Kuiper Gürtel

SCATTERED KUIPER BELT OBJECTS (SKBOs)

• Origin
• How did the SKBOs get their eccentric, looping orbits? Fernandez (1980) suggested that planetesimals might be scattered into this type of orbit in the early days of the solar system. KBOs that approach Neptune closely are generally scattered away on short (million year) timescales. Many are passed to the dynamical control of other planets, ultimately to be lost from the solar system by ejection or by absorption (collision with a planet or the sun). Planetesimals ejected into very large orbits either escape from the gravitational influence of the sun (and then enter the realm of interstellar space) or may be perturbed by the galactic tidal field and by passing stars into orbits in the Oort Cloud. Objects scattered to the few 100 AU aphelion distances seen in the SKBOs are immune to galactic and stellar tides, and so remain in a tightly bound swarm (the fat doughnut) surrounding the solar system. Numerical simulations of this process by Duncan and Levison (1997) show this process in operation.

SCATTERED KUIPER BELT OBJECTS (SKBOs)

• Source of Short-Period Comets
• The dynamical involvement with Neptune means that the SKBOs are a potential source of short-period comets. Occasional Neptune perturbations can deflect SKBOs to planet-crossing orbits. Some of these bodies may find their way to the inner solar system, where sublimation of embedded ices will lead to their classification as comets. In part because the SKBO population is very uncertain, the ratio of short-period comets delivered from the resonances to those from the scattered disk is highly uncertain.

SEDNA

• Sedna was discovered as part of a continuing and highly productive survey lead by Mike Brown and Chad Trujillo, of Caltech and Gemini Observatory, respectively. The survey uses a wide-field telescope on Palomar Mountain to hunt for bright Kuiper Belt Objects (KBOs). The orbit has semimajor axis/eccentricity/inclination = a/e/i = 532AU/0.857/11.9.