Can a powerful CME cause a comet to fragment?

[NEOWatcher]

I followed this link to Deep Impact results which seem to contradict the notion of a dirty snowball.

Please explain what seems to contradict that notion. I don't see it.

Here's what I do see in the results section of the wiki article.

A total of 5 million kilograms (11 million pounds) of water and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact

Just because they got less than expected doesn not mean it's contradictory.
20% to 50%

Furthermore, I guess Donald Brownlee, head of NASA’s stardust mission, also expressed a non-mainstream idea when he stated, “It’s a mystery to me how comets work at all.” So it appears to me the mainstream ideas aren't satisfactory to even those with the most knowledge about how comets are supposed to work and would be threatened with excommunication for making such a comment since we all know Wikipedia explains exactly how comets work.

Sorry; but that link requires a subscription. I looked for that quote with google, there were plenty of hits. Unfortunately they were all on discussion boards related to vastly non-mainstream sites, and most of them had to do with the electric universe.
So; my suspicion at this point is that the comment was taken out of context. I've heard plenty of scientists refer to "mystery" when they are trying to decide among various options and not because there are no options.

So when scientists start telling me, "Hey trust us....those ices we've theorized, but can't find, are really there....they're just hidden....trust us on this" it immediately triggers my ** detector. Science is based on evidence not trust. So show me the evidence.

What's wrong with the results from deep impact.

[captain swoop]

Gdaniels99
Do not argue Moderation in thread. If you have a problem with any post or with any Moderation then report the post or PM a Mod.
Any more and you will be Infracted.

This forum is for asking Questions and getting Mainstream answers.
If you have any problems with an answer or don't understand then ask more questions.
If you don't like the answers and insist that some idea you have or some non mainstream theory is the way to go then you start a thread in the gainst the Mainstream forum where you can advocate anything you want.

Mainstream is the mainstream beacuse it is accepted by the Mainstream of science, it has been advocated and has support and evidence.
It is not for those giving the mainstream answers to keep posting all the evidence and support for the mainstream position, this is available elsewhere in papers, Journals, College Libraries and Textbooks.

If you have any problems with any of this then report this post or PM one of the mods

[gdaniels99]

Temple1 has craters that must have been formed by relative large impacts, given the small effect of the Deep Impact. How would a body that sturdy get pulled apart by the very slight gradient of Jupiter's gravity?

I'm waiting for an answer to this one too. Can't wait to see what type of mental gymnastics people will go through to make this fit into the "loose conglomeration of ices and rocks" theory of comets.

[captain swoop]

gdaniels99
I will be generous and think that your post and mine crossed over and you never saw it before you posted again.

Ask questions and get mainstream answers. IF you don't like them then take it up elsewhere.

[gdaniels99]

gdaniels99
I will be generous and think that your post and mine crossed over and you never saw it before you posted again.

Ask questions and get mainstream answers. IF you don't like them then take it up elsewhere.

Yep, that's what happened. But I still would like someone to respond to the peer review journal article I posted about the solar wind as a possible cause of comet flare ups. That was the whole reason I restarted this thread and so far it has been ignored. Has the article been debunked? Has other evidence invalidated the data in the article? It doesn't seem like "fringe" science which is why I posted it in this thread. But it does seem to suggest more than just solar heat is responsible for flare ups so I was hoping to get some kind of commentary or reaction from the experts on this article.

[spjung]

I'm not advocating anythingFurthermore, I guess Donald Brownlee, head of NASA’s stardust mission, also expressed a non-mainstream idea when he stated, “It’s a mystery to me how comets work at all.” So it appears to me the mainstream ideas aren't satisfactory to even those with the most knowledge about how comets are supposed to work and would be threatened with excommunication for making such a comment since we all know Wikipedia explains exactly how comets work. He should just read up and educate himself!

