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GlennLeDrew
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Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6225074 - 11/30/13 12:15 PM

When postulating multiple nuclear fragments, consider the image scale/resolution, the distance to the comet, and the time since potential break up. A ~2km body which breaks up will have its parts separate at a very leisurely pace. If we suppose a velocity range of, say, 10m/s (which might be on the fast side), that's 864 km/day. These images resolve to what, 10,000 km/pixel (and probably worse) at the solar distance? It would take some time for discrete bits to be separately resolved in such images. Moreover, tidal disruption tends to spread the particles into a string oriented pretty much along the orbit, and not in a randomly scattered grouping.

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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6225095 - 11/30/13 12:25 PM

Quote:

I am not certain if this is noise or a star, but the latest C3 shows a bright speck that was not present in previous frames.

And it's in the corresponding vicinity where the nucleus should be, on ISON.



Not visible in the "latest" image (dated 2013/11/30 15:54, presumably UTC). Just a faint smear without any indication of strong condensation. The wraith of the tail IMHO.

As others have pointed out, the raw images are inherently very noisy. Any true nucleus is not likely to be visible but if there was a well defined inner coma, it should be present in consecutive frames and be moving along the predicted path of the comet as seen from the camera's location.


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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: GlennLeDrew]
      #6225133 - 11/30/13 12:44 PM

Quote:

When postulating multiple nuclear fragments, consider the image scale/resolution, the distance to the comet, and the time since potential break up. A ~2km body which breaks up will have its parts separate at a very leisurely pace. If we suppose a velocity range of, say, 10m/s (which might be on the fast side), that's 864 km/day. These images resolve to what, 10,000 km/pixel (and probably worse) at the solar distance? It would take some time for discrete bits to be separately resolved in such images. Moreover, tidal disruption tends to spread the particles into a string oriented pretty much along the orbit, and not in a randomly scattered grouping.



Yeah ... the initial seperation speed would be largely the result of the rotational motion of the nucleus before it fragmented. A 2 km body rotating in hours doesn't have much to impart in the way of differential velocity when it fragments.

The remnant visible today (Nov 30) seems to be pretty well differentiated in a way which is consistent with almost total disintegration of the nucleus i.e. there is nothing of any significant size left. Also the remnant is enlarging and continuing to grow fainter in terms of surface area in a way which seems to be consistent with radiation pressure sorting & dispersing dust grains together with increasing solar distance reducing illumination. There may be a few boulder sized objects but there is no hope of detecting these individually at this distance. As these would have to be quite resistant to heat to survive ablation during perihelion passage these would most likely need to be metallic (iron) ... but there doesn't seem to be any way in which kilometere size range Oort cloud objects could accumulate metallic lumps, iron would be accreted as particles & there wouldn't be significant melting of stony or metallic particles during the accretion process for an object in this size range. So my opinion is that there probably isn't very much left at scales bigger than gravel or even sand.


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MessiToM
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Re: Comet ISON - Cooked well done? new [Re: brianb11213]
      #6225214 - 11/30/13 01:34 PM

I really hate to agree with you ^ because I so badly wanted this to put on a show in the dawn sky but it genuinely does look broke up and spread out now.

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nodalpoint
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Re: Comet ISON - Cooked well done? new [Re: brianb11213]
      #6225219 - 11/30/13 01:36 PM

It's been a pretty good and memorable show the last couple days, just not the kind most of us were hoping for. Never got the chance to see myself but it was amazing to view the tracking as it made its run.

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Larry Patriarca
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Re: Comet ISON - Cooked well done? new [Re: brianb11213]
      #6225272 - 11/30/13 02:01 PM

Probably should have read more posts but I posted this in a couple other ISON threads too. I'll be interested if this conversation has been covered yet.

You'll have to pardon my jumping in here, I will admit I have not read much of any of the forum posts (anywhere) regarding comet Ison except a handful in this particular thread, so I apologize if I'm regurgitating older discussions. But I will say that my info is important since it allowed me to not only predict that Ison would survive fully intact, but also predict when the tail/coma would fade before perihelion, and when it would rekindle after perihelion (at + or - about 10 minutes), and predicted that they would claim it disintegrated just to eat their words later.

My consensus is the same as most, experts are getting it totally wrong for some reason, but because their perspective relies on explaining why water/ice is not performing as predicted, and as long as water remains the center of focus, the mystery will not be solved. The problem? Every water test on comets has proven to be either inadequate or impossible. The conclusion is simple, it can't be water/dust that is responsible, it must be something else and the biggest clue is the vanishing act of the tail/coma during closest approach. This is not something new, every surviving sun grazer shows the same event; as it approaches perihelion, its tail vanishes and then grows anew as it recedes from the sun. Only the “experts” talk like this is something new and unexplainable. This 3 minute NASA video about ISON shows an example in the first 10 seconds, and an even better example in the last 30 seconds of 2 other sun grazers losing their tails and comas on approach and growing them back when receding. http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey/

