Starship Asterisk*

Astro Bob wrote:ISON-Juan-Carlos-Casado.jpg
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.

ta152h0 wrote:
The Pacific Northwest region suddenly is totally clear of clouds, completely clear.
and for the next week or so [sic].

http://en.wikipedia.org/wiki/Cannabis_%28drug%29#Legal_status wrote:
<<Cannabis, also known as marijuana, is a preparation of the Cannabis plant intended for use as a psychoactive drug. On December 6, 2012, the U.S. state of Washington became the first state to officially legalize cannabis in a state law (Washington Initiative 502)>>

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]

---

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.>>

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

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

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.

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.>>

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.

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.>>

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.

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.

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

Ann

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.

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

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

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

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