Sorry; but that link requires a subscription. I looked for that quote with google, there were plenty of hits. Unfortunately they were all on discussion boards related to vastly non-mainstream sites, and most of them had to do with the electric universe.
So; my suspicion at this point is that the comment was taken out of context. I've heard plenty of scientists refer to "mystery" when they are trying to decide among various options and not because there are no options.

I read the article. It's from 2005, published a few months after the Deep Impact impactor hit 9P/Tempel. Brownlee was referring to how warming doesn't seem to effect the whole surface of a comet evenly, instead activity is confined to jets. In addition, the Stardust mission saw jets of material on the dark side of Wild 2. The hypothesis was that the heat from the outside of the comet heats the interior. As far as the craters as concerned, Brownlee thought that they may be from explosions, not impact. Light penetrates the surface of the comet and heats a portion beneath. Like a popcorn kernel, the pressure builds up until it explodes outward.

[NEOWatcher]

That was the whole reason I restarted this thread and so far it has been ignored. Has the article been debunked? Has other evidence invalidated the data in the article?

I think it's reasonable to ask what the mainstream view of the article is, but the question has been muddied by some other statements.
Particularly, statements about the makeup of a comet and the normal outgassing of it.
It's hard to get to the paper when there seems to be some misconceptions in the discussion surrounding it. We need to resolve those first.

[NEOWatcher]

I read the article...

Thank you for summarizing it.
So if I'm reading it right (in context of this thread) it's a matter of how the heating occurs and its affect on the comet rather than if it's heating in the first place.
Pretty much what I suspected.

[tusenfem]

Yep, that's what happened. But I still would like someone to respond to the peer review journal article I posted about the solar wind as a possible cause of comet flare ups. That was the whole reason I restarted this thread and so far it has been ignored. Has the article been debunked? Has other evidence invalidated the data in the article? It doesn't seem like "fringe" science which is why I posted it in this thread. But it does seem to suggest more than just solar heat is responsible for flare ups so I was hoping to get some kind of commentary or reaction from the experts on this article.

As I already wrote before, the interaction of the solar wind with the comet can do all kinds of things. The surface of a comet is expected to be full of dust, which will be blown out if an outgassing vent is located near it. The paper that you linked to is telling:

It is well known that when a comet is moving towards (or from) the sun sharp fluctuations in its brightness (i.e. comet outbursts, as well as less significant variations of intergral brightness) are often observed on the background of a uniform change in the comet brightness. The observed correlation with solar activity and the existence of a 27-day recurrencs of comet outbursts made it possible to conclude that comet outburst activity is related to the solar wind.

So, there is the regular expected change in the brightness of the comet which comes from the normal development, that means the heating of the surface by the sun. And then there are the outbursts which may be created by the solar wind, by an interaction with a shock wave as in the paper by Ptitsyna et al.

And on page 167 interestingly the same conclusion is arrived at as I wrote down lots of posts ago:

An early mechanism connecting the comet outbursts with interplanetary shock waves is duggested in Eviator et al. (1970). The intperpanetary shock waves generated by solar bursts are considered to be an agent in transmitting the energy necessary for a comet dust cloud disturbance. The increase in comet brightness occurs according to this model due to the fact that in the vicinity of a dense cloud high albedo Plass particles appear, wich are accelerated to hih velocities during their interaction with the shock front, and reach distances of about several thousand kilometers from the core, thus increasing thecomet's reflecting capacity and consequently its brightness.

This was my unedumacated guess lots of post ago for these outbursts.
Then they continue that solar outbursts are not the way to go, but that the velocity waves and shock waves generated are the way to go to these outbursts. But note this has all to do with DUST and not with GAS. The outgassing of the comet is AFAIK only caused by solar irradiation.

[gdaniels99]

So; my suspicion at this point is that the comment was taken out of context.

And your evidence for this is? So here's a portion of the article that one can read without a subscription:

"The Deep Impact team had hoped that, when the impactor spacecraft hit Tempel 1, it would kick up a relatively small cloud of dust, expose an area of pristine icy material underneath, and instigate some spectacular jet activity. This is exactly what didn't happen. The dust cloud was more than 10 times bigger than expected, and the effect on Tempel 1's activity was almost nil.

