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SUMMARY:The dynamics of rings around irregular bodies - Bruno Sicardy (Obs
 ervatoire de Paris)
DTSTART:20170621T150000Z
DTEND:20170621T160000Z
UID:TALK72247@talks.cam.ac.uk
CONTACT:Ed Gillen
DESCRIPTION:Stellar occultations revealed the surprising presence of dense
  rings\naround (10199) Chariklo (1\,2)\, a small Centaur object with diame
 ter ~250 km\nthat probably originates from the Trans-Neptunian region. Bef
 ore that discovery\,\nrings were known only around the four giant planets\
 , and it now appears that\nthose systems are more common in the universe t
 han previously thought.\nChariklo's rings exhibits resemblance with their 
 cousins of the giant planets\,\ne.g. the narrow and sharply confined Uranu
 s' rings. This calls for some active\nconfinement mechanisms\, e.g. by nea
 rly shepherd moonlets yet to be discovered.\nHowever\, there is a notewort
 hy difference with the giant planets:\nthe central body is small\, hence m
 uch more irregular than the gaseous planets\,\nwhich have esentially axisy
 mmetric gravitational potentials.\nHere\, we show that topographic feature
 s (e.g. mountains of a few km) or\na slight elongation of the body may ind
 uce strong corotation and Lindblad\nmean motion resonances on the rings.\n
 I will discuss the strength of such resonances and show that an initial\nd
 ebris disk surrounding Chariklo should be pushed away from the corotation\
 nradius\, so that the inner material falls onto the central body\, while t
 he\nouter material is pushed away at the present location of the rings.\nT
 he time scales associated are short enough - some 10^5 years - to explain 
 the\ncurrent structure of Chariklo's ring system: an empty region near the
  body\, with\nrings residing in the outermost part of Chariklo's Roche zon
 e.\n\n(1) F. Braga-Ribas et al.\, Nature 508\, 72 (2014)\n\n(2) B. Sicardy
  et al.\, arXiv 1612.03321 (2016)\n\nThis work receives funding from the E
 RC grant Agreement n°669416 "Lucky Star"
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
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