[X] My Assistant

[Mongo]

The C3 image for 00:07 shows that the object is definitely getting brighter. Compared to the image from two hour earlier, I would guess that it's at least twice as bright (as far as I can tell from the small images).

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[Mongo]

STEREO-B COR2 at 00:25:

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[ElkGroveDan]

ISON - It's Alive!!!!!

It's REALLY ALIVE

[stevesliva]

Really? And I was just coming here to crack that it's only fitting the Sun got a meal today, too.

[Mongo]

Some recent Tweets from Karl Battams:

Sungrazer Comets @SungrazerComets 16m

Matthew Knight and I have looked at literally a couple of thousand sungrazing comets. We've NEVER seen one behave like #ISON. Astounding!

Sungrazer Comets @SungrazerComets 13m

"The more images we see, the less certain we are" <-- what I heard eavesdropping on Matthew on the phone. I concur.

[TheAnt]

Alive indeed, and claims of ISON's demise -as still can be read seen on so many sites like on the CometISON site in the UK: Update: Despite there being great hope for Comet ISON, it appears it disappeared behind the Sun today never to emerge again.

Yet the comet is very much "alive" indeed, and speedy as well, are these numbers correct? About 1,357,000 km/hr, or 843,000 miles/hr at perhelion? Anyhow now as when this is posted only a part of the tail can be seen in the C2 view.

Edit: Found a graph for you who use MPH.

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[Mongo]

Yet the comet is very much "alive" indeed, and speedy as well, are these numbers correct? About 1,357,000 km/hr, or 843,000 miles/hr at perhelion?

Yes. Or to put it another way, it was traveling at about 0.125% of the speed of light, relative to the Sun, at perihelion. It was REALLY motoring! Even now, it's still moving at about 0.07% of light speed, relative to the Sun.

[nprev]

Sungrazer Comets @SungrazerComets 16m

Matthew Knight and I have looked at literally a couple of thousand sungrazing comets. We've NEVER seen one behave like #ISON. Astounding!

SCIENCE!!!!!

[ElkGroveDan]

Yes. Or to put it another way, it was traveling at about 0.125% of the speed of light,

Quick, someone smarter than me please do the math and see how elongated it became from traveling that fast.

[nprev]

Nothing perceptible; the Lorenz-Fitzgerald transformations are exponential, so you can't see much visually at anything less than around 85% of light speed IIRC (been a LONG time since my last physics class...) Also, it would have appeared to compress along the line of travel to an outside observer.

[ElkGroveDan]

I tried to do the math but getting that that close to the sun caused my frame of reference to melt.

[Mongo]

Sungrazer Comets @SungrazerComets 27s

Alright we're calling it, and you heard it here first: We believe some small part of #ISON's nucleus has SURVIVED perihelion.

[Mongo]

posted by chergen at comets-ml

RE: Answers please

Denis,

I'd say there are a number of things that might be going on here.

1) The nucleus of ISON has disrupted into many smaller pieces. It is this cloud of mini-nuclei that continues to sublimate. Rather than a condensed coma we now have a diffuse extended coma that should continues to spread out and fade as individual mini-nuclei move apart (due to variable solar radiation pressure and velocities from the disruption event) and disrupt further. This is what we've seem with other disintegrated comets such as C/1999 S4 (LINEAR) and C/2010 X1 (Elenin). Disruption does not mean the comet disappears instantaneously as the mini-nuclei can last for some days or weeks after disruption. In a way, the comet seems to just fall apart. Based on the SOHO images I've seen this is my guess for what is going on with ISON.

2) Much of ISON's coma consisted on small dust particles that were vaporized by the intense heat of the Sun. We saw something similar with C/2011 W3 (Lovejoy) as pointed out by Joe Marcus, Zdenek Sekanina and Paul Chodas in their papers on the subject. If this is the case with ISON, it should 'regrow' a strong coma and tail as it moves away from the Sun.

3) Phase angles effects are at play. While this could explain the decrease in brightness, it does not explain the smeared appearance of the coma.

4) We are seeing something we've never seen before.

John Bortle has mentioned the case of Seki-Lines in 1962. Like ISON, a dynamically new comet that approached to within a few hundredths of an AU of the Sun. Though it was bright prior to and after perihelion, it was not observable at the time of perihelion though it should have been an easy object. It was almost as if the comet turned off near perihelion. Perhaps it was the vaporization of its dust coma by the intense solar heat or something else, but it gives a second example of a comet (with Lovejoy) that seemed to fade out near perihelion only to come back strong afterwards.

Time will tell though the continued diffuseness and smeared look of ISON's coma makes me think a significant disruption has occurred. If we're lucky, enough of the nucleus remains in one piece to reform a more substantial coma and tail.

- Carl Hergenrother

[monty python]

I hope ISON doesn't follow the life cycle of the man in Monty Python And The Holy Grail's "bring out your dead" scene - check youtube!

[dilo]

Updated "combo" view:

(note the tail remnant in the lower/right region)