We have now had four close encounters with comets, and every one of them has thrown astronomers onto their back foot."

So just based on the introductory paragraph free to non-subscribers I would think a comment such as "“It’s a mystery to me how comets work at all” is completely consistent with the tone of the article. But instead you cite the fact that it's quoted on various other "fringe" websites as supporting evidence for your contention that it was taken out of context??????? So here's the full quote from the article and its context:

Prior to the European Space Agency’s Giotto mission to study Halley’s comet in 1985, for example, astronomers believed that as sunlight fell onto a comet, its spin would mean that the heat evaporates a more or less even layer, revealing more icy material beneath. Giotto showed that this idea was hopelessly simplistic. “As soon as we saw the nucleus it was clear that activity was confined to individual jets and not coming from the whole surface,” says Giotto project scientist Gerhard Schwehm of the European Space Agency. In fact, only 15 per cent of Halley’s total surface area was expelling material at the time of the fly-by. The observation has shown astronomers that they are in the dark about even the basics. “We still do not know what drives comet activity,” says Schwehm.

Donald Brownlee of the University of Washington in Seattle goes further. “It’s a mystery to me how comets work at all,” he says. Brownlee has good reason to make this claim. He is the principal investigator on NASA’s Stardust mission, which flew past comet Wild 2 on 2 January 2004. The fly-by images showed 20 active jets spread across the comet’s sunlit side. So far, so good. Then they saw something that added a new twist to the mystery. Two of the jets were on the night side of the comet.

Astronomers had expected that the jets would simply turn off when the comet turned them away from the warming rays of the sun. For Brownlee it seems to be pointing to an inescapable conclusion. “I think that some process is allowing heat to get down below the surface of a comet and drive the activity from the inside out,” he says.

The clue might be in the dark surface layers of the comets. Though it is hardly what you would expect of icy bodies, the exteriors of both Halley and Wild 2 are as black as coal, and these dark layers absorb heat. At the time of the Stardust encounter, when the comet was almost twice as far away from the sun as the Earth, the surface of Wild 2 was a comfortable 18°C. Its interior would have been much colder, well below 0°C in fact, so heat would naturally flow inwards. That’s as far as the explanation goes at present. “I have no idea about the details of the process,” Brownlee admits."

So what I take away from this article is that there is NO "mainstream" theory about what a comet is....just a bunch of speculations and hypotheses...nothing even approaching the level of a theory according to this definition of theory:

In science, a theory is a well-substantiated, unifying explanation for a set of verified, proven hypotheses. As opposed to theory, a hypothesis needs to be testable and falsifiable.

[gdaniels99]

this has all to do with DUST and not with GAS. The outgassing of the comet is AFAIK only caused by solar irradiation.

I understand this point. Really I do. Even the solar wind argument claims the brightenings are due to some type of electrostatic charging (and levitation) of the dust particles. But a dust storm isn't going to cause a comet to fragment. Which is why I then posted links to the Comet Holmes outburst which showed fragments flying off of it at 280mph! No electrostatic dust storm is going to cause such a thing.

So is your contention that Comet Holmes outburst was purely dust related, no gases involved? If so, what would explain the fragments exiting the comet at 280mph?

[NEOWatcher]

And your evidence for this is?
[...]But instead you cite the fact that it's quoted on various other "fringe" websites as supporting evidence for your contention that it was taken out of context???????

Did you not understand my post?

I said clearly and plainly "suspicion". That is no asserting anything that requires evidence. It is an opinion. On top of that, I explained my reasoning how I came to that suspicion.

So what I take away from this article is that there is NO "mainstream" theory about what a comet is....just a bunch of speculations and hypotheses...nothing even approaching the level of a theory according to this definition of theory:

And speculations and hypotheses that will lead to a theory. I can live with the fact that we are pitting hypothesis against hypothosis. And; I don't have enough detail to really say what is more probable than the other (which is what science is about).

