* Astronomy

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Kuiper Belt Object Occultations

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RE: Kuiper Belt

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Distant Minor Planets

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RE: Kuiper Belt

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The hunt continues for the outer solar system's tiniest residents. A two-year search to find small objects there has turned up nothing, bolstering theories that 'all hell broke loose' in the solar system just a few hundred million years after it formed.
Astronomers have found more than 1000 objects in the Kuiper Belt, a ring of icy bodies beyond Neptune. There are fewer large Kuiper Belt Objects than smaller ones, but the exact size distribution is unknown because only a handful of KBOs smaller than 70 kilometres across have been found they simply reflect too little sunlight to be observed.
The smallest KBOs seen so far measure about 30 km across and were found five years ago using the Hubble Space Telescope. But only a few were seen 25 times more of the small objects had been predicted based on the size distribution of larger KBOs.

Source

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Outer Solar System Not as Crowded as Astronomers Thought
When a treasure hunt comes up empty-handed, the hunters are understandably disappointed. But when astronomers don't find what they are looking for, the defeat can provide as much information as a successful search.
The search in question, the Taiwanese-American Occultation Survey (TAOS), spent two years periodically photographing portions of the sky to look for small chunks of rock and ice orbiting beyond Neptune, in a region of the solar system called the Kuiper Belt. The survey targeted Kuiper Belt objects (KBOs) with sizes between 2 miles (3 km) and 17 miles (28 km).
Since such objects are too small to see directly, the survey watched for stars to dim as KBOs passed in front of and occulted them. After accumulating more than 200 hours of data watching for stellar flickers lasting a second or less, TAOS did not spot any occultations.

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Title: The Kuiper Belt and Other Debris Disks
Authors: David Jewitt, Amaya Moro-Martín, Pedro Lacerda

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.

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Title: Colour-Inclination Relation of the Classical Kuiper Belt Objects
Authors: Nuno Peixinho, Pedro Lacerda, David Jewitt

We re-examine the correlation between the colours and the inclinations of the Classical Kuiper Belt Objects (CKBOs) with an enlarged sample of optical measurements. The correlation is strong (rho=-0.7) and highly significant (>8 sigma) in the range 0-34 deg. Nonetheless, the optical colours are independent of inclination below ~12 deg, showing no evidence for a break at the reported boundary between the so-called dynamically "hot" and "cold" populations near ~5 deg. The commonly accepted parity between the dynamically cold CKBOs and the red CKBOs is observationally unsubstantiated, since the group of red CKBOs extends to higher inclinations. Our data suggest, however, the existence of a different colour break. We find that the functional form of the colour-inclination relation is most satisfactorily described by a non-linear and stepwise behaviour with a colour break at ~12 deg. Objects with inclinations >12 deg show bluish colours which are either weakly correlated with inclination or are simply homogeneously blue, whereas objects with inclinations <12 deg are homogeneously red.

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Title: The Warped Plane of the Classical Kuiper Belt
Authors: Eugene Chiang, Hyomin Choi
(Version v2)

By numerically integrating the orbits of the giant planets and of test particles over a period of four billion years, we follow the evolution of the location of the midplane of the Kuiper belt. The Classical Kuiper belt conforms to a warped sheet that precesses with a 1.9 Myr period. The present-day location of the Kuiper belt plane can be computed using linear secular perturbation theory: the local normal to the plane is given by the theory's forced inclination vector, which is specific to every semimajor axis. The Kuiper belt plane does not coincide with the invariable plane, but deviates from it by up to a few degrees in stable zones. For example, at a semimajor axis of 38 AU, the local Kuiper belt plane has an inclination of 1.9 deg and a longitude of ascending node of 149.9 deg when referred to the mean ecliptic and equinox of J2000. At a semimajor axis of 43 AU, the local plane has an inclination of 1.9 deg and a nodal longitude of 78.3 deg. Only at infinite semimajor axis does the Kuiper belt plane merge with the invariable plane, whose inclination is 1.6 deg and nodal longitude is 107.7 deg. A Kuiper belt object keeps its inclination relative to the Kuiper belt plane nearly constant, even while the latter plane departs from the trajectory predicted by linear theory. The constancy of relative inclination reflects the undamped amplitude of free oscillation. Current observations of Classical Kuiper belt objects are consistent with the plane being warped by the giant planets alone, but the sample size will need to increase by a few times before confirmation exceeds 3-sigma in confidence. In principle, differences between the theoretically expected plane and the observed plane could be used to infer as yet unseen masses orbiting the Sun, but carrying out such a program would be challenging.

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Title: The Warped Plane of the Classical Kuiper Belt
Authors: Eugene Chiang, Hyomin Choi

By numerically integrating the orbits of the giant planets and of test particles for four billion years, we follow the evolution of the location of the midplane of the Kuiper belt. The Classical Kuiper belt conforms to a warped sheet that precesses with a 1.9 Myr period. The present-day location of the Kuiper belt plane can be computed using linear secular perturbation theory: the local normal to the plane is given by the theory's forced inclination vector, which is specific to every semi-major axis. The Kuiper belt plane does not coincide with the invariable plane, but deviates from it by up to a few degrees in stable zones. A Kuiper belt object keeps its free inclination relative to the Kuiper belt plane nearly constant, even while the plane departs from the trajectory predicted by linear theory. The constancy of free inclination simply reflects the undamped amplitude of free oscillation. Current observations of Classical Kuiper belt objects are consistent with the plane being warped by the giant planets alone, but the sample size will need to increase by a few times before confirmation exceeds 3-sigma in confidence. In principle, differences between the theoretically expected plane and the observed plane could be used to infer as yet unseen masses orbiting the Sun, but carrying out such a program would be challenging.

Read more (378kb, PDF)