)
SHEPPARD: Rodney?
McKAY: ZedPM is online.
(The emission heads towards Daedalus and impacts its shields, which deflect it away in all directions. Caldwell squints as the bright light envelops the shields and the ship vibrates under the strain.)
CALDWELL: How long will this last, Doctor?
McKAY: Anywhere from a few seconds to several hours.
SHEPPARD: Hours?! You never said anything about hours!
CALDWELL: We’re building up serious heat behind the shield.
McKAY (plaintively): I told you this wasn’t a good plan!
At a speed of 4000 km/s, they clearly were at less than a sun radius from the photosphere (for reference, Sol has a mean diameter of 1.392 e9 m).

Now, let's get the other extreme. Let's try to know the width of the CME when it leaves the photosphere.

"The width of a CME is measured as the angle subtended by the outer edges of the CME at the Sun center."
Page 18, The Sun and the Heliosphere as an Integrated System.

So assuming the narrower CME possible, we'll work with an angular width of 2 degrees, and work from the assumption that the lantian sun is similar to ours.

Sol mean radius: 0.696 e9 m
Theta = 1°

Let's get an hemisphere surface area here:

A = 2 x pi x r x r(1 - cos (theta))
A = 463.5 e12 m²

So intensity is:

I = 2.921 KT/m².

Here, we can see that there's definitively an issue, as even the intial cross section surface area of the stream is already wider than when using Earth's and Moon's parameters. That was to be expected.

I've read a bit more on the super CME analyzed in the PDF. It is described as having an angular width or 5 arcmin. It is even tighter than a 2 degree angular width (1 arcmin = 1/60 degree).
It makes for an initial very tight spot... but still very large. Too large.

"11.1 CME Initiation

Even after three decades of CME observations, we do not fully understand how CMEs are initiated. We do understand the details of the pre-CME structure: a set of one or more closed flux systems that eventually erupt. This could be a simple bipole with a core-envelope structure (Moore et al., 2001; Magara and Longcope, 2001), a flux rope with overlying restraining field (Low and Zhang, 2002; Forbes et al., 1994; Linker et al., 2001; Wu et al., 2000), a combination of bipoles (Machado et al., 1988) or multipolar structure (Antiochus et al., 1999; Chen and Shibata, 2000; Feynman and Martin, 1995). A successful CME model should account for the observed range of speed, mass, acceleration of CMEs, and the distribution of energy into heating, particle acceleration and mass motion. The current level of sophistication of CME models is less than adequate to account for all the observed characteristics (see e.g., Forbes, 2000; Klimchuk, 2000). Initial models based on the assumption of flareproduced CMEs (e.g., Dryer, 1982) have largely been abandoned because CME onset precedes flare onset (e.g., Wagner et al., 1981). After this, the emphasis shifted to loss of equilibrium (Low, 1996), primarily motivated by the three-part structure (frontal structure, cavity, and core) of CMEs and the coronal helmet streamers well observed in eclipse pictures (Saito and Tandberg-Hanssen, 1973). The cavity is identified as a flux rope of low plasma density and high magnetic field strength. In the pre-eruption state, the flux rope is held down by the prominence mass, the mass of the plasma contained in the overlying fields, and the magnetic pressure of these overlying fields. A CME is produced when the confinement of the flux ropes breaks down for a variety of reasons, such as loss of prominence mass (Low and Zhang, 2002). The interaction between the current in the flux rope and in the current sheets in the overall configuration decides the eruption and dynamics of the flux rope. This way, it is even possible to account for the accelerating CMEs from inverse polarity prominences and the constant speed CMEs from normal polarity prominences. It is currently believed that the energy required to propel the CME has to come from the magnetic fields of the solar source region (see, e.g., Forbes, 2000). To illustrate the maximum energy that may be needed in CMEs, let us consider the 2003 November 04 CME, the fastest (~2700 km/s) event of cycle 23 (see Fig. 12): The CME had a mass of ~2×10^16g, so that we can estimate the kinetic energy to be ~7×10^32 erg. There is probably no other CME with an energy larger than this, so we can take that the largest energy released from an eruption is ~10^33 erg, and might represent the maximum free energy in the magnetic fields of the source. Considering a large active region (photospheric diameter ~5 arcmin), we can estimate its coronal volume of 10^30 cm3. An average coronal field of 200 G over this volume implies a magnetic potential energy of ~10^33 erg. Microwave observations of the corona above sunspots have shown magnetic fields exceeding 1800 G (White et al., 1991), so an average of 200 G is not unreasonable. The highest value of potential magnetic energy in active regions surveyed by Venkatakrishnan and Ravindra (2003) is also ~10^33 erg. Since the potential magnetic energy is probably smaller than the total magnetic energy by only a factor <2 (Forbes, 2000), we infer that occasionally a substantial fraction of the energy contained in an active region may be released in the form of a CME. How this much free energy builds up in active regions is not fully understood."


