They delve into the nature of the enigmatic planetesimals

Trans-Neptunian objects (TNOs) are smaller bodies located beyond the orbit of Neptune, at the edge of the solar system. They are considered to be what remains of the largest of the building blocks from which the planets formed. Many of these large blocks, the planetesimals, grouped together with others to form planets, or fell into planets that were still in the process of formation.

As planetesimals that were never used in world formation, trans-Neptunian objects serve as pristine time capsules, preserving crucial evidence of the molecular processes and planetary migrations that shaped the solar system billions of years ago.

A new study of trans-Neptunian objects has revealed how their current colors and surface reflectance are linked to their formation sites in the early solar system. This line of research has also revealed the distribution of ice types in the early solar system and how trans-Neptunian objects evolve when they enter the region between the orbits of Jupiter and Saturn, becoming part of the category of celestial bodies. called centaurs.

The study is the work of a team made up of, among others, Noemí Pinilla-Alonso, from the University of Central Florida in the United States, and Rosario Brunetto, from the University of Paris-Saclay in France.

Before this study, trans-Neptunian objects were classified by class based only on their orbital properties and surface colors, but very little information was available on the precise chemical composition of these objects. Now, the results of the new study finally offer a clear way to obtain reliable information about the chemical composition of these stars from the coloration of their surfaces.

Using the James Webb Space Telescope (JWST), from NASA, ESA and CSA, respectively the US, European and Canadian space agencies, researchers measured the spectra of 54 trans-Neptunian objects, capturing detailed light patterns from these objects.

By analyzing these highly sensitive spectra, the study authors were able to identify specific chemicals on their surface.

Artistic recreation of a transneptunian object. (Illustration: NASA / ESA / G. Bacon / STScI)

Trans-Neptunian objects were classified into three distinct groups, based on their surface chemistry, also determined by the type of ice forming in each of three orbital regions when the solar system was forming. The temperature in each of these orbital bands, with different distances from the Sun, was adequate for the formation of one of several types of ice and its preservation.

One of the chemical groups encompasses 25% of the stars studied and is characterized by strong spectral absorptions in water ice lines and a dusty surface. In these planetesimals there are clear signs of crystalline water ice, but also low reflectance, indicating the presence of dark materials.

Another chemical group hosts 43% of the planetesimals investigated and shows strong bands of carbon dioxide (CO2) and some signs of complex organic substances.

The remaining chemical group encompasses 32% of the objects analyzed and exhibits strong signs of complex organic chemistry, methanol and nitrogen-containing substances. The surface of these planetesimals is the most reddish in color.

The study is titled “A DiSCo JWST portrait of the primordial Solar System through its trans-Neptunian objects.” And it has been published in the academic journal Nature Astronomy. (Fountain: NCYT by Amazings)