What I am concerned about is your claim that comets are not dirty snowballs and that there's no evidence...

So when scientists start telling me, "Hey trust us....those ices we've theorized, but can't find, are really there....they're just hidden....trust us on this" it immediately triggers my ** detector. Science is based on evidence not trust. So show me the evidence.

... You make no acknowledgment that the evidence for ice is there.

And your "** Detector", how is that any different than my "suspicion"?

[gdaniels99]

I think I should ask the question this way:

Can charged particles interact with (frozen) gases under pressure in such a way as to cause an explosion? Which types of particles interacting with what types of (frozen) gases under pressure could cause an explosion?

[gdaniels99]

I think I should ask the question this way:

Can charged particles interact with (frozen) gases under pressure in such a way as to cause an explosion? Which types of particles interacting with what types of (frozen) gases under pressure could cause an explosion?

Here are some research papers which might apply but I can't get access to read them:

"Secondary ions produced from gaseous and frozen H2O under energetic (MeV/amu) Ar ion impact"
"Oxygen Outgassing Caused by Electron Bombardment of Glass"

[tusenfem]

Here are some research papers which might apply but I can't get access to read them:

"Secondary ions produced from gaseous and frozen H2O under energetic (MeV/amu) Ar ion impact"
"Oxygen Outgassing Caused by Electron Bombardment of Glass"

I don't see that the first paper is related to comet, it is energetic ions impacting ice and gaseous water. The latter may occur in the coma of a comet, the former will probably not take place as we know that the water ice is under the surface.

The second paper is something you just looked up and does not seem to have any relevance to comets, it is bombardment of GLASS.

Ionized gasses or plasmas interact with the icy surface, e.g. at the Galilean moons at Jupiter, and the result is sputterings, that is the knocking off of particles (molecules) off the surface of the moons. These can be ionized then. There is no way that this can lead to an explosion. So the answer is no.

The brightening of the comet can only come from increased dust reflection, as described in the paper that you linked to yourself.
The breaking up can be caused by tidal forces, as happened with Levi-Shoemaker at Jupiter. Not alll comets are the same, some will be a large rock some wiill be an agglomoration of smaller pieces which are easier to break up.

[gdaniels99]

The breaking up can be caused by tidal forces

What tidal forces broke off those pieces from Comet Holmes and caused them to eject at 280mph????? 17P/Holmes was far from Jupiter and the Sun at the time of the outbursts.

[Reality Check]

I'm waiting for an answer to this one too. Can't wait to see what type of mental gymnastics people will go through to make this fit into the "loose conglomeration of ices and rocks" theory of comets.

Firstly Jupiter's gravity does not have a "very slight gradient" as in TooMany's post. It has the second steepest gradient in the Solar System (the first being the Sun of course). Comets approaching the Sun can fragments so it is not surprising that comets approaching Jupiter can also fragment.
Secondly, no "loose conglomeration of ices and rocks" theory of comets exists. Comets are dust and ice that are gravitationally and perhaps chemically bound ("loosely" if you like). It is the weakness of the binding that allows comets to fragment.
Thirdly, all comets are not identical to Temple1. Comets ahave a variety of sizes and densities. Temple1 seems to be an outlier with more dust than other comets. So using Temple1 as an example was not a good idea.

[Reality Check]

So what I take away from this article is that there is NO "mainstream" theory about what a comet is....just a bunch of speculations and hypotheses...nothing even approaching the level of a theory according to this definition of theory:

What you should take away from that article is that even science reporters can concentrate on what is newsworthy, not the actual science.

There has been a mainstream scientific theory about what a comet is for decades. Like all scientific theories it changes to match empirical data like
* The Giotto mission in 1985 showed that outgassing was concentrated in jets rather then spread across the surface. Guess what - jets have been part of the mainstream theory since ... 1985!
* The jets can also appear on the night-side of comets and there is an explanation: "The clue might be in the dark surface layers of the comets ...".

