APOD: Active Comet ISON (2013 Nov 16)

APOD Robot · Post by **APOD Robot** » Sat Nov 16, 2013 5:07 am

Active Comet ISON

Explanation: Falling through planet Earth's predawn skies toward its close encounter with the Sun on November 28, Comet ISON is coming to life. The much anticipated comet has now been reported to have substantially increased in brightness, surging to naked-eye visibility for dark sites and sprouting a more complex tail. ISON's tail stretches over two degrees in this telephoto skyview from southern Kenya, captured on the morning of November 14. Shown in two panels, the enlarged negative version on the right makes details of the long tail easier to trace, including the tail's separated filaments toward the top of the frame. A sungrazer and first time visitor to the inner solar system, the possibility of ISON's survival to become a bright comet in planet Earth's December skies remains a question.

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Boomer12k · Post by **Boomer12k** » Sat Nov 16, 2013 10:02 am

Ooooooooo....I hope to be able to see it on the way out!!!!!

:---[===] *

jimbo48 · Post by **jimbo48** » Sat Nov 16, 2013 3:22 pm

There are several faint galaxies in the background.
Anybody know the designation of the bright galaxy below the comet in the frame?

stephen63 · Post by **stephen63** » Sat Nov 16, 2013 3:48 pm

jimbo48 wrote:There are several faint galaxies in the background.
Anybody know the designation of the bright galaxy below the comet in the frame?

NGC4697

Joe Stieber · Post by **Joe Stieber** » Sat Nov 16, 2013 3:55 pm

jimbo48 wrote:Anybody know the designation of the bright galaxy below the comet in the frame?

The bright star at the bottom-right corner of the panel on the left is magnitude 6.3 HR 4856. The prominent galaxy below-left of that is magnitude 10.1 NGC 4697. Based on the positions of these objects relative to the comet, the picture was actually taken on the morning of November 14, not November 15 as stated in the text description.

As of 11:30 am EST, the date has been corrected in the text of the home page, but not at the top of the Asterisk page.

neufer · Post by **neufer** » Sat Nov 16, 2013 4:18 pm

stephen63 wrote:
jimbo48 wrote:
There are several faint galaxies in the background.

Anybody know the designation of the bright galaxy below the comet in the frame?
NGC4697

That would explain why Comet ISON looks like an X-ray:

. http://apod.nasa.gov/apod/ap020617.html
. http://chandra.harvard.edu/press/02_rel ... 60402.html

Anthony Barreiro · Post by **Anthony Barreiro** » Sat Nov 16, 2013 6:36 pm

I saw Comet ISON (C/2012 S1) through 11x56 binoculars at 0535 PST yesterday morning, 15 November, from Jose Coronado Playground in San Francisco. Clear weather. The comet was small, bright (6th magnitude?), and obviously non-stellar, 7.5 degrees WSW of Spica, between theta and psi virginis. I didn't see any tail, just the small coma. I'm rather pleased with myself. ISON is not yet the comet of the century, but worth a look.

alter-ego · Post by **alter-ego** » Sat Nov 16, 2013 6:51 pm

Joe Stieber wrote: The bright star at the bottom-right corner of the panel on the left is magnitude 6.3 HR 4856. The prominent galaxy below-left of that is magnitude 10.1 NGC 4697. Based on the positions of these objects relative to the comet, the picture was actually taken on the morning of November 14, not November 15 as stated in the text description.

As of 11:30 am EST, the date has been corrected in the text of the home page, but not at the top of the Asterisk page.

Babak states Nov 14 as the date in the this telephoto skyview link

Ann · Post by **Ann** » Sat Nov 16, 2013 7:06 pm

It looks as if there were shells of some sort around elliptical galaxy NGC 4697. Or is that comet tail material?

Ann

alter-ego · Post by **alter-ego** » Sat Nov 16, 2013 8:03 pm

Ann wrote:It looks as if there were shells of some sort around elliptical galaxy NGC 4697. Or is that comet tail material?

