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Since 2013, dense and narrow rings are known around the small Centaur object Chariklo and the dwarf planet Haumea. Dense material has also been detected around the Centaur Chiron, although its nature is debated. This is the first time ever that rings are observed elsewhere than around the giant planets, suggesting that those features are more common than previously thought. The origins of those rings remain unclear. In particular, it is not known if the same generic process can explain the presence of material around Chariklo, Chiron, Haumea, or if each object has a very different history. Nonetheless, a specific aspect of small bodies is that they may possess a non-axisymmetric shape (topographic features and or elongation) that are essentially absent in giant planets. This creates strong resonances between the spin rate of the object and the mean motion of ring particles. In particular, Lindblad-type resonances tend to clear the region around the corotation (or synchronous) orbit, where the particles orbital period matches that of the body. Whatever the origin of the ring is, modest topographic features or elongations of Chariklo and Haumea explain why their rings should be found beyond the outermost 1/2 resonance, where the particles complete one revolution while the body completes two rotations. Comparison of the resonant locations relative to the Roche limit of the body shows that fast rotators are favored for being surrounded by rings. We discuss in more details the phase portraits of the 1/2 and 1/3 resonances, and the consequences of a ring presence on satellite formation.
The thermal emission of transneptunian objects (TNO) and Centaurs has been observed at mid- and far-infrared wavelengths - with the biggest contributions coming from the Spitzer and Herschel space observatories-, and the brightest ones also at sub-mi
Trans-Neptunian objects (TNOs) and Centaurs are remnants of our planetary system formation, and their physical properties have invaluable information for evolutionary theories. Stellar occultation is a ground-based method for studying these small bod
We present results of 6 years of observations, reduced and analyzed with the same tools in a systematic way. We report completely new data for 15 objects, for 5 objects we present a new analysis of previously published results plus additional data an
The sensitivity of ALMA makes it possible to detect thermal mm/submm emission from small/distant Solar System bodies at the sub-mJy level. Measured fluxes are primarily sensitive to the objects diameters, but deriving precise sizes is somewhat hamper
A second large programme (LP) for the physical studies of TNOs and Centaurs, started at ESO Cerro Paranal on October 2006 to obtain high-quality data, has recently been concluded. In this paper we present the spectra of these pristine bodies obtained