[Reality Check]

What tidal forces broke off those pieces from Comet Holmes and caused them to eject at 280mph????? 17P/Holmes was far from Jupiter and the Sun at the time of the outbursts.

Where in tusenfem's post does he state that tidal forces caused Comet Holmes outburst ?????
The explanations I have seen for the Comet Holmes 2007 outburst do not mention tidal forces.

When comets get close enough to a massive body then tidal forces can fragment them, as happened with Levi-Shoemaker at Jupiter.

[Shaula]

What tidal forces broke off those pieces from Comet Holmes and caused them to eject at 280mph????? 17P/Holmes was far from Jupiter and the Sun at the time of the outbursts.

There are two or three possibilities on the Commet Holmes Wikipedia page with links to the papers that support 2 of them. None of them are tidal. All 3 are consistent with what was observed and do not require new physics.

[tusenfem]

What tidal forces broke off those pieces from Comet Holmes and caused them to eject at 280mph????? 17P/Holmes was far from Jupiter and the Sun at the time of the outbursts.

I am getting confused here about your assertions. In your OP you tell us that:

For instance, I know CME's can cause extreme outgassing of a comet like Comet Holmes in 2007. And I've also seen NASA footage of a CME ripping off the plasma tail of Comet Encke:

http://www.nasa.gov/mission_pages/st...ews/encke.html

But could it actually cause a comet to break apart or at least break a large fragment off? If so, how large of a CME would be required to break a fragment off of a comet like Encke?

The "outgassing" is already discussed and the flare up is created by dust and not by outgassing.
Here your question is can pieces be broken off.

Comet Holmes lost its tail, which is a result of magnetic reconnection in the tail, not of a piece breaking off.

Then there is the eruption of comet Holmes from the space.com link which says:

It has since dimmed somewhat as the material races outward from the nucleus at roughly 1,100 mph (0.5 km/sec).

The Hawaiian astronomy team writes in a press statement: "This amazing eruption of the comet is produced by dust ejected from a tiny solid nucleus made of ice and rock, only 3.6 kilometers (roughly 2.2 miles) in diameter."

That 0.5 km/s is the dust leaving the comet, as the comet is so small, its gravity cannot hold on to it. Through various interactions it will be "left behind" along the path of the comet. And again it is dust here, not a breakup of the comet.

Then in the end it comes with:

The offset nature of the coma, seen in ground-based images, suggests "a large fragment broke off and subsequently disintegrated into tiny dust particles after moving away from the main nucleus,"

Now, the problem here is the "offset nature of the coma" which is mentioned here for the first time in the last sentence. So I have no idea what they mean here (another good job of a terrible press release, scientists please READ what you send out) And that offset is possibly created by a piece breaking off, or-like-whatever.

Then there is the sciencedaily link which says:

While cometary outbursts are common, their causes are unknown. One possibility is that internal pressure built up as the comet moved closer to the Sun and sub-surface ices evaporated.

The pressure eventually became too great and part of the surface broke away, releasing a huge cloud of dust and gas, as well as larger fragments.

Well, seems rather clear what the research team thinks the cause can be.
As again the gravity of the comet is small and there is little to impede the possible ejected fragments there is no problem whatsoever why these pieces would not travel at high velocity, compare it with a bullet shot from a air pressure gun, or with boulders shot from an exploding volcano.

[spjung]

Thank you for summarizing it.
So if I'm reading it right (in context of this thread) it's a matter of how the heating occurs and its affect on the comet rather than if it's heating in the first place.
Pretty much what I suspected.

Yes, that's pretty much it.

Astronomers had expected that the jets [of Wild 2] would simply turn off when the comet turned them away from the warming rays of the sun. For Brownlee it seems to be pointing to an inescapable conclusion. "I think that some process is allowing heat to get down below the surface of a comet and drive the activity from the inside out," he says.