Ann

I'm not sure what your looking at. Are you referring to the left pane? I do see what appears to be shell-like structure around the lower right star in the right pane.

ta152h0 · Post by **ta152h0** » Sat Nov 16, 2013 8:40 pm

I there a difference between an interstellar comet and an Oort cloud comet ? It seems like this beast is coming in very fast and quite possibly never to return.

Chris Peterson · Post by **Chris Peterson** » Sat Nov 16, 2013 8:50 pm

ta152h0 wrote:I there a difference between an interstellar comet and an Oort cloud comet ? It seems like this beast is coming in very fast and quite possibly never to return.

An interstellar comet would be one that came from the Oort cloud (or some other structure) of a different star. None have been observed.

This comet has an eccentricity of 1.000002, which isn't enough to establish it as being in a truly hyperbolic orbit. This eccentricity is typical of comets perturbed from the Oort cloud. It is statistically likely to end up in a long period closed orbit around the Sun, but it won't be possible to determine that before it is well beyond Jupiter's orbit again (assuming it remains observable).

Ann · Post by **Ann** » Sat Nov 16, 2013 8:58 pm

alter-ego wrote:
Ann wrote:It looks as if there were shells of some sort around elliptical galaxy NGC 4697. Or is that comet tail material?

Ann
I'm not sure what your looking at. Are you referring to the left pane? I do see what appears to be shell-like structure around the lower right star in the right pane.

Yes, I'm referring to the right pane. The comet is not in the same position in relation to the galaxy in the left and the right pane.

Ann

neufer · Post by **neufer** » Sat Nov 16, 2013 9:04 pm

ta152h0 wrote:
I there a difference between an interstellar comet and an Oort cloud comet ?
It seems like this beast is coming in very fast and quite possibly never to return.

An interstellar comet should have an eccentricity significantly greater than one.

Comet ISON's eccentricity near perihelion of 1.0000021
(boosted by closely approaching the orbiting sun from behind?) doesn't qualify.

http://en.wikipedia.org/wiki/C/2012_S1 wrote:
Comet ISON:

Perihelion 0.01244 AU (q)
Eccentricity 1.0000021
Orbital period ejection trajectory (epoch 2050)
Inclination 62.39°

http://en.wikipedia.org/wiki/Comet#Long_period wrote:
<<Long-period comets have highly eccentric orbits and periods ranging from 200 years to thousands or even millions of years. An eccentricity greater than 1 when near perihelion does not necessarily mean that a comet will leave the Solar System. For example, Comet McNaught had a heliocentric osculating eccentricity of 1.000019 near its perihelion passage epoch in January 2007 but is bound to the Sun with roughly a 92,600-year orbit because the eccentricity drops below 1 as it moves further from the Sun. The future orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System.

Single-apparition or non-periodic comets are similar to long-period comets because they also have parabolic or slightly hyperbolic trajectories when near perihelion in the inner Solar System. However, gravitational perturbations from giant planets cause their orbits to change. Single-apparition or comets are those with a hyperbolic or parabolic osculating, which makes them permanently exit the Solar System after a single pass of the Sun. The Sun's Hill sphere has an unstable maximum boundary of 230,000 AU (1.1 parsecs). Only a few hundred comets have been seen to achieve a hyperbolic orbit (e > 1) when near perihelion that using a heliocentric unperturbed two-body best-fit suggests they may escape the Solar System. No comets with an eccentricity significantly greater than one have been observed, so there are no confirmed observations of comets that are likely to have originated outside the Solar System. Comet C/1980 E1 had an orbital period of roughly 7.1 million years before the 1982 perihelion passage, but a 1980 encounter with Jupiter accelerated the comet giving it the largest eccentricity (1.057) of any known hyperbolic comet. Comets not expected to return to the inner Solar System include C/1980 E1, C/2000 U5, C/2001 Q4 (NEAT), C/2009 R1, C/1956 R1, and C/2007 F1 (LONEOS).