If water is responsible, the tail would be at its longest specifically when at its closest, not vanish entirely (and on every example to date) to just sprout a new tail from dust/water that wasn't there at perihelion. If there is not enough ice/water/dust present and all traces vanish at perihelion (from ALL the satellites that were watching the journey around the sun), then how can it re-emerge with enough ice/water/dust to produce an equally grand tail post and prior to perihelion, and, consistently brighten/expand as it recedes from the sun? If there’s only so much debris/water left over, it should either dim as it expands, or condense as it brightens, yet all comets do the opposite. How can Halley’s comet make repeated grand showings at similar magnitudes yet show no signs of diminishing brightness as it supposedly dumps megatons of water on each pass? How can comets even be sporting comas/tails at temperatures of –300 degrees F and distances in excess of 500 million miles from the sun? Temperature/pressure/speed in a near vacuum can’t accomplish this.

It cannot be explained by water, but it can be explained by electricity; a body in a steady circular orbit maintains a balanced electrical charge while a body in an eccentric orbit sports a coma or tail depending on how fast it is receding or approaching the sun. A comet during its perihelion, travels in a somewhat steady radius for a measurable time (evidenced in the 3 examples now given, from the time the tail vanishes until the time it starts to grow again when receding from the sun), barely changing its distance until slung shot out where it begins to change distance rapidly and produce glowing ionized particles again, similar to our own northern lights.

While sublimating water can’t be proven correctly, or at all, electrical experimentation can; this short youtube video shows a static electricity experiment lighting up a neon bulb.
http://www.youtube.com/watch?v=Ij0sYowaZl0 Towards the end, you’ll see where a 4’ neon tube is brought close to the electrical field, but it isn’t until the tube is pointed directly at the source that it glows, then a second tube is brought into the scene but never glows correctly, why? Because he continually holds the bulb at a tangent to the source, never perpendicular or pointed at it. In this example, the non-energized bulb is similar to an object moving in a steady circular orbit, not changing its relative distance from the sun or electric source, while the lit bulb represents an object diving towards or receding from the sun.

The pattern of Ison’s unexplained brightening spurts can be attributed to encounters with Jupiter, Mars, and Mercury. The distances at conjunctions with each planet (Mars being close at 7 million miles) are too vast and the bodies involved are too small to explain the brightening by temperature changes; but it can be explained with the passing of an electrified body thru a magnetic “wake” created by the orbit of the planet itself energizing the comet a little more than the sun was doing by itself causing a jump in brightness followed by a slight dimming on each occasion. You only need 3 examples to know something is absolute, and presented here is 3 examples of sun grazers and their vanishing/reoccurring tails/comas, and 3 examples of planetary encounters defying the dirty snowball theory as well.

I invite those interested to review the documentary “The Electric Comet”, http://www.youtube.com/watch?v=34wtt2EUToo , the electrical phenomena is discussed at length here. Anyone ever hear of the Halley’s comet outburst that occurred out past the orbit of Saturn halfway to Uranus?

Larry


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MessiToM
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Re: Comet ISON - Cooked well done? new [Re: Larry Patriarca]
      #6225420 - 11/30/13 03:33 PM

NASA SOHO. ISON is a faint smudge
http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.html

[image]http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.html[/image]

Edited by MessiToM (11/30/13 03:34 PM)


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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: MessiToM]
      #6225474 - 11/30/13 04:11 PM

Quote:

I really hate to agree with you ^ because I so badly wanted this to put on a show in the dawn sky



I would have liked to see the Great Comet of 2013 too. But all the hype in the world doesn't change reality.


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brianb11213
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Re: Comet ISON - Cooked well done? new [Re: Larry Patriarca]
      #6225566 - 11/30/13 05:09 PM

Quote:

How can Halley’s comet make repeated grand showings at similar magnitudes yet show no signs of diminishing brightness as it supposedly dumps megatons of water on each pass?



That one is easy to explain. The nucleus of Halley's Comet has a mass of 2.2 x 10^14 kg (as measured by deflection of spacecraft oribits during the 1986 pass) - that's 220,000 million tonnes. It can lose a few million tonnes of material every 76 years for many millenia before the mass loss is a significant proportion of the initial mass.

Incidentally Halley's perihelion is approximately 0.6 AU i.e the heating at perihelion is of the order of 0.03% of that suffered by Ison, which was very much smaller to start off with.


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djeber2
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Re: Comet ISON - Cooked well done? new [Re: ohioalfa64]
      #6225650 - 11/30/13 06:03 PM

Quote:

Did anyone receive permission to use Miley and Kim references on this site? Someone better call Bruce Jenner and ask.




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GlennLeDrew
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Re: Comet ISON - Cooked well done? new [Re: djeber2]
      #6225709 - 11/30/13 06:47 PM

Larry,
The 'vanishing tail' near perihelion is certainly explainable with simple dynamics. The great acceleration (in both speed and direction) causes the tail particles to sweep out a very much greater area/volume, and hence the huge decrease in density. And the great difference in velocity vectors of the nucleus and solar wind--about 45 degrees--must do much to suppress any tendency for a radially oriented tail. Lastly, there *could* be an 'outrunning' or ram pressure stripping process to cause the nucleus to *seemingly* stop producing any significant coma. Then once the acceleration decreases and tye velocity vectors of the nucleus and solar wind more closely align, the usual aspect re-establishes.