The article goes on to say how dark and warm (18 °C) the surface of Wild 2 was when Stardust was there.

[TooMany]

There has been a mainstream scientific theory about what a comet is for decades. Like all scientific theories it changes to match empirical data like
* The Giotto mission in 1985 showed that outgassing was concentrated in jets rather then spread across the surface. Guess what - jets have been part of the mainstream theory since ... 1985!

Yes, there was a mainstream theory in 1985 and it was not correct. That has been admitted by plenty of mainstream scientist. Comets may be more like hard dirt balls with some frozen volatiles. In any case, Temple1 is not loosely bound as say an aggregate of dry snow flakes and dust held together by gravity alone.

This is pure speculation, maybe it's impossible. Perhaps the explanation of these violent outbursts and fragmentation is that there are more volatile gases in liquid or solid form below the comet's insulating surface. I'm thinking of O2, H2, N2. When sufficient heat reaches this condensed gas, it results in much more powerful out gassing than can be expected from sublimation of water ice. I know H and O are seen in the tails, but this is usually attributed to photo dissociation of water. Such volatiles would aid in creating internal stresses that assist fragmentation. Also, with fragmentation, one might expect an large increase in out gassing of the pieces (more per unit area).

Tidal forces can also heat the interior (like Io) which could aid in the breakup.

Regardless of the negligible gravity, there are significant molecular forces holding things together. Imagine you make a dirty snowball and compress the air out of it and cover it with coal dust. Then you toss it out the portal of the space station. What do we expect to happen to it? Will it act like a micro comet? Will it ever fragment?

[Hornblower]

I can accept the possibility that the additional heat from a powerful CME could have been the straw that broke the camel's back in the sense of hastening an eruption that was about to happen a short time later in the absence of the CME.

[TooMany]

I can accept the possibility that the additional heat from a powerful CME could have been the straw that broke the camel's back in the sense of hastening an eruption that was about to happen a short time later in the absence of the CME.

Do you have some idea what the power density and duration of a CME might be, as compared to the normal solar flux? Apparently there is enough associated penetrating radiation to be a danger to astronauts. Is it possible that the penetrating radiation causes heating below the comet's surface where volitiles remain?

[TooMany]

Secondly, no "loose conglomeration of ices and rocks" theory of comets exists.

You mean not anymore, right?

[TooMany]

As again the gravity of the comet is small and there is little to impede the possible ejected fragments there is no problem whatsoever why these pieces would not travel at high velocity, compare it with a bullet shot from a air pressure gun, or with boulders shot from an exploding volcano.

There may be negligible gravity, but masses are accelerated and that takes some energy. What powers this gun? One speculation seems to be that the crust is a seal which can burst from the vapor pressure of underlying sublimating water.

[TooMany]

As far as the craters as concerned, Brownlee thought that they may be from explosions, not impact.

Have a look at these photos of comets. These are not impact craters?

[gdaniels99]

So, I decided to read some eye witness accounts of the largest solar flare/CME in recorded history: the 1859 Carrington Event. I was curious to see if any comet fragments (meteors) might have been also associated with this event. I wasn't disappointed:

“…a brilliant meteor was seen to shoot through the sky…and when near the horizon, burst like a rocket. Almost immediately afterwards the rays of an aurora Australis were most brilliantly visible in the N.E.”

“A very brilliant meteor was seen towards the south, which fell in a curve from about 45 deg. elevation, standing to the eastward. Almost immediately following this the glancing rays of a vivid aurora shot up the sky, at first more fully developed to the west, but afterwards stretching across the whole of the south from the hills to the sea.”

http://ntrs.nasa.gov/archive/nasa/ca...2005210155.pdf

I'm sure this is purely coincidental.

[Reality Check]

You mean not anymore, right?

I mean not ever AFAIK. The papers that I have read about comets say dust not rocks.