Early observations have revealed a few genuinely hyperbolic (i.e. non-periodic) trajectories, but no more than could be accounted for by perturbations from Jupiter. If comets pervaded interstellar space, they would be moving with velocities of the same order as the relative velocities of stars near the Sun (a few tens of kms per second). If such objects entered the Solar System, they would have positive specific orbital energy and would be observed to have genuinely hyperbolic trajectories. A rough calculation shows that there might be four hyperbolic comets per century within Jupiter's orbit, give or take one and perhaps two orders of magnitude.>>

neufer · Post by **neufer** » Sat Nov 16, 2013 9:34 pm

http://www.space.com/14704-sun-stolen-comets-oort-cloud.html wrote:
[url=http://www.toonpool.com/cartoons/am%20I%20adopted%3F_8342][size=150]By toons on March 18, 2008[/size][/url]
Many Solar System Comets May Be Sun's Stolen Goods
by Clara Moskowitz, SPACE.com, February 28, 2012

<<Astronomer Stephen Levine of Lowell Observatory in Flagstaff, Ariz., and undergraduate student Catherine Gosmeyer of Indiana University created a computer simulation to calculate how often stars would be likely to exchange comets when they passed close by each other, as stars often do in the course of their lives orbiting the center of the galaxy. "It turns out it's much more frequent than in fact even I would have guessed," Levine told SPACE.com.

By looking at the number and spread of stars in the sun's neighborhood, the researchers found that other stars would pass reasonably close by the sun every 1 to 2 million years. That means that the sun has probably had between 10,000 to 50,000 close encounters over its lifetime. And any one of these could easily have caused the sun to gain or lose comets, the simulations suggest. The researchers calculated that at least 5 percent of the Oort cloud comets are likely to be adopted from other stars, though the true figure could be much higher.

And the encounters were probably two-way transactions; just as the sun may have gained new comets, it just as likely lost some of its own. "I might not be able to say we have increased the size of the Oort cloud, but we have probably exchanged material at least, so that some fraction of what's in our cloud probably did come from something else," Levine said.

Testing this hypothesis could be difficult, though, the scientists cautioned. For one thing, we cannot be sure other stars even have Oort clouds of their own, as tiny comets would be too dim to detect around any star but the sun. However, Levine said there's no reason to believe our sun is unique in this trait. Furthermore, it could prove tough to identify any particular comets around the sun that may have originated elsewhere. One possibility is to study the chemical composition of the sun's comets to see if they match that of the sun. If not, they may have formed around other stars with different chemical abundances.

The researchers said the general idea that some of the Oort cloud members may be interlopers does make sense. For one thing, the sun seems to have more comets in its Oort cloud than were predicted based on calculations of how much mass was thought to originate in the sun's close environs when it was forming. Gosmeyer presented the findings in a poster at the 219th meeting of the American Astronomical Society in Austin, Texas in January.>>

alter-ego · Post by **alter-ego** » Sat Nov 16, 2013 10:56 pm

Ann wrote:
alter-ego wrote:
Ann wrote:It looks as if there were shells of some sort around elliptical galaxy NGC 4697. Or is that comet tail material?

Ann
I'm not sure what your looking at. Are you referring to the left pane? I do see what appears to be shell-like structure around the lower right star in the right pane.
Yes, I'm referring to the right pane. The comet is not in the same position in relation to the galaxy in the left and the right pane.

That's what I thought. The confusion is the right pane is a zoomed in view of the left pane. The galaxy is not visible in the right (negative) pane. You'll note the comet's position wrt the star field is the same in both panes. The star in the lower right pane your referring to is HIP 62190. Since the comet is heading SE towards the star, there is no comet tail material there (yet). The Sloan Survey shows no nebulous shell structure around 62190.

