More Moons Around Pluto? |
More Moons Around Pluto? |
Dec 1 2005, 03:36 PM
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#76
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0511837
Date: Wed, 30 Nov 2005 19:37:52 GMT (124kb) Title: New Constraints on Additional Satellites of the Pluto System Authors: A.J. Steffl, M.J. Mutchler, H.A. Weaver, S.A.Stern, D.D. Durda, D. Terrell, W.J. Merline, L.A. Young, E.F. Young, M.W. Buie, and J.R. Spencer Comments: 18 pages including 4 figures \\ Observations of Pluto and its solar-tidal stability zone were made using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) on UT 2005 May 15 and UT 2005 May 18. Two small satellites of Pluto, provisionally designated S/2005 P 1 and S/2005 P 2, were discovered and are reported by (Weaver et al. 2005). These observations also provide strong constraints on the existence of any additional satellites of Pluto. We place a 90%-confidence lower limit of V=26.2 (V=27.1 for a 50%-confidence lower limit) on the magnitude of undiscovered satellites >5" from Pluto. Assuming an albedo of p_v=0.04 (similar to cometary nucleii and a reasonable lower limit), this corresponds to a limiting diameter of 37 km at 90%-confidence (25 km at 50-confidence). For an assumed albedo similar to Charon, i.e p_v=0.38, the magnitude limit corresponds to a limiting diameter of 12 km at 90%-confidence (8 km at 50%-confidence). At distances <5" from Pluto, scattered light from both Pluto and Charon degrades the sensitivity of our search, such that at 1.7" from Pluto the 50%-confidence magnitude limit is V=25.3, corresponding to a limiting diameter of 57 km for an object with p_v=0.04. \\ ( http://arXiv.org/abs/astro-ph/0511837 , 124kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Dec 7 2005, 02:42 AM
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#77
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Member Group: Members Posts: 509 Joined: 2-July 05 From: Calgary, Alberta Member No.: 426 |
It's good to see that some abstracts are starting to come out of the two new Plutonian moons.
Not to harp on this too much, but I'm still *really* interested to see how much Charon perturbs their orbits. A few weeks back (in this thread) I tried to figure out a rough estimate of this effect, but my attempt was ridiculously oversimplified as it didn't take into account the rotating frame of reference (as seen from 2005 P1 and P2). It'll be neat to see the real solution. |
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Dec 17 2005, 09:50 PM
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#78
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Junior Member Group: Members Posts: 87 Joined: 19-June 05 Member No.: 415 |
QUOTE (Rob Pinnegar @ Dec 6 2005, 08:42 PM) Not to harp on this too much, but I'm still *really* interested to see how much Charon perturbs their orbits. The article in the link and the original one both indicate that the new moons are in resonant orbits with Pluto-Charon and their 6.3 day rotation. They may be in the fourth and sixth harmonic orbits. (I don't have the original article to repeat the calculation.) Whether you can say that Charon "perturbs" the orbit or "regulates" them is semantics, but the system isn't chaotic. As for your simple model, determining how large the libration swings can be would require some real sophistication. |
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