Pages 45 & 46, The Sun and the Heliosphere as an Integrated System.

It is largely defined, here and there in the document, that the vast bulk of the energy is kinetic in nature. A shockwave is created, due to the immense acceleration of the stream's matter.
Eventually, we could pretend that this close to the sun, the stream got caught inside another magnetic field.

Could have the stream been that tight?

Though I consider that the visuals are still wrong, maybe the size of the stream could be explained by the presence of an abnormal magnetic field, recreating a rope flux and thus focusing the stream while still within close proximity to the sun.
Then, where the visuals would be wrong would be in depicting the Daedalus as being so far from the sun (just as much as makin the plasma look like globs of popcorn once deflected, but that's not here nor there).
When you think about it, they were supposed to be suicidally close to the sun, yet they were clearly not. We've seen freaking Death Gliders even fly at closer ranges, without a problem.

But wouldn't hot gas pan out? Yes, but we can reduce this effect by reducing the gas' temperature. That said, it won't be easy. It was yellow-white.
But let's pretend that on those 10^33 ergs (e27 joules, almost 1 exaton) worth of magnetic fields which accelerate particles, a small percentage of this "power" actually tightens the matter stream instead of accelerating it.
Technically, a cold gas would barely expand. It could be propelled as a stream straight forward, and be maintained tight by a relatively weak perpendicular magnetic field.
Now, the gas here is damn hot, but I guess that when you have a field worth of hundreds of petatons to propel particles, I suppose that a small amount of this field could be argued to be perpendicular to the stream's vector as well, and thus provide kiloton or megaton level worth of "compression", especially when the super CME from "Echoes" is much more powerful.

But why would the ship's shields suffer from thermal damage?

Well, first, there could be friction. If shields in Stargate emulate a form of solid shell, it would explain that a friction with high velocity particles would heat up the shield.
Another possibility would be that the shield is extremely weakened by the high amount of kinetic energy, and thus lets low amounts of heat pass through.

Some would say this wouldn't explain how the hull could suffer from thermal damage.
Fact is, the shield isn't 100% efficient. No shield could be, really. At these levels of energy, even 0.0001% of leeway (arbitrary value) would let an important amount of kinetic energy pass through.

See, for example, that when hull plates are pealed off, they actually fly backwards, like if the ship was flying through a tempest, against the wind.
That alone would prove that a small portion of the stream was passing through. And this would create friction on the hull.

Globally, there are still several inconsistencies, but the event itself is very spectacular by essence, and above all, it might be made more or less legit if the sun had something special. It must have, anyway, considering the exceptional power of the CME.

In the end, this would mean that the ZPM really had to cope with a large portion of that stream's kinetic energy, since the shield possess a zone on its forward hemisphere where it's almost flat, and thus acts as a wall against that stream.

Now, this requires a bit more clarifications.

First, if the ship had been close to the sun, the shields would have had to deal with the star's default radiations, even before thinking about the CME.

Secondly, for the stream to be that powerful and narrow, it would need to be intercepted while being inside the magnetic field. This means that the ship would be in that field as well... and thus countering, with her engines, the repulsion of the field... and the kinetic energy it's facing.
Maybe the shield can lessen the effects of the magnetic field, no matter how powerful it is, but I doubt it. So we're almost looking at a thrust being twice the amount of "pressure" that pushes it backwards.
Thus pushing forward with thrust levels worth of several hundreds, if not thousands of petatons. But see, even with a ZPM, I have issues believing that even the engines could support that. This number could be reduced if the Daedalus had mass lightening tech, but it doesn't seem to be the case.
It can also be reduced since the field is accelerating the stream over time, between eight minutes to maybe one hour, so the engines wouldn't need to output this amount of energy within one or two seconds, but within at least 480 seconds, so that helps to reduce the wattage to the low petaton/high teraton range, for eight minutes, and mid teraton range for more than 16 minutes.
More likely, shields are often shown making a large portion of the KE resulting from bombardment "go somewhere". We should then assume that this effect was amplified with the ZPM.

In a way or another, the ZPM would have been drained far above what was solely needed to deflect the (portion of the) CME.

Now that's just fancy talk, hehe, cause I don't know where I'm really going with all that stuff. :)

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