By scrutinizing a duo of frigid asteroids lurking at the fringes of the Solar System, the James Webb Space Telescope is aiding researchers in deciphering the developmental journey of the icy giant Neptune. These insights might also illuminate how the primitive Earth became inundated with water, the crucial element that ultimately sparked the emergence of life.
The binary asteroid system Mors-Somnus has recently been identified as having formed within a chilly belt of celestial objects known as the Kuiper Belt. This zone lies beyond the orbit of Neptune, the eighth and most distant planet from the Sun. Thus, Mors-Somnus serves as a stand-in to investigate the vibrant history of Neptune and other icy entities in the Kuiper Belt, also referred to as trans-Neptunian objects (TNOs).
While some larger TNOs have previously been analyzed in detail, this study, part of the Discovering the Surface Composition of TNOs (DiSCo-TNOs) initiative, marks the first occasion where the surface composition of two segments of a small binary TNO pair has been examined. It is also the first time their chemical make-up has been uncovered.
"We are exploring how the genuine chemistry and physics of the TNOs reflect the arrangement of molecules based on carbon, oxygen, nitrogen, and hydrogen from the primordial cloud that formed the planets, their moons, and the smaller bodies," said Ana Carolina de Souza Feliciano, the lead researcher and DiSCo-TNOs program scientist at the Florida Space Institute. "These molecules were also fundamental to the origin of life and water on Earth." Binaries like Mors-Somnus are exceptional discoveries beyond the Kuiper Belt.
The gravitational interaction between such widely spaced binaries tends to be disrupted when they are not shielded by other icy masses and fragments within the belt. This suggests to the team that the mechanism by which Mors-Somnus was relocated to its current location beyond the Kuiper Belt must have been rather gradual.
De Souza Feliciano and her associates employed Webb to contrast the surface of Mors-Somnus with the surfaces of six other unperturbed TNOs, or 'cold classical' variants, confirming that they share numerous similarities. This led to the revelation that these cold, classical bodies, along with the asteroids Mors and Somnus, all originated approximately 2.7 billion miles away in the same Kuiper Belt sector. In this area, other TNOs are believed to have emerged as well.
Moreover, the observation that these bodies seem displaced from their initial places in the Kuiper Belt allows scientists to compare them with undisturbed cold classical TNOs and potentially trace how Neptune has moved to achieve its current orbit. These findings align perfectly with the expectations of researchers when the DiSCo-TNOs data from nearly 60 TNOs began arriving from Webb in late 2022.
"As we began to analyze the spectra of Mors and Somnus, more data was coming in, and the connection between the dynamic groups and compositional patterns felt intuitive," de Souza Feliciano remarked.
Research co-leader and Florida Space Institute investigator Noemí Pinilla-Alonso conceived the DiSCo-TNOs initiative. With its unparalleled spectral observation capabilities, she is confident that Webb will unveil even more information about objects in the Kuiper Belt and perhaps beyond Neptune in the future. "For the first time, we can not only resolve images of systems with multiple elements, but we can also examine their composition with a level of detail that only Webb can offer," Pinilla-Alonso stated.
"We can now investigate the formation processes of these binaries in ways previously unimaginable." Although Webb was intended to observe distant objects such as galaxies and quasars from the early universe – and thus billions of light-years from Earth – de Souza Feliciano contends that this research underscores Webb’s groundbreaking role. "Before Webb, no instrument could extract information from these objects at that wavelength range," she explained. "I am delighted to contribute to the epoch launched by Webb."
--Bhautik Thummar