Orienting oneself is a bit confusing here. The image orientation is South to the right, and East down.

Edit: After closer zoomed-in inspection of star images, the answer is revealed. There is an asymmetry in the stellar intensity distribution. For the brighter stars in the left pane, the star images are brighter to one side while in the right (negative) pane, an offset partial ring is visible. These are all artifacts.

Ann · Post by **Ann** » Sun Nov 17, 2013 5:53 am

alter-ego wrote:
The star in the lower right pane your referring to is HIP 62190.

I thought the star I was referring to was HD 111199, HIP 62421, a sixth magnitude star. I can see now that the star field around NGC 4697 and HIP 62190 doesn't match the star field around the galaxy that I took to be NGC 4697 and the star that I took to be HIP 62421 in the right-hand panel. But neither does it match if the star is HIP 62190.

Instead, I'd say that the star is HIP 62419, a ninth magnitude star. And the galaxy that I can see to the left of it - right inside the upper part of the comet's tail - does seem to have some kind of "fluff" around it, but that could obviously be comet tail material.

Edit: Groan. Now I don't know if the star is is HIP 62419, either. All I know is that there is definitely a galaxy with some sort of fluff (galactic or cometary) around it in the upper part of the comet's tail in the right pane. Above the galaxy with fluff, there is a star(?) that seems to have sprouted a tail of its own. The tail looks almost like an inverted "S". This, too, may of course be a part of comet ISON's tail.

Ann

alter-ego · Post by **alter-ego** » Sun Nov 17, 2013 7:14 am

Ann wrote:
alter-ego wrote:
The star in the lower right pane your referring to is HIP 62190.
I thought the star I was referring to was HD 111199, HIP 62421, a sixth magnitude star. I can see now that the star field around NGC 4697 and HIP 62190 doesn't match the star field around the galaxy that I took to be NGC 4697 and the star that I took to be HIP 6241 in the right-hand panel. But neither does it match if the star is HIP 62190.

Instead, I'd say that the star is HIP 62419, a ninth magnitude star. And the galaxy that I can see to the left of it - right inside the comet's tail - does seem to have some kind of "fluff" around it, but that could obviously be comet tail material.

Ann

Well, Ann, I'm still confused. HIP 62419 is located near (16 arcminutes) NGC 4697, and is about 1° "ahead" of the comet i.e. the tail is flowing the opposite direction. HIP 62419 is also not visible in the right pane.
Now the most obvious galaxy that is immersed in the tail is NGC 4593, a barred-spiral Seyfert galaxy, and is also visible in the right (negative) pane. It happens to also be ≈15 arcminutes to the left of a 9th magnitude star. There is clearly fluff around 4593 - some of it is the comet tail, and some due to the spiral structure. It looks to me that this is the galaxy you're talking about. Now looking at that 9th magnitude star, I do see some fuzz, but it isn't clear to me it's related to the comet tail.

Ann · Post by **Ann** » Sun Nov 17, 2013 9:14 am

Thanks, alter-ego! NGC 4593 is the galaxy I've been talking about.

Ann

Hukadarn · Post by **Hukadarn** » Sun Nov 17, 2013 1:48 pm

Important update about ISON:

"Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network

COMET C/2012 S1 (ISON)
H. Boehnhardt, C. Tubiana, N. Oklay, and J. B. Vincent, Max Planck
Institute for Solar System Research, Katlenburg-Lindau; and U. Hopp, C. Ries,M. Schmidt, A. Riffeser, and C. Goessl, Astronomical Institute, Ludwig Maximilian University, Munich, report the detection of coma wings in Laplace-filter-processed CCD exposures of comet C/2012 S1 obtained with the 0.4-m telescope of the Mt. Wendelstein Observatory on Nov. 14.16-14.21 and 16.16-16.21 UT. The arclet-like wings appeared in opposite direction from the nucleus at position angles 15 and 195 deg on Nov. 14 and at p.a. 25 and 205 deg on Nov. 16. The coma wings extended straight from the nucleus for about 4700 km on Nov. 14 and 13500 km on Nov. 16 on either side of the extended radius vector and continued in streamers of the plasma tail. No coma wings were found in similar exposures obtained on Nov. 13. The coma wings suggest the presence of two or more sub-nuclei with individual expanding atmospheres in the overall cometary coma and may indicate recent
nucleus splitting in the comet."

