TNOs and Centaurs

Trans-Neptunian objects (TNOs) are icy bodies that orbit the Sun at and beyond the orbit of Neptune. Centaurs are bodies currently on chaotic orbits that cross those of the giant planets: they are thought to have originated farther out in the Solar System, and many will go on to become comets. These objects in the outer Solar System are thought to have originated from the primordial disk in which the Sun and planets formed. The region is particularly fascinating because it possibly contains a primordial population of objects, studies of which can lead to a better understanding of the formation and evolution of the Solar System. Knowledge concerning the formation of our Solar System can also lead to an enlightened concept of planetary formation processes of extrasolar planets as well as protoplanetary disks.

From 1998, we participated in the Deep Ecliptic Survey (DES) to discover Kuiper belt objects (KBOs) and Centaurs. The survey employed the wide-field Mosaic CCD cameras on 4-m telescopes at Kitt Peak National Observatory and Cerro Tololo International Observatory. Granted formal survey status from 2001-2005, the DES was designed to discover and determine the orbits of KBOs and Centaurs, with a goal of determining how dynamical phase space is filled in the outermost Solar System. The DES found over 600 new objects, with notable discoveries including Ixion, Chaos, the first Neptune Trojan, multiple Scattered objects, and multiple binary systems.

We have been involved with physical studies of TNOs, using the MIT-built Magellan Instant Camera (MagIC) on the 6.5-m Clay telescope at Las Campanas Observatory to determine light curves and colors. These studies provide insight into the composition of the objects and environmental conditions in the outer Solar System.

Stellar occultations are a powerful technique to study distant bodies in the Solar System, returning km-scale size and micro-bar level atmospheric measurements. We observed occultations by the Centaur Chiron in the 1990s, detecting surrounding material that was interpreted to be due to jets. In 2010, we reported the first successful stellar occultation by a TNO (55636). The discovery of rings around the Centaur Chariklo in 2013 launched a new topic of study: ring systems around minor planets. We continue to study TNOs and Centaurs using stellar occultations in order to determine fundamental physical characteristics, to look for atmospheres, rings, or other surrounding material, and to learn more about how small-body rings form and evolve.

For more information, please see our TNOs and Centaurs publications.