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Posted by: LivingNDixie Sep 25 2007, 02:29 PM

There is an occulation on Sept 27 that someone thinks might prove that Pluto has rings.

http://occult.mit.edu/research/occultations/Pluto/P507-preds/

Posted by: ugordan Sep 25 2007, 02:31 PM

Wasn't there another recent Pluto occultation that suggested there weren't any rings or am I imagining things?

Posted by: Phil Stooke Sep 25 2007, 02:33 PM

Well, the occultation can be used to search for rings.

Phil

Posted by: ugordan Sep 25 2007, 02:35 PM

That I know. That's why I thought an (imaginary?) recent one failed to detect any signs of rings in the lightcurves.

Posted by: Alan Stern Sep 25 2007, 02:36 PM

Yes, but the tighter constraints are from HST. See The Astronomical Journal last summer, Steffl's article.

Posted by: tasp Sep 25 2007, 03:46 PM

Well, considering the effect of a very thin, but nevertheless quite deep atmosphere (up to the Roche limit ?) on any putative ring system and it would scarcely be worth the effort to look, in my view.

Think about it, a ring system orbiting inside an atmosphere, how long would that persist ??

Posted by: Phil Stooke Sep 25 2007, 06:01 PM

Quite right (of course) Alan - I was really intending to respond to the comment by LivingNDixie: " There is an occultation on Sept 27 that someone thinks might prove that Pluto has rings. " - the occultation observations aren't 'to prove Pluto has rings' but to see if any can be detected.

tasp - they wouldn't be inside the atmosphere. It would be more like dust eroded by impacts off the small inner moons. People have suggested the same for Mars.


Phil

Posted by: dvandorn Sep 25 2007, 10:27 PM

Pluto and Charon form a double-planet system, with the epicenter nearly outside of Pluto's surface. Is such a system gravitationally capable of maintaining a ring system for more than a few decades?

-the other Doug

Posted by: tasp Sep 26 2007, 01:37 AM

* If we are defining rings as material above the Roche limit . . .


* Regarding perturbations of a Plutonian ring system by Charon (and vice versa), that would indeed disrupt the 'collapse to the Laplacian' plane phase of ring formation from an impact lofted debris cloud. Materials would be far more likely to contact the surface prior to establishment of the 'classic' equatorially flattened form.

If the rings did manage to form, the dynamical ring spreading (DRS) process (explained in The New Solar System, Planetary Rings chapter) would emplace the ring to the surface very quickly. DRS is minimal (but still operating) with all the ring particles in perfectly circular orbits. The presence of Charon would elipticize (is that a word ??) the ring particles orbits significantly, and GREATLY accelerate the transfer of angular momentum throughout the ring plane and collapse the ring system.

As much as I like ring systems (check out Iapetus threads), sadly, Pluto doesn't have a chance.

Posted by: remcook Sep 26 2007, 08:47 AM

Isn't this similar?
http://www.space.com/imageoftheday/image_of_day_060113.html (sorry couldn't quickly find another link)

Posted by: SigurRosFan Sep 26 2007, 10:40 AM

Yes, maybe ...

- http://hubblesite.org/newscenter/archive/releases/2006/09/ (February 22, 2006)

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Astronomers believe that the formation of the Pluto system is similar to that of our Earth and Moon. In both cases a comparable-sized body slammed into the parent planet. Simulations show that debris from the collision would go into an orbit around the planet and coalesce to form one or more satellites.
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Posted by: PhilCo126 Sep 29 2007, 06:26 PM

We'll probably have to wait until the " New Horizons " fly by of the Pluto-Charon system to know if there're rings.
From the spacecraft's position, the occultation won't be obvious I guess?

Posted by: tasp Sep 30 2007, 03:08 AM

Quote,
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Astronomers believe that the formation of the Pluto system is similar to that of our Earth and Moon. In both cases a comparable-sized body slammed into the parent planet. Simulations show that debris from the collision would go into an orbit around the planet and coalesce to form one or more satellites.
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And we have another body, currently under study by Cassini, Iapetus, with an amazing collisional history of it's own.

We see the 'wedge ramp', quite plausibly (AFAIAC, confirmed, btw) the emplaced remnant of a ring system. We also have a mighty odd elongated crater on the SE edge of Cassini Regio.

The source crater of the ring system ?? (think about it, rings, ring residue, and source crater all there to study)


Seems like the New Horizon team might want to spend some time on this, the compelling relevance of this feature on Iapetus to the apparent collisional heritage of Charon/Pluto is astonishing. The synergy of further Iapetan investigation to the New Horizon mission investigations into the origins of the Pluto/Charon/Nix/Hydra system is a win-win for both mission science teams.

Considering applicability of this research into understanding the origins of earth's moon, and the possibility of manned Orion /Ares mssions to our moon in the next decade to further these studies, we are on the verge of a fundamental quantum increase in our understanding of this collisional phenomena.


Cassini has to go back to Iapetus.