More Moons Around Pluto? |
More Moons Around Pluto? |
Oct 31 2005, 05:49 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Press Release Source: NASA
NASA's Hubble Reveals Possible New Moons Around Pluto Monday October 31, 12:30 pm ET WASHINGTON, Oct. 31 /PRNewswire/ -- Using NASA's Hubble Space Telescope to view the ninth planet in our solar system, astronomers discovered Pluto may have not one, but three moons. If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system; Kuiper Belt Objects with satellite systems; and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune's orbit. "If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery. Pluto was discovered in 1930. Charon, Pluto's only confirmed moon, was discovered by ground-based observers in 1978. The planet resides about 3 billion miles from the sun in the heart of the Kuiper Belt. "Our result suggests other bodies in the Kuiper Belt may have more than one moon. It also means planetary scientists will have to take these new moons into account when modeling the formation of the Pluto system," said Alan Stern of the Southwest Research Institute, Boulder, Colo. Stern was co-leader of the research team. The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed approximately 27,000 miles away from Pluto. The objects are roughly two to three times as far from Pluto as Charon. The team plans to make follow-up Hubble observations in February to confirm the newly discovered objects are truly Pluto's moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2. The Hubble's Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. The candidates are roughly 5,000 times fainter than Pluto. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto. The team looked long and hard for other potential moons around Pluto. "These Hubble images represent the most sensitive search yet for objects around Pluto," said team member Andrew Steffl of the Southwest Research Institute. "It is unlikely that there are any other moons larger than about 10 miles across in the Pluto system," he said. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington. For detailed information and images about this research on the Web, visit: http://hubblesite.org/news/2005/19 For information about NASA and agency programs on the Web, visit: http://www.nasa.gov/home -------------------------------------------------------------------------------- Source: NASA |
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Nov 13 2005, 04:33 AM
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
In re to Comga's post:
(I'm speculating here) For thin Uranian style rings would effects of a nearby mass (such as Charon) be mostly in bumping up the eccentricity of each ring? If that was the extent of the effect, not sure we see a big hit in ring longevity in this possibility. (I assume between each narrow ring would lie a strong resonance from Charon) For broad Saturn style rings (with ring particles 'cheek by jowl') having the particles experiencing strong effects from Charon becomes, perhaps, more interesting. The dynamical ring spreading mechanism would seem to be enhanced in this scenario. Every orbit around the primary, all the ring particles bump more vigorously and transfer momentum across the ring plane. Would such effects 'overpower' the resonance 'curbs' in the ring system? Perhaps. Then we are in a scenario where, due to the strong momentum transfer across the ring system, we see a large effect 'pushing' the lower edge of the ring downward and the upper edge outward. This does not seem compatible with long ring retention, but, once the (possible) ring material thins out, you may approach the Uranian model, and perhaps get to see some skinny dark rings in 2014? Are there other 'damaging' effects of a nearby Charon on rings of Pluto other than increased orbital eccentricity? Inclination changes seems unlikely. Possible 'demethanization' of Charon from tidal heating would imply a slight degree of atmosphere interacting with the ring system when Charon passes between the sun and Pluto. Such an effect would not persist after tide lock, but atmosphereic drag and ring systems don't seem to go together. |
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Dec 1 2005, 03:36 PM
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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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