In really the nucleus of ISON now shows the same jets estructures like the comet 2001 A2 (LINEAR) and comet C/1999 S4 (LINEAR):

-

-

This jets already cause some evident "wing tails" inside ISON Coma:

Regards !

owlice · Post by **owlice** » Sun Nov 17, 2013 2:10 pm

Cooooooool!!! Thanks!

Hukadarn · Post by **Hukadarn** » Sun Nov 17, 2013 6:29 pm

Confirmation of the breakup of the nucleus of the comet ISON in two fragments

Image captured by Jean-Francois Soulier yesterday morning, Nov. 16, between 0500 and 0600 UT and processed by Toni Scarmato.

Break up of the nucleus of Comet ISON detected in the image of Bruce Gary of November 14, 2013, processed by Toni Scarmato.

source: http://digilander.libero.it/infosis/hom ... omet1.html

Regards !

neufer · Post by **neufer** » Sun Nov 17, 2013 6:47 pm

Click to play embedded YouTube video.

: [b][color=#0000FF]Processed images showing a possible jet extending southeast (PA 150 degrees) of Comet ISON’s nucleus as well as the new wing-like hoods on Nov. 17, 2013. Credit: Denis Buczynski and Nick James of the BAA[/color][/b]

http://www.universetoday.com/106477/comet-ison-grows-wings-comet-lovejoy-a-fountain/#more-106477 wrote:
[b][color=#0000FF]Nightly images of Comet Hale-Bopp’s rotating nucleus and spiraling jet made March 24-30, 1997 : Brad D. Wallis of JPL[/color][/b]
Comet ISON Grows Wings
by Bob King,
Nov. 18, 2013

<<Sometimes material sprayed by jets expands into a curved parabolic hood within the coma. This may explain the wing-shaped structures poking out from Comet ISON’s coma seen in recent photos. Possibly the Nov. 14 outburst released a great deal of fresh dust that’s now being pushed back toward the tail by the ever-increasing pressure of sunlight as the comet approaches perihelion.

The inner coma of Comet Hale-Bopp developed a striking series of hoods in March 1997 when a dust jet spewed material night after night from the comet’s rotating nucleus. The animation captures garden sprinkler effect beautifully. Since the nucleus spun around every 11 hours 46 minutes, multiple spiraling waves passed through the coma in the sunward direction. To the delight of amateur astronomers at the time, they were plainly visible through the telescope.>>

Beyond · Post by **Beyond** » Sun Nov 17, 2013 7:23 pm

Breaking up is hard to do, sometimes. That's why even Josephine's green comet sometimes needs a little elbow-grease assistance for separation.

neufer · Post by **neufer** » Fri Nov 22, 2013 9:38 pm

http://astrobob.areavoices.com/2013/11/22/finally-clear-skies-for-comet-ison-heres-what-i-saw/ wrote:
Clear skies for Comet ISON
Astrobob November 22, 2013

[b][color=#0000FF][size=125]The finest Comet ISON scenic shot I’ve seen to date. It was taken by Juan Carlos Casado from up on a mountaintop on the island of Gran Canaria from the Observatorio del Teide (IAC) Nov. 21, 2013. Mercury is seen through clouds at lower left.[/size][/color][/b]

Starship Asterisk*

APOD: Active Comet ISON (2013 Nov 16)

APOD: Active Comet ISON (2013 Nov 16)

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5% of Oort cloud comets may be adopted

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Comet ISON Grows Wings

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