Recent research conducted by scientists from the University of Central Florida (UCF) using the James Webb Space Telescope (JWST) has unveiled unique characteristics of (2060) Chiron, a celestial object categorized as a 'centaur.' This object exhibits both cometary and asteroidal traits, providing valuable insights into the origins of our Solar System.
Chiron orbits the Sun between Jupiter and Neptune and is named after the mythological Centaur, reflecting its mixed characteristics. A study published in the journal Astronomy & Astrophysics revealed that Chiron's surface chemical composition differs from that of other centaurs.
For the first time, researchers identified carbon dioxide and carbon monoxide ice on its surface, along with carbon dioxide and methane gases in its coma, the cloud of dust and gas surrounding the object.
The research, led by Noemí Pinilla-Alonso and Charles Schambeau from the Florida Space Institute, builds on previous studies that detected carbon monoxide and carbon dioxide ice on trans-Neptunian objects (TNOs). These objects are believed to have remained unchanged since the formation of the Solar System.
Pinilla-Alonso stated, 'All small bodies in the Solar System provide clues about conditions in the past. However, active centaurs like Chiron offer more information. They undergo transformations due to solar heating, providing a unique opportunity to study the early materials of the universe.'
Discovered in 1977, Chiron exhibits unique properties compared to other centaurs. It sometimes behaves like a comet, possesses a surrounding ring of material, and may be enveloped by a debris field or rocky material.
Chiron originates from the TNO region and has traversed our Solar System since its inception. Its orbit occasionally brings it close to one of the giant planets, where gravitational interactions alter its trajectory, exposing it to various environments.
Pinilla-Alonso noted, 'What is unique about Chiron is that we can observe both the surface, where most ice can be found, and the coma, where we see gases originating from the surface or just beneath it.'
'TNOs do not exhibit such activity due to their extreme distance and cold temperatures. Asteroids also lack this activity as they contain no ice. Comets, on the other hand, show activity similar to centaurs but are usually observed closer to the Sun, with thick comas that obscure surface ice observations.'
The detection of ice and gas on an object as distant as Chiron—observed near its farthest point from the Sun—is significant, as it contextualizes other centaurs and sheds light on the early era of our Solar System.
Pinilla-Alonso emphasized that observations using the James Webb Space Telescope have for the first time revealed the abundance of Chiron's ice with varying volatility and formation processes.
Some of this ice, such as methane, carbon dioxide, and water ice, may be primordial components inherited from the pre-solar nebula. Others, like acetylene, propane, ethane, and carbon oxides, may have formed on the surface through reduction and oxidation processes.
'Chiron is a unique object,' Schambeau remarked. 'Its behavior raises many questions about the physical processes occurring within.'
Further research will be conducted to understand how seasonal variations and lighting patterns affect Chiron's behavior and ice reserves. As Chiron approaches, scientists hope to uncover more information about its surface composition.