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Alan French
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Re: Comet ISON - Cooked well done? new [Re: GlennLeDrew]
      #6225820 - 11/30/13 07:50 PM Attachment (29 downloads)

We've canceled. I'd be quite happy to proven wrong, but I think optimistic views of Comet ISON's future are just wishful thinking. Check out the latest at Spaceweather.

Clear skies, Alan

Edited by Alan French (11/30/13 07:53 PM)


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jwaldo
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Re: Comet ISON - Cooked well done? new [Re: Alan French]
      #6225840 - 11/30/13 08:04 PM

Rats. I guess I'll have a peek at Lovejoy tomorrow morning and keep my fingers crossed that there'll actually be another Great Comet in my lifetime...

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rdandrea
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Re: Comet ISON - Cooked well done? new [Re: jwaldo]
      #6225951 - 11/30/13 09:12 PM

Quote:

...and keep my fingers crossed that there'll actually be another Great Comet in my lifetime...




Depending on how old you are, there will be.


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star dropModerator
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Re: Comet ISON - Cooked well done? new [Re: Alan French]
      #6225984 - 11/30/13 09:43 PM

Quote:

We've canceled. I'd be quite happy to proven wrong, but I think optimistic views of Comet ISON's future are just wishful thinking. Check out the latest at Spaceweather.

Clear skies, Alan



I saw that.


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jwaldo
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Re: Comet ISON - Cooked well done? new [Re: rdandrea]
      #6226029 - 11/30/13 10:10 PM

Quote:

Quote:

...and keep my fingers crossed that there'll actually be another Great Comet in my lifetime...




Depending on how old you are, there will be.




Oh, I'm sure there will be, but whether I see it is another thing. I'm 0 for 3 unless you count one iffy daytime McNaught observation. Luck hasn't been on my side so far


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SteveRosenow
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Re: Comet ISON - Cooked well done? [Re: jwaldo]
      #6226318 - 12/01/13 02:11 AM

And with that, ISON is now out of the view of the LASCO C3.

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Tonk
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Re: Comet ISON - Cooked well done? new [Re: SteveRosenow]
      #6226481 - 12/01/13 07:42 AM

Quote:

But I will say that my info is important since it allowed me to not only predict that Ison would survive fully intact, but also predict when the tail/coma would fade before perihelion, and when it would rekindle after perihelion (at + or - about 10 minutes), and predicted that they would claim it disintegrated just to eat their words later.




Cool - I was thinking that it would be possible to simulate much of what we are seeing with software such as this

http://loke.as.arizona.edu/~ckulesa/astrosoft.html

At least if you hypothesis that the comet acted either as a single solid body or a swarm of loosely associated particals or a graduation between these extremes then you can test which produces a result closest to what was observed.

The fly in the oitment with this idea and using the linked software is you need to handle significant non gravitational interactions (photon pressure, solar wind velocity and density, comet partical mass sizes and distributions, solar energy input, composition and latent heat of vaporization of those materials) which suggests that some modifications would be needed unless someone can point me to existing software for modelling comet breakups (or similar).

Starting of with a swarm of particals interacting with just gravitational forces should model most of the aspects of how the dust tail sweeps out post perihelion from our POV. It would be a good starting point after which the other forces can be introduced


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Rich (RLTYS)Moderator
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Re: Comet ISON - Cooked well done? new [Re: Alan French]
      #6226506 - 12/01/13 08:17 AM

Quote:

We've canceled. I'd be quite happy to proven wrong, but I think optimistic views of Comet ISON's future are just wishful thinking. Check out the latest at Spaceweather.

Clear skies, Alan




That's a bummer. I never did get a chance to visually see it.

Rich (RLTYS)


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Tonk
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Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6226511 - 12/01/13 08:22 AM

OK - the answer is the Max Plank Institute (for one) has such software and they are already running simulations on ISON's perihelion passage.

http://www.mpg.de/7621979/winged-comet

From that link ...

Quote:

"The dust tail of the comet is now divided into two parts," explains Hermann Böhnhardt from the Max Planck Institute for Solar System Research. According to Böhnhardt, the part of the tail that is pointing towards the sun consists of dust particles, which were released significantly before the comet's Perihelion passage – i.e. prior to reaching the closest point to the sun.

The other part, however, appears to contain more recent material: It was released when ISON passed the sun and suggests that at least part of the nucleus still existed and was active at that time.

The Max Planck researchers base their assessment on computer simulations in which they model the shape of the dust tail. "If we assume in our calculations that the comet has emitted dust at Perihelion, we can reproduce the current images quite well," says Böhnhardt.




Good to see someone is hard at it finding out via detailed simulations what is happening

And who is